Showing posts with label Evolution. Show all posts
Showing posts with label Evolution. Show all posts

Sunday, December 18, 2016

New analysis sheds light on Zika virus evolution, spread

In a study published in Pathogens and Global Health, researchers have modelled the evolutionary development and diversity of the Zika virus to better understand how infection spreads between populations and how the virus reacts with the immune system. Such an understanding is essential if an effective vaccine is to be developed.

First found in Uganda in 1947, Zika is the newest discovery among a group of mosquito-transmitted viruses known as flaviviruses. It is an emerging threat in South and Central America and the Caribbean, with the recent Brazilian epidemic resulting in 440,000-1,300,000 cases and spreading to more than thirteen other countries.

While infected people usually show no symptoms, these can include fever, rash, joint pain or conjunctivitis. In addition, the Brazilian outbreak indicated Zika might cause fetal losses in pregnant women or microcephaly in infants born to infected women.

Dr. Silvia Angeletti from the University Campus Bio-Medico, Rome, and colleagues, carried out evolutionary analysis of the virus combined with homology (shared ancestry) modelling and T- and B-cells epitope prediction, which aims to determine how immune system responses cause the virus to react and change.

Their analysis revealed two distinct genotypes of the virus, African and Asiatic, and two separate clades (biological groupings that include a common ancestor and all the descendants of that ancestor). Clade I represented African gene sequences and Clade II, sequences of Asiatic and Brazilian origin.

The Brazilian sequences were found to be closely related to a sequence from French Polynesia. This lends support to the hypothesis that the virus might have been introduced to Brazil during the Va'a World Sprint Canoeing Championship in Rio de Janeiro in 2014, which included a team from French Polynesia, rather than the World Cup in which no teams from Pacific countries participated.

Among the factors that influence Zika infection, 'antigenic variability' (the way the virus alters its surface proteins to evade the host's immune response) and pre-existing immunity caused by cross-reactions with other viruses might play an important role. Such cross-reactions also make diagnosis of Zika infection unreliable, and could thus facilitate the spread of the virus.

"Understanding the differences and similarities between Zika and other flaviviruses, such as the dengue fever and chikungunya viruses, is essential if effective drugs, vaccines and Zika-specific immunological tests for large population screening are to be designed," the authors say.
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Reference:

Science Daily. 2016. “New analysis sheds light on Zika virus evolution, spread”. Science Daily. Posted: October 12, 2016. Available online: https://www.sciencedaily.com/releases/2016/10/161012121025.htm

Thursday, December 15, 2016

Research to answer a 'crushing' evolutionary question

Studying the physical features of long-extinct creatures continues to yield surprising new knowledge of how evolution fosters traits desirable for survival in diverse environments. Placodonts are a case in point—specifically, the placodont teeth that Stephanie Crofts, an NJIT post-doctoral researcher, has written about in an article recently published in the journal Paleobiology. Now working with Assistant Professor of Biological Sciences Brooke Flammang in her Central King Building lab, Crofts is the co-author of "Tooth occlusal morphology in the durophagous marine reptiles, Placodontia (Reptilia: Sauropterygia)."

Placodonts, a group of extinct marine reptiles, lived at the beginning of the Triassic Period, the beginning of the age of dinosaurs, some 250 million years ago. They thrived in the shallows of the sea that split the ancient supercontinent Pangea. Their fossils have been found in Germany, Switzerland and Italy, and new specimens are being discovered in China.

All placodonts have teeth on their upper and lower jaws, as well as a set of teeth lining the roof of the mouth. But over their evolutionary history, Crofts explains, placodonts developed specialized "crushing" teeth well-suited for eating the "hard prey" creatures that shared their environment—creatures with thick shells, like clams or mussels.

The evolutionary ancestors of placodonts had long, pointy teeth, even on the roof of the mouth, especially suitable for catching soft-bodied prey. In contrast, placodonts are easily identified by their crushing teeth, bulbous in early placodonts and flattened in species that occur later in the evolutionary lineage. The basic question for Crofts: How well did these teeth function, and did later placodonts achieve an "optimal" crushing tooth?

International Investigation

Working with and international team of colleagues she met before joining NJIT in 2016, Crofts, traveled to museums throughout Europe to collect data on the shape of placodont teeth. Crofts' collaborators were James Neenan, a research fellow at the Oxford Museum of Natural History in England, Torsten Scheyer, associate professor at the University of Zurich's Palaeontological Institute and Museum, and Adam Summers, professor in the University of Washington's Department of Biology and head of the comparative vertebrate biomechanics lab at the university's marine field station, Friday Harbor Laboratories. Their investigative effort was made possible by funding from the Society of Vertebrate Paleontology, the University of Washington, the National Science Foundation and Swiss National Science Foundation.

In the course of her travel, Crofts compared the shapes of placodont teeth in the museum collections to models that tested how efficiently the teeth would break shells and how well they resisted breaking under pressure. Based on these models, Crofts and her team were able to predict that placodonts should have evolved a slightly rounded tooth surface, which would break shells efficiently without damaging the tooth itself. While some later occurring placodonts did just that, evolution equipped the latest known occurrences of these creatures with teeth that had quite different and very intriguing characteristics.

Instead of the predicted optimal tooth, this group of placodonts developed a complex tooth surface with a shallow, crescent-shaped furrow surrounding a small cusp on the principal crushing teeth. As Crofts and her collaborators suggest in the Paleobiology article, this tooth structure may have worked in a way similar to the function proposed for early hominin molars—with the furrow holding prey in place while the small cusp applies the force needed to break through the prey's shell. Further, Neenan and Scheyer have demonstrated that there is a slower rate of tooth replacement in this same group of placodonts, likely because changes in tooth shape protect the tooth from failure.

Palaeontological Perspectives

Crofts, who completed her Ph.D. at the University of Washington in 2016, brings a paleontological perspective and interest in the evolution of functional morphology to the increasing range of research under way in Flammang's Fluid Locomotion Laboratory. Flammang is the founding director of the lab, and with the assistance of Crofts and other colleagues is taking a multidisciplinary look at nature's marine propulsion systems. Crofts became interested in the postdoc position available at NJIT when she met Flammang while both were taking a course at Brown University on X-Ray Reconstruction of Moving Morphology (XROMM), an advanced technique for producing highly detailed 3D video of skeletal movement.

Crofts' current work at NJIT integrates comparative anatomy and physiology, biomechanics, hydrodynamics, and the use of biologically inspired robotic devices to investigate how aquatic organisms interact with their environment and drive the evolution of morphology and function. In addition to increasing the fund of basic scientific knowledge, it's work that has implications for the design of various types of submersible vehicles, including fully autonomous vehicles.

Reflecting on her research involving placodonts, Crofts says that it is a "window into the complexities and possibilities" inherent to the process of evolution. The placodonts she studied and wrote about surprised with teeth differing very significantly from those which evolved in other related species. At NJIT, Crofts is continuing the search for new insights into how evolution shapes the functional relationship of all creatures—including humans—with the surrounding world.
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Reference:

Phys.org. 2016. “Research to answer a 'crushing' evolutionary question”. Phys.org. Posted: October 5, 2016. Available online: http://phys.org/news/2016-10-evolutionary.html

Friday, July 8, 2016

Influence of religion and predestination on evolution and scientific thinking

Generally seen as antithetical to one another, evolution and religion can hardly fit in a scientific discourse simultaneously. However, biologist Dr Aldemaro Romero Jr.,Baruch College, USA, devotes his latest research article, now published in the open access Research Ideas and Outcomes (RIO), to observing the influences a few major religions have had on evolutionists and their scientific thinking over the centuries.

Inspired by the lack of pigmentation and/or eyes in some cave organisms, he focuses on biospeleology to challenge the notions of predetermination and linearity. Although the author makes it clear that fellow scientists do not claim their findings based on religion, he notes that "words matter and that words can hide a lot of the philosophical baggage that sooner or later may influence their ultimate conclusion".

Using examples from across the centuries, Dr Aldemaro Romero Jr. goes back to the times long before Charles Darwin had started compiling his prominent "The Origin of Species" and then turns once again to his evolutionist successors. Thus, he explores the link between the notion of predestination, underlying in various religions and nations, and the evolutionary theories.

The author notices that despite conclusions that evolution is not a linear process, biologists have never stopped seeing and contemplating "preadaptations" and "regressive evolution", when speculating on phenomena such as the lack of eyes in some exclusively cave-dwelling animals. Such choice of words can be easily traced back to assumptions of linearity and, therefore, predestination, common for various religions.

"Since the advent of Modern Synthesis we have a pretty consistent set of evidence that evolution is not linear, that there is not such a thing as direction for evolutionary processes, and that nothing is predetermined since natural selection, the main evolutionary mechanism, is a process that is not moved by any mystical force, nor directs beings toward a particular end," points out Dr Aldemaro Romero Jr..

"Therefore, I hope this paper serves as a warning to scientists that no matter what reductionist view they have in the way they practice their research, if they do not understand the historical roots and the philosophical framework of their research, they are doomed at presenting only a very partial (and many times biased) view of nature," he concludes.
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Reference:

EurekAlert. 2016. “Influence of religion and predestination on evolution and scientific thinking”. EurekAlert. Posted: April 28, 2016. Available online: http://www.eurekalert.org/pub_releases/2016-04/pp-ior042816.php

Sunday, June 12, 2016

Reconstructing the evolution of vegetation on Gran Canaria

Thanks to the analysis of fossil pollen and charcoal remains, a team of scientists has been able to reconstruct the evolution of the vegetation from Gran Canaria between 4,500 and 1,500 years ago. The study reveals that the disappearance of forests in some parts of the island is in part due to the rise in fires and the cultivation of cereals. Both factors are closely related to the arrival of the first indigenous people to the island.

In recent years, fossil pollen remains found on the Canary Islands of Tenerife and La Gomera have helped researchers to learn about changes in the composition of these islands’ forests during the Holocene (starting around 9,600 years ago approximately), as well as how humans have influenced these variations.

Analysing fossil pollen

A team of scientists led by the University of La Laguna has now carried out the first study on the vegetation of Gran Canaria by analysing fossil pollen. This analysis has allowed them to study the dynamics of the vegetation before and after human colonisation of the island. The results of their study have been published in the journal The Holocene.

“We have brought to light the importance of thermophilous vegetation (in this case junipers and palms), in the northern part of the island for at least the last 4,500 years, where it was thought that the dominant vegetation prior to the arrival of humans was mainly laurel forests,” explains Lea de Nascimento, a researcher at the University of La Laguna (Tenerife) and the main author of the study.

This study was carried out at Laguna de Valleseco, located in the northern part of the island, where fossil pollen and charcoal remains were extracted, making it possible to determine the natural features of the area during a period of time from approximately 2550 B.C. to 450 A.D.

The decline of the forests

According to the study, about 4,500 years ago the most abundant plant growth in this area of northern Gran Canaria was thermophilous vegetation, whose forests prefer warm temperatures. Among the species, trees of the genus Juniperus and the Canary Island date palm (Phoenix canariensis) are notable.

Nevertheless, trees began to disappear about 2,300 years ago from the area that was studied, a period of time which coincides with a rise in the frequency of fires caused by volcanic eruptions or by human presence on the island. “Volcanism during that period of time was very low in intensity and probably did not affect the forests being studied,” stresses the researcher. Therefore, “[the fires] were most likely caused by humans,” she states.

Furthermore, according to the scientist, the data indicate that the earliest inhabitants of Gran Canaria would have arrived on the island a few centuries before the earliest date of human presence known on the island according to archaeological records (1,900 years ago).

From this time onwards, the presence of shrubs and herbaceous plants progressively increases, while other types of vegetation, such as pine and laurel forests, continue to maintain a relatively low presence. Another of the most significant pieces of data provided by the study is the increase in cereal cultivation -especially from the 2nd century A.D. onwards- a reflection of how this agricultural activity gradually developed on the island.

The cultivation of cereals remained stable from then on, while no recovery of trees -especially fire trees (Morella faya)- is observed until the final time period studied, i.e. between the 4th and 5th centuries.

Consequences of human actions

In addition to the pollen remains, fragments of charcoal have been found in the Laguna de Valleseco, a remnant of the fires that took place then. The researchers believe that the inhabitants of the island burned large areas of land in order to obtain new farmland.

De Nascimento points out that the situation in Tenerife was similar to that of Gran Canaria. The arrival of the indigenous people affected the vegetation on the island and led to the decrease or disappearance of some trees, as well as the expansion of shrubs and herbaceous plants. More fires also broke out and an increase in grasses was detected.

Nevertheless, the study of La Gomera did not reveal any significant change in the composition of the forest following the arrival of humans, which could be explained by the fact that it is a small island that was colonised more recently, about 1,800 years ago, and thus had a smaller population.

“The only way to approximate the original state of the vegetation in the area studied would be to plant the plant species that existed there before the arrival of humans, and to eliminate those that are currently present as a result of human activity,” says de Nascimento.

At present, the scientists continue to work in Gran Canaria and Tenerife and are also analysing samples from Lanzarote and Fuerteventura. Outside of Spain, their new research focuses on other islands of Madeira and Cape Verde..

“Our main goal is to reconstruct the dynamics of the vegetation on the islands of Macaronesia over time and to link possible changes in the vegetation with climate change and human impact. Furthermore, we strive to integrate the palaeoecological information into the conservation and management of the nature of the islands,” concludes de Nascimento.
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Reference:

Past Horizons. 2016. “Reconstructing the evolution of vegetation on Gran Canaria”. Past Horizons. Posted: May 5, 2016. Available online: http://www.pasthorizonspr.com/index.php/archives/05/2016/reconstructing-the-evolution-of-vegetation-on-gran-canaria

Thursday, June 9, 2016

Influence of religion and predestination on evolution and scientific thinking

Generally seen as antithetical to one another, evolution and religion can hardly fit in a scientific discourse simultaneously. However, biologist Dr Aldemaro Romero Jr.,Baruch College, USA, devotes his latest research article, now published in the open access Research Ideas and Outcomes (RIO), to observing the influences a few major religions have had on evolutionists and their scientific thinking over the centuries.

Inspired by the lack of pigmentation and/or eyes in some cave organisms, he focuses on biospeleology to challenge the notions of predetermination and linearity. Although the author makes it clear that fellow scientists do not claim their findings based on religion, he notes that "words matter and that words can hide a lot of the philosophical baggage that sooner or later may influence their ultimate conclusion".

Using examples from across the centuries, Dr Aldemaro Romero Jr. goes back to the times long before Charles Darwin had started compiling his prominent "The Origin of Species" and then turns once again to his evolutionist successors. Thus, he explores the link between the notion of predestination, underlying in various religions and nations, and the evolutionary theories.

The author notices that despite conclusions that evolution is not a linear process, biologists have never stopped seeing and contemplating "preadaptations" and "regressive evolution", when speculating on phenomena such as the lack of eyes in some exclusively cave-dwelling animals. Such choice of words can be easily traced back to assumptions of linearity and, therefore, predestination, common for various religions.

"Since the advent of Modern Synthesis we have a pretty consistent set of evidence that evolution is not linear, that there is not such a thing as direction for evolutionary processes, and that nothing is predetermined since natural selection, the main evolutionary mechanism, is a process that is not moved by any mystical force, nor directs beings toward a particular end," points out Dr Aldemaro Romero Jr..

"Therefore, I hope this paper serves as a warning to scientists that no matter what reductionist view they have in the way they practice their research, if they do not understand the historical roots and the philosophical framework of their research, they are doomed at presenting only a very partial (and many times biased) view of nature," he concludes.
_________________
Reference:

EurekAlert. 2016. “Influence of religion and predestination on evolution and scientific thinking”. EurekAlert. Posted: April 28, 2016. Available online: http://www.eurekalert.org/pub_releases/2016-04/pp-ior042816.php

Monday, May 9, 2016

Population size fails to explain evolution of complex culture

There is a growing consensus among archaeologists and anthropologists that the size of a population determines its ability to develop as well as to maintain complex culture. This view is however severely compromised by a paper published this week in the Proceedings of the National Academy of Sciences (PNAS) by a research team including technology philosopher Krist Vaesen of the Eindhoven University of Technology.

Archeologists observe a fairly sudden appearance of behavioural modernity, such as complex technologies, abstract and realistic art and musical instruments, some 40,000 years ago, in the Later Stone Age. For decades archeologists and antropologists are looking for an explanation for these and other 'cultural revolutions', and in this way finding the origin of human culture. Since ten years or so the predominant theory says the driving factor would be growing population numbers.

Severely compromised

The logic seems inescapable indeed. The bigger the population, the higher the probability it contains an Einstein. Hence, bigger populations are more likely to develop complex culture. But this consensus view is however severely compromised by a paper published this week in the Proceedings of the National Academy of Sciences (PNAS) by a research team including technology philosopher Krist Vaesen from Eindhoven University of Technology (working in the Philosopy & Ethics group of the faculty Industrial Engineering and Innovation Sciences), along with archeologists from Simon Fraser University, La Trobe University and Leiden University. They refute this demography hypothesis with a growing body of ethnographic evidence.

Critical flaws

The authors reveal critical flaws both in the theoretical models and the empirical evidence behind such demographic interpretations of cultural innovation. The models support a relationship between population size and cultural complexity only for a restricted set of extremely implausible conditions. A critical analysis of the available archaeological evidence suggests that there are simply no data to infer that behavioural modernity emerged in a period of population growth or that the size of a population directly influences the rate of innovation in a society's technological repertoire.

Back to the drawing board

Hence, archaeologists may need to go back to the drawing board. the idea behind the demography hypothesis is attractive in its simplicity. But complex questions by definition demand complex answers. For the evolution of complex culture, no satisfying answer is available yet. The question of the emergence of complex culture remains as elusive as ever.
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Reference:

Phys.org. 2016. “Population size fails to explain evolution of complex culture”. Phys.org. Posted: April 5, 2016. Available online: http://phys.org/news/2016-04-population-size-evolution-complex-culture.html

Wednesday, June 24, 2015

From sticks to stones—getting a grip on the human genus

2015 has already been an amazing year for human evolution science.

We've witnessed an uncanny convergence of discoveries on the beginnings of the human genus,Homo, and all that it implies for understanding the evolution of a range of human characteristics, including culture and tool making.

Yet, the implications of this research run much deeper than most people would immediately think. Let me explain.

50 years of dogma

This year's major discoveries touch on a number of major historical themes in human origins research, spanning decades of investigation. The implications are broad, involving one of the key theoretical pillars of human origins that explains, among other things:

  • The arrival of fully committed terrestrial locomotion (or obligate bipedalism),
  • Enlargement and reorganization of the brain,
  • Speech and language,
  • Beginnings of human like culture and complex tool manufacturing,
  • A hunting and gathering lifestyle,
  • Endurance running linked perhaps to the "persistence hunt",
  • Regular consumption of meat, and
  • Use of fire and cooking.

Many elements of this 'package' of anatomical and behavioural traits probably began with the emergence of Homo around 2.3 million years ago. Actually, the discovery of a new Homo jaw from Ethiopia dated 2.8 million years old, which I wrote about in March, pushes this back a further half million years.

If we're honest, I guess, we should have expected the deconstruction of this central pillar of human evolution theory any time now, as there have been hints it was coming for quite a while.

2015 just happens to be the year when momentum has reached a point, through serendipitous discoveries, where its time to reassess the old model and forge ahead with a new one.

Homo the "handy-man"?

Ever since 1964, when Louis Leakey, Phillip Tobias and John Napier announced Homo habilis, and in so doing, redefined Homo, our genus has been linked to culture and tool making.

The nomen habilis was suggested by Raymond Dart, as it means "able, handy, mentally skillful or vigorous" in Latin.

Stone tool making, indicating the beginnings of culture, a fine 'precision grip' of the hand, and the start of a long-term trend in brain enlargement, were all linked to Homo and its then newest earliest member, Homo habilis.

Before this time, membership of the human genus was based mostly on the idea of a "cerebral Rubicon" in which a species had to have an estimated brain size of 700 cubic centimetres or more to belong.

Some features have been added to the package since 1964, such as the use of fire and cooking, and endurance running.

Deconstructing the Homo package

Ever since tool making was linked exclusively to Homo there have been dissenters.

At Olduvai Gorge in Tanzania, the Leakey's themselves found tools, dubbed the "Oldowan" Industry, associated with the "Nutcracker Man" or Paranthropus bosiei as well as Homo habilis.

In the 1960s, one of Leakey's own protégés, Jane Goodall, showed that chimpanzees also used tools in the wild.

Only last week, Jill Pruetz at Iowa State University and her team reported that chimpanzees in Senegal used wooden spears for hunting, being the only example of a living non-human species to do so.

Over the last couple of decades we've also learnt that very different kinds of animals use tools, from ants to octopuses, crows to otters, and dolphins to monkeys and apes.

In South Africa, stone tools have also been recovered from various ancient cave sites along side 2 million year old Homo and Paranthropus fossils.

Studies of the hand bones of Paranthropus by Randy Susman in the 1980s showed their anatomy was similar to humans: although, we have no idea if they had the motivation, need or smarts to make tools.

In 2010, cut-marks on large mammal bones made by early hominins using stone tools were reported from Ethiopia, dating to 3.39 million years ago, by Shannon McPherron and her team.

This pushed tool use well beyondHomo and Paranthropus to Kenyanthropus or even Australopithecus.

Last week, Sonia Harmand and her team at Stony Brook University announced at a conference in California that they'd found stone tools on the shores of Lake Turkana in Kenya dating to around 3.3 million years old.

This discovery pushes the oldest tools back a whopping 800,000 years!

This new tool industry differs from the Oldowan in being much chunkier, including tools weighing as much as 15 kilograms: according to a report in this week's Nature by Ewen Calloway (the work has yet to be published in a scientific journal).

And, just this week, a new study published by Thomas Feix from Yale University and co-investigators proposed that the East African species Australopithecus afarensis living between roughly 3 and 4 million years ago may also have had a human-like hand grip.

This follows on from research reported in January by Matthew Skinner from the University of Kent and his team showing that the southern African species, Australopithecus africanus, may also have routinely made and used tools.

All of these discoveries call into question the whole Homo package: if tools were made by hominins like Australopithecus, then they can't be associated with obligate bipedalism, brain enlargement, speech and language or the use of fire.

These are features we associate only with members of Homo.

A cultured ape?

Over the last few decades, the surprising finding of tool use by arthropods, molluscs and many species of chordate (including birds and mammals), has thrown a massive spanner in the works for scientists wrestling with the notion of "culture." In one camp – normally biologists – the definition of culture has been expanded to include most or all instances of non-human tool use.

In the other – comprising mostly archaeologists – it has been narrowed to include only behaviours seen in Homo sapiens and some of our early ancestors.

But, are there any unique features in the way humans, and our extinct biped relatives, made and used stone tools?

We humans stand out in making an extraordinary diversity of tools, including ones that are highly complex, comprising many components that interact in complicated ways, with some tools based in experimental research or deep insights about nature. Just think about your car or smart phone as an example of high-tech tool.

Archaeologists have had a hard time wrestling with the problem of the uniqueness of human culture, especially in the face of the complexity of ape cultures, but as well as the use of tools across very diverse kinds of animals.

For example, passerine birds and most primates are known to use similar numbers of tools and in similarly complex situations. Yet, humans do things differently.

The archaeologists Iain Davison, from the University of New England, and William McCrew, Cambridge University, believe they have pinned down from a behavioural perspective what humans do that is so distinctintive.

They believe we are far more creative, generating new kinds of behaviours from those learned from other people, and that human stone tool making has provided a "niche" for the coopting of tools and tool-making procedures across different contexts.

Such ideas prove extremely difficult to test from archaeology alone though.

Uniqueness reassessed

We now seem to be at the point in scientific history where the package of features normally associated with the beginnings of Homo no longer seems valid, after 50 years of their use.

Many of the hallmarks of the human genus have been convincingly found with other, much more ancient hominin species, and some even with other kinds of animals.

At the same time, finding the evolutionary origins of the very real 'gulf' that exists between us and other life – one that is admittedly getting smaller each year – seems to be an increasingly difficult challenge for science.
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Reference:

Curnoe, Darren. 2015. “From sticks to stones—getting a grip on the human genus”. Phys.org. Posted: April 24, 2015. Available online: http://phys.org/news/2015-04-stonesgetting-human-genus.html

Monday, April 20, 2015

Ancient fossils reveal diversity in the body structure of human ancestors

Recently released research on human evolution has revealed that species of early human ancestors had significant differences in facial features. Now, a University of Missouri researcher and her international team of colleagues have found that these early human species also differed throughout other parts of their skeletons and had distinct body forms. The research team found 1.9 million-year-old pelvis and femur fossils of an early human ancestor in Kenya, revealing greater diversity in the human family tree than scientists previously thought.

"What these new fossils are telling us is that the early species of our genus, Homo, were more distinctive than we thought. They differed not only in their faces and jaws, but in the rest of their bodies too," said Carol Ward, a professor of pathology and anatomical sciences in the MU School of Medicine. "The old depiction of linear evolution from ape to human with single steps in between is proving to be inaccurate. We are finding that evolution seemed to be experimenting with different human physical traits in different species before ending up with Homo sapiens."

Three early species belonging to the genus Homo have been identified prior to modern humans, or Homo sapiens. Homo rudolfensis and Homo habilis were the earliest versions, followed by Homo erectus and then Homo sapiens. Because the oldest erectus fossils that have been found are only 1.8 million years old, and have different bone structure than the new fossil, Ward and her research team conclude that the fossils they have discovered are either rudolfensis or habilis. Ward says these fossils show a diversity in the physical structures of human ancestors that has not been seen before.

"This new specimen has a hip joint like all other Homo species, but it also has a thinner pelvis and thighbone compared to Homo erectus," Ward said. "This doesn't necessarily mean that these early human ancestors moved or lived differently, but it does suggest that they were a distinct species that could have been identified not just from looking at their faces and jaws, but by seeing their body shapes as well. Our new fossils, along with the other new specimens reported over the past few weeks, tell us that the evolution of our genus goes back much earlier than we thought, and that many species and types of early humans coexisted for about a million years before our ancestors became the only Homo species left."

A small piece of the fossil femur was first discovered in 1980 at the Koobi Fora site in Kenya. Project co-investigator Meave Leakey returned to the site with her team in 2009 and uncovered the rest of the same femur and matching pelvis, proving that both fossils belonged to the same individual 1.9 million years ago.
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Reference:

EurekAlert. 2015. “Ancient fossils reveal diversity in the body structure of human ancestors”. EurekAlert. Posted: March 9, 2015. Available online: http://www.eurekalert.org/pub_releases/2015-03/uom-afr030915.php

Monday, April 13, 2015

Mapping 'switches' that shaped the evolution of the human brain

Thousands of genetic "dimmer" switches, regions of DNA known as regulatory elements, were turned up high during human evolution in the developing cerebral cortex, according to new research from the Yale School of Medicine.

Unlike in rhesus monkeys and mice, these switches show increased activity in humans, where they may drive the expression of genes in the cerebral cortex, the region of the brain that is involved in conscious thought and language. This difference may explain why the structure and function of that part of the brain is so unique in humans compared to other mammals. The research, led by James P. Noonan, Steven K. Reilly, and Jun Yin, is published March 6 in the journal Science.

In addition to creating a rich and detailed catalogue of human-specific changes in gene regulation, Noonan and his colleagues pinpointed several biological processes potentially guided by these regulatory elements that are crucial to human brain development.

"Building a more complex cortex likely involves several things: making more cells, modifying the functions of cortical areas, and changing the connections neurons make with each other. And the regulatory changes we found in humans are associated with those processes," said Noonan, associate professor of genetics, an investigator with the Kavli Institute for Neuroscience, and senior author of the study. "This likely involves evolutionary modifications to cellular proliferation, cortical patterning, and other developmental processes that are generally well conserved across many species."

Scientists have become adept at comparing the genomes of different species to identify the DNA sequence changes that underlie those differences. But many human genes are very similar to those of other primates, which suggests that changes in the way genes are regulated -- in addition to changes in the genes themselves -- is what sets human biology apart.

Up to this point, however, it has been very challenging to measure those changes and figure out their impact, especially in the developing brain. The Yale researchers took advantage of new experimental and computational tools to identify active regulatory elements -- those DNA sequences that switch genes on or off at specific times and in specific cell types -- directly in the human cortex and to study their biological effects.

First, Noonan and his colleagues mapped active regulatory elements in the human genome during the first 12 weeks of cortical development by searching for specific biochemical, or "epigenetic" modifications. They did the same in the developing brains of rhesus monkeys and mice, then compared the three maps to identify those elements that showed greater activity in the developing human brain. They found several thousand regulatory elements that showed increased activity in human.

Next, they wanted to know the biological impact of those regulatory changes. The team turned to BrainSpan, a freely available digital atlas of gene expression in the brain throughout the human lifespan. (BrainSpan was led by Kavli Institute member Nenad Sestan at Yale, with contributions from Noonan and Pasko Rakic, a co-author on this study.) They used those data to identify groups of genes that showed coordinated expression in the cerebral cortex. They then overlaid the regulatory changes they had found with these groups of genes and identified several biological processes associated with a surprisingly high number of regulatory changes in humans.

"While we often think of the human brain as a highly innovative structure, it's been surprising that so many of these regulatory elements seem to play a role in ancient processes important for building the cortex in all mammals, said first author Steven Reilly. "However, this is often a hallmark of evolution, tinkering with the tools available to produce new features and functions." Next, Noonan and colleagues plan to investigate the function of some of the regulatory changes they identified by introducing them into the mouse genome and studying their effects on mouse brain development.

The research was funded by the National Institutes of Health (GM094780, DA023999, NS014841, GM106628) and a NSF Graduate Research Fellowship. It was conducted in collaboration with Pasko Rakic, director of the Kavli Institute at Yale and one of the world's leading experts on the development of the human cortex. Other authors were Deena Emera, Jing Leng, Justin Cotney and Richard Sarro in the Noonan lab and Albert E. Ayoub in the Rakic lab.
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Reference:

Science Daily. 2015. “Mapping 'switches' that shaped the evolution of the human brain”. Science Daily. Posted: March 5, 2015. Available online: http://www.sciencedaily.com/releases/2015/03/150305152105.htm

Saturday, January 4, 2014

Science on the trail of The Wolf and Little Red Riding Hood

Mathematical modelling provides insights into the origins and evolution of folk tales

New insights into the origins and development of folk tales such as Little Red Riding Hood are being provided by the application of scientific analysis more commonly used by biologists to produce an evolutionary tree of life diagram.

In the scientific journal, PLOS ONE, published today (13 November), Dr Jamie Tehrani, an anthropologist at Durham University, England, resolves a long-running debate by demonstrating that Little Red Riding Hood shares a common but ancient root with another popular international folk tale The Wolf and the Kids, although the two are now distinct stories.

"This is rather like a biologist showing that humans and other apes share a common ancestor but have evolved into distinct species," explained Dr Tehrani, who found that The Wolf and the Kids probably originated in the 1st century AD, with Little Red Riding Hood branching off 1,000 years later.

The Wolf and the Kids, popular in Europe and the Middle East, is a story about a wolf who impersonates a nanny goat and devours her kids, whereas Little Red Riding Hood is about a wolf who devours a young girl after impersonating her grandmother. Variants of the story are common in Africa and Asia, for example, The Tiger Grandmother in Japan, China and Korea.

Little Red Riding Hood was told by the Brothers Grimm 200 years ago but that version was based on an earlier, 17th century, story written by the Frenchman Charles Perrault, which itself derived from an older, oral tradition of storytelling in France, Austria and northern Italy.

Dr Tehrani subjected 58 variants of the folk tales with phylogenetic analysis, a method more commonly used by biologists for grouping together closely-related organisms to form a tree of life diagram, mapping out the various branches of evolution from the earliest life forms.

The analysis focused on 72 plot variables, such as the character of the protagonist (for example male or female, single child or group of siblings); the character of the villain (wolf, ogre, tiger or other creature), the tricks used by the villain to deceive the victim and whether the victim is eaten, escapes or is rescued.

Phylogenetics involves a mathematical modelling process that compares similarities between the plot variables and scores them according to the probability that they have the same origin. This enables a tree to be constructed showing the most likely paths, or branches, of the evolution of the story.

Dr Tehrani said: "My research cracks a long-standing mystery. The African tales turn out to be descended from The Wolf and the Kids but over time, they have evolved to become like Little Red Riding Hood, which is also likely to be descended from The Wolf and the Kids.

"This exemplifies a process biologists call convergent evolution, in which species independently evolve similar adaptations. The fact that Little Red Riding Hood 'evolved twice' from the same starting point suggests it holds a powerful appeal that attracts our imaginations.

"There is a popular theory that an archaic, ancestral version of Little Red Riding Hood originated in Chinese oral tradition. It is claimed the tale spread west, along the Silk Route, and gave rise to both The Wolf and the Kids and the modern version of Little Red Riding Hood. My analysis demonstrates that in fact the Chinese version is derived from European oral traditions, and not vice versa.

"Specifically, the Chinese blended together Little Red Riding Hood, The Wolf and the Kids and local folktales to create a new, hybrid story. Interestingly, this tale was first written down by the Chinese poet Huang Zhing, who was a contemporary of Perrault, who first wrote down the European version of Little Red Riding Hood in the 17th century.

"This implies that the Chinese version is not derived from literary versions of Little Red Riding Hood but from the older, oral version, with which it shares crucial similarities. It is therefore understandable that previous scholars have assumed it to be ancestral to the European tale – but actually it's the other way around."

Dr Tehrani, whose research is funded by Research Councils UK, is now applying phylogenetics to other folk tales and believes that his research could shed light on the migration patterns of humans in ancient times, by determining the origins and evolution of the folk stories being told at various locations and dates.
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References:

EurekAlert. 2014. “Science on the trail of The Wolf and Little Red Riding Hood”. EurekAlert. Posted: November 13, 2013. Available online: http://www.eurekalert.org/pub_releases/2013-11/du-sot111213.php

Monday, July 8, 2013

Cultural products have evolutionary roots

Concordia University professor shows humans are hard-wired to consume

From Brad Pitt fighting zombies to Superman falling for Lois Lane, summer blockbuster season is upon us. But while Hollywood keeps trotting out new movies for the masses, plotlines barely change.

Epic battles, whirlwind romances, family feuds, heroic attempts to save the lives of strangers: these are stories guaranteed to grace the silver screen. According to new research from Concordia University, that's not lazy scriptwriting, that's evolutionary consumerism.

Marketing professor Gad Saad says evolution has hard-wired humans to be naturally drawn toward a specific set of universal narratives within cultural products. His new article in the Journal of Consumer Psychology shows that little in consumer behaviour can be fully understood without the guiding light of evolution.

"The human drive to consume is rooted in a shared biological heritage based around four key Darwinian factors: survival, reproduction, kin selection and reciprocal altruism. These fundamental evolutionary forces shape the narratives that are created by film producers or song writers," explains Saad, who holds the Concordia University Research Chair in Evolutionary Behavioural Sciences and Darwinian Consumption, within the John Molson School of Business.

That's true for other pop culture products like song lyrics, which Saad says offer "one of the most direct windows to our evolved mating psychology." From Bieber to Beyoncé, it's all about signalling wealth and finding a mate.

Saad explains that the focus of 90% of songs is on universal sex-specific preferences in the attributes we desire in prospective mates. Male singers show off their wealth and engage in conspicuous consumption via high status brand mentions. On the other hand, female singers refer to their own "bootylicious" physical beauty and call for "no scrubs" in order to denigrate men of low social status.

"Romance novels, pop songs and movie plotlines always come back to the Darwinian themes of survival (injuries and deaths), reproduction (courtships, sexual assaults, reputational damage), kin selection (the treatment of one's progeny), and altruistic acts (heroic attempts to save a stranger's life). Movies, television shows, song lyrics, romance novels, collective wisdoms, and countless other cultural products are a direct window to our biologically based human nature," says Saad.

It's not just cultural products that demonstrate the evolutionary roots of what Saad terms "Homo consumericus." From the food we eat to the clothing we buy, we're always under the influence of evolution.

For Saad, the practical implications are clear: "In order to achieve commercial success, cultural products typically have to offer content that is congruent with our evolved human nature." That means that Clark Kent will fall for Lois Lane while Superman saves the planet for a long time to come.
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References:

EurekAlert. 2013. “Cultural products have evolutionary roots”. EurekAlert. Posted: June 12, 2013. Available online: http://www.eurekalert.org/pub_releases/2013-06/cu-cph061213.php

Thursday, June 13, 2013

Texas A&M study: Prehistoric ear bones could lead to evolutionary answers

The tiniest bones in the human body – the bones of the middle ear – could provide huge clues about our evolution and the development of modern-day humans, according to a study by a team of researchers that include a Texas A&M University anthropologist.

Darryl de Ruiter, a professor in the Department of Anthropology at Texas A&M, and colleagues from Binghamton University (the State University of New York) and researchers from Spain and Italy have published their work in the current issue of PNAS (Proceedings of the National Academy of Science).

The team examined the skull of a hominin believed to be about 1.9 million years old and found in a cave called Swartkrans, in South Africa. Of particular interest to the team were bones found in the middle ear, especially one called the malleus. It and the other ear bones – the incus and the stapes – together show a mixture of ape-like and human-like features, and represent the first time all three bones have been found together in one skull.

The malleus appears to be very human-like, the findings show, while the incus and stapes resemble those of a more chimpanzee-like, or ape-like creature. Since both modern humans and our early ancestors share this human-like malleus, the changes in this bone must have occurred very early in our evolutionary history.

"The discovery is important for two reasons," de Ruiter explains.

"First, ear ossicles are fully formed and adult-sized at birth, and they do not undergo any type of anatomical change in an individual lifetime. Thus, they are a very close representation of genetic expression. Second, these bones show that their hearing ability was different from that of humans – not necessarily better or worse, but certainly different.

"They are among the rarest of fossils that can be recovered," de Ruiter adds.

"Bipedalism (walking on two feet) and a reduction in the size of the canine teeth have long been held to be 'hallmarks of humanity' since they seem to be present in the earliest human fossils recovered to date. Our study suggests that the list may need to be updated to include changes in the malleus as well."

de Ruiter recently authored a series of papers in Science magazine that demonstrate the intermediate nature of the closely related species, Australopithecus sediba, and provide strong support that this species lies rather close to the ancestry of Homo sapiens. The current study could yield additional new clues to human development and answer key questions of the evolution of the human lineage.
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References:

EurekAlert. 2013. “Texas A&M study: Prehistoric ear bones could lead to evolutionary answers”. EurekAlert. Posted: May 13, 2013. Available online: http://www.eurekalert.org/pub_releases/2013-05/tau-tas051313.php

Sunday, March 3, 2013

Social evolution: The ritual animal

Praying, fighting, dancing, chanting — human rituals could illuminate the growth of community and the origins of civilization.

By July 2011, when Brian McQuinn made the 18-hour boat trip from Malta to the Libyan port of Misrata, the bloody uprising against Libyan dictator Muammar Gaddafi had already been under way for five months.

“The whole city was under siege, with Gaddafi forces on all sides,” recalls Canadian-born McQuinn. He was no stranger to such situations, having spent the previous decade working for peace-building organizations in countries including Rwanda and Bosnia. But this time, as a doctoral student in anthropology at the University of Oxford, UK, he was taking the risk for the sake of research. His plan was to make contact with rebel groups and travel with them as they fought, studying how they used ritual to create solidarity and loyalty amid constant violence.

It worked: McQuinn stayed with the rebels for seven months, compiling a strikingly close and personal case study of how rituals evolved through combat and eventual victory. And his work was just one part of a much bigger project: a £3.2-million (US$5-million) investigation into ritual, community and conflict, which is funded until 2016 by the UK Economic and Social Research Council (ESRC) and headed by McQuinn's supervisor, Oxford anthropologist Harvey Whitehouse.

Rituals are a human universal — “the glue that holds social groups together”, explains Whitehouse, who leads the team of anthropologists, psychologists, historians, economists and archaeologists from 12 universities in the United Kingdom, the United States and Canada. Rituals can vary enormously, from the recitation of prayers in church, to the sometimes violent and humiliating initiations of US college fraternity pledges, to the bleeding of a young man's penis with bamboo razors and pig incisors in purity rituals among the Ilahita Arapesh of New Guinea. But beneath that diversity, Whitehouse believes, rituals are always about building community — which arguably makes them central to understanding how civilization itself began.

To explore these possibilities, and to tease apart how this social glue works, Whitehouse's project will combine fieldwork such as McQuinn's with archaeological digs and laboratory studies around the world, from Vancouver, Canada, to the island archipelago of Vanuatu in the south Pacific Ocean. “This is the most wide-ranging scientific project on rituals attempted to date,” says Scott Atran, director of anthropological research at the CNRS, the French national research organization, in Paris, and an adviser to the project.

Human rites

A major aim of the investigation is to test Whitehouse's theory that rituals come in two broad types, which have different effects on group bonding. Routine actions such as prayers at church, mosque or synagogue, or the daily pledge of allegiance recited in many US elementary schools, are rituals operating in what Whitehouse calls the 'doctrinal mode'. He argues that these rituals, which are easily transmitted to children and strangers, are well suited to forging religions, tribes, cities and nations — broad-based communities that do not depend on face-to-face contact.

Rare, traumatic activities such as beating, scarring or self-mutilation, by contrast, are rituals operating in what Whitehouse calls the 'imagistic mode'. “Traumatic rituals create strong bonds among those who experience them together,” he says, which makes them especially suited to creating small, intensely committed groups such as cults, military platoons or terrorist cells. “With the imagistic mode, we never find groups of the same kind of scale, uniformity, centralization or hierarchical structure that typifies the doctrinal mode,” he says.

Rebel yell

Whitehouse has been developing this theory of 'divergent modes of ritual and religion' since the late 1980s, based on his field work in Papua New Guinea and elsewhere1. His ideas have attracted the attention of psychologists, archaeologists and historians.

Until recently, however, the theory was largely based on selected ethnographic and historical case studies, leaving it open to the charge of cherry-picking. The current rituals project is an effort by Whitehouse and his colleagues to answer that charge with deeper, more systematic data.

The pursuit of such data sent McQuinn to Libya. His strategy was to look at how the defining features of the imagistic and doctrinal modes — emotionally intense experiences shared among a small number of people, compared with routine, daily practices that large numbers of people engage in — fed into the evolution of rebel fighting groups from small bands to large brigades.

At first, says McQuinn, neighbourhood friends formed small groups comprising “the number of people you could fit in a car”. Later, fighters began living together in groups of 25–40 in disused buildings and the mansions of rich supporters. Finally, after Gaddafi's forces were pushed out of Misrata, much larger and hierarchically organized brigades emerged that patrolled long stretches of the defensive border of the city. There was even a Misratan Union of Revolutionaries, which by November 2011 had registered 236 rebel brigades.

McQuinn interviewed more than 300 fighters from 21 of these rebel groups, which varied in size from 12 to just over 1,000 members2. He found that the early, smaller brigades tended to form around pre-existing personal ties, and became more cohesive and the members more committed to each other as they collectively experienced the fear and excitement of fighting a civil war on the streets of Misrata.

But six of the groups evolved into super-brigades of more than 750 fighters, becoming “something more like a corporate entity with their own organizational rituals”, says McQuinn. A number of the group leaders had run successful businesses, and would bring everyone together each day for collective training, briefings and to reiterate their moral codes of conduct — the kinds of routine group activities characteristic of the doctrinal mode. “These daily practices moved people from being 'our little group' to 'everyone training here is part of our group',” says McQuinn.

McQuinn and Whitehouse's work with Libyan fighters underscores how small groups can be tightly fused by the shared trauma of war, just as imagistic rituals induce terror to achieve the same effect. Whitehouse says that he is finding the same thing in as-yet-unpublished studies of the scary, painful and humiliating 'hazing' rituals of fraternity and sorority houses on US campuses, as well as in surveys of Vietnam veterans showing how shared trauma shaped loyalty to their fellow soldiers.

To gain a more global perspective on ritual practices, Whitehouse and Quentin Atkinson, a psychologist at the University of Auckland, New Zealand, and a member of the project, used a previously developed database containing information on world cultures to explore the connections between frequency, peak levels of emotional arousal, and average community size for 645 rituals across 74 cultures3. As predicted, the rituals fell into two clusters: low-frequency but high-arousal imagistic varieties that were more common in societies with a smaller average community size, and high-frequency, low-arousal doctrinal rituals that were more established in societies in which communities are larger.

Given these data from contemporary cultures, it is hard not to speculate about ritual's role in history: did the transition from imagistic mode to doctrinal mode, with its emphasis on a common identity buttressed by daily activities and rituals, play a part in the emergence of large, complex societies 10,000 years ago?

The birth of civilization?

To address that question, Whitehouse, Atkinsonand Camilla Mazzucato, also based at the University of Oxford, are looking at archaeological data from Çatalhöyük, one of the largest and best-preserved Neolithic towns known. Located in the Anatolian plains of northwestern Turkey, Çatalhöyük was founded during the dawn of agriculture roughly 9,500 years ago, and housed more than 8,000 people at its peak.

The town's early layers show that residents frequently buried their kin under the floors of their houses, sometimes with their heads severed. Wall paintings also depict the town's residents getting together to tease and kill enormous wild bulls for feasting. “The whole process of baiting and killing these animals would have been extremely intense, and have had a major emotional impact,” says excavation director Ian Hodder, an archaeologist at Stanford University in California. These occasional feasts were also memorialized by mounting the skulls and horns of bulls inside houses, and burying the rest of the bones to commemorate the founding or abandonment of a house, which Hodder says were also highly ritualistic events.

Evidence for such imagistic-style rituals declines in the later layers of Çatalhöyük. Wild-bull rituals and bull-horn installations become less common as the herding of domesticated sheep, goats and cattle intensified, says Hodder. Human burials within houses fade out, and standardized symbolic artefacts, such as painted pottery and seal stamps, become more common. Whitehouse and Hodder believe that these changes represent a shift to a more doctrinal mode of ritual as people united into a larger, more cooperative community devoted to agriculture and animal herding. Although speculative, this interpretation is consistent with Whitehouse and Atkinson's cross-cultural survey, which found that in contemporary societies the doctrinal mode is more established where agriculture is practised most intensively.

Looking beyond Çatalhöyük, Whitehouse, Atkinson and Mazzucato are building a regional database chronicling similar changes in ritual at 60 other sites across the Middle East, from the end of the Palaeolithic around 10,000 years ago until the early Bronze Age around 7,000 years ago. This database will dovetail with another one that covers the entire world over the past 5,000 years4. That resource codifies information about the culture, religion and ritual practices of people worldwide, and combines this with measures of social complexity — for example, how many levels of administration a society's government has, or the number of distinct professions — as well as data on the intensity of warfare. The plan is to use this database to explore the links between ritual and social life, as well as the roles of war and competition between societies in nurturing certain kinds of ritual and driving increases in social complexity.

Members of the ESRC project are also probing people's beliefs about how rituals work. For example, Cristine Legare at the University of Texas at Austin has studied Brazilian rituals called simpatias, which are used to solve everyday problems ranging from bad luck to asthma and depression5. A simpatia for getting a good job says that during the full Moon the jobseeker must take the jobs page out of a newspaper, fold it four times, and then place it on the floor with a small white candle surrounded by honey and cinnamon, imagining themself in a new job with good pay. The candle stub and the paper should be buried with a plant and watered daily, and the dream job will soon emerge.

The ritual mind

Legare presented Brazilians with a variety of simpatias, and found that people judged them as more effective when they involved a large number of repetitive procedural steps that must be performed at a specific time and in the presence of religious icons. “We're built to learn from others,” she says, which leads us to repeat actions that seemed to work for someone else — “even if we don't understand how they produce the desired outcomes”.

Meanwhile, psychologist Ryan McKay at Royal Holloway, University of London, and Jonathan Lanman, a cognitive anthropologist at Queen's University, Belfast, are exploring how rituals can be broken down into their component parts and how each part influences behaviour. One such component is synchronized physical action — for example, the ritualized goose-stepping of military units — which social psychologists have shown6 promotes a sense of connection and trust between individuals.

This work builds on research by Richard Sosis, an anthropologist at the University of Connecticut, who has shown that immersion in collective rituals, such as communal prayer, in Israeli kibbutzim increases cooperative behaviour in economic games7 — but only with other kibbutz members8.

Ritual also has its darker side. Surveys by Ara Norenzyan, a psychologist at the University of British Columbia in Vancouver who has an advisory role on the project, suggest that support for suicide terrorism among Palestinians is more strongly tied to communal ritual attendance than to religious devotion, as measured by the frequency of private prayer9.

Atran thinks that rituals could also feed conflict by turning the opinions and preferences of groups into 'sacred values' — absolute and non-negotiable beliefs that cannot be traded against material benefits such as money. For many Israelis, for example, one such value is the right to occupy the West Bank, whereas for many Palestinians it is the right to return to the villages from which they were expelled. In fact, Atran has found that financial offers to compromise on these sacred values makes them even more entrenched10.

As an example of how rituals can cause values and preferences to become sacralized, Atran points to his studies showing that, in the United States, people who attend church more frequently are more likely to consider the right to bear arms a sacred value11.

“Emotionally intense rituals have bound us together and pitted us against our enemies throughout the history of our species,” says Whitehouse. “It was only when nomadic foragers began to settle down did we discover the possibilities for establishing much larger societies based on frequently repeated creeds and rituals.”

The big question, he says, is whether this kind of unity can be extended to humanity at large. For Whitehouse, understanding the ways that rituals shape group behaviour is the first step towards finding out how they can be harnessed to dampen down conflict between groups. He hopes that such insights could help policy-makers to “establish new forms of peaceful cooperation, as well as bringing down dictators”.
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Article References:

1. Whitehouse, H. Modes of Religiosity: A Cognitive Theory Of Religious Transmission (AltaMira Press, 2004).
2. McQuinn, B. After the Fall: Libya's Evolving Armed Groups Small Arms Survey Working Paper 12 (Small Arms Survey, 2012).
3. Atkinson, Q. D. & Whitehouse, H. Evol. Hum. Behav. 32, 50–62 (2011).
4. Turchin, P., Whitehouse, H., Francois, P., Slingerland, E. & Collard, M. Cliodynamics 3, 271–293 (2012).
5. Legare, C. H & Souza, A. L. Cognition 124, 1–15 (2012).
6. Wiltermuth, S. S. & Heath, C. Psychol. Sci. 20, 1–5 (2009).
7. Sosis, R. & Ruffle, B. J. Curr. Anthropol. 44, 713–722 (2003).
8. Ruffle, B. J. & Sosis, R. J. Econ. Behav. Org. 60, 147–163 (2006).
9. Ginges, J., Hansen, I. & Norenzayan, A. Psychol. Sci. 20, 224–230 (2009).
10. Ginges, J., Atran, S., Medin, D. & Shikaki, K. Proc. Natl Acad. Sci USA 104, 7357–7360 (2007).
11. Sheikh, H., Ginges, J., Colman, A. & Atran, S. Judgm. Decis. Mak. 7, 110–118 (2012).

References:

Jones, Dan. 2013. “Social evolution: The ritual animal”. Nature. Posted: January 23, 2013. Available online: http://www.nature.com/news/social-evolution-the-ritual-animal-1.12256

Journal Reference:

Nature 493, 470–472 (24 January 2013) doi:10.1038/493470a

Sunday, February 3, 2013

Muslim thought on evolution takes a step forward

A high-quality debate of a sensitive topic did not disappoint, as all panellists bar one accepted the scientific consensus

An imam of an east London mosque, Usama Hasan, received a death threat for arguing in support of human evolution two years ago. On Saturday, London played host to a riveting intrafaith dialogue on Islam's stance on the theory of evolution. The east London imam was one of the speakers – but this time there were others who shared his viewpoint.

The event, organised by the Deen Institute, was titled Have Muslims Misunderstood Evolution? The speakers included an evolutionary biologist, a biological anthropologist, two theologians and a bona fide creationist.

It lasted seven hours, yet almost everyone stayed till the end. There were more than 850 people in the audience and even though the topic was sensitive and controversial, there was no heckling or disruption. At least from my limited interactions, it seemed that the audience was comprised mostly of young professionals. Most had no strong opinion, but their interest was evident as they were willing to spend their entire Saturday hearing about Muslim positions on evolution.

They were not disappointed.

Conversations at events such as these are often derailed by the unscientific rhetoric and common misconceptions of creationists. The success of this event related to the fact that all panellists, with the exception of a creationist, more or less accepted the scientific consensus on evolution. This allowed the discussion to centre on the question: can Muslims reconcile human evolution with their faith?

I think it is important for Muslims (and non-Muslims) to know that there are Muslim scientists who not only understand evolution, but have also thought about its implications for their own personal religious beliefs. Ehab Abouheif is an evolutionary biologist who holds the Canada research chair at McGill University and works on ant evolution. He laid out the scientific case for biological evolution and spoke about the need for Muslims to understand this bedrock principle of modern biology. He used the example of his own personal faith to counter the misconception that one cannot reconcile evolution with Islam.

Fatimah Jackson, an African American convert to Islam, is professor of biological anthropology at the University of North Carolina. Her research focuses on anthropological genetics and human biological and biocultural variability. She knew and taught evolution before her conversion to Islam in the 1970s and has never considered the two to be in conflict. She took the position that science only tells us "how" things happen, and not "why".

Both Abouheif and Jackson are outstanding researchers who accept the mainstream scientific view on evolution. They are excited about their work and unwavering in defence of their faith. They are role models for any budding Muslim scientist.

The London event also featured a theological debate between Usama Hasan and Shaykh Yasir Qadhi. Hasan is a fellow of the Royal Astronomical Society and is the imam who was threatened two years ago for his support for human evolution. He reiterated his position and argued that there was indeed room in Islamic theology to accommodate human evolution.

Qadhi, on the other hand, accepted all of evolution except where it applies to humans. However, he conceded that the "maximum we can go" from an Islamic theological perspective is to say that God inserted Adam in the natural order. To explain his position, he used the example of dominos. He asserted that Adam was the last domino placed directly by God. From his perspective, believers would see this last domino as a miracle of God, whereas non-believers would see a causal connection from all the other dominos. This way, the miracle of Adam is preserved theologically.

The high quality of scientific and theological discussion exposed the shallowness of Islamic creationists, such as Harun Yahya. One of his acolytes, Oktar Babuna, presented his arguments from Istanbul, via the internet. He kept on pointing to fossils as evidence that species have never changed in history. He also discounted any historical changes in the DNA. Babuna's arguments were countered earlier on by both Abouheif and Jackson. But he unintentionally served as a comic relief, when the audience realised that after several hours of discussion, almost all of his responses included the mention of "fossils", irrespective of the topic of discussion.

Babuna aside, this was a serious debate on an important topic. The rejection of evolution in the face of scientific consensus stands as a Galileo moment for Islam. However, the tone of the debate and the quality of intellectual exchange at the London event is encouraging and it shows modern Muslims have the maturity to address a perceived challenge from a scientific idea.
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References:

Hameed, Salman. 2013. “Muslim thought on evolution takes a step forward”. The Guardian. Posted: January 11, 2013. Available online: http://www.guardian.co.uk/commentisfree/belief/2013/jan/11/muslim-thought-on-evolution-debate

Wednesday, April 25, 2012

Excessive Worrying May Have Co-Evolved With Intelligence

Worrying may have evolved along with intelligence as a beneficial trait, according to a recent study by scientists at SUNY Downstate Medical Center and other institutions. Jeremy Coplan, MD, professor of psychiatry at SUNY Downstate, and colleagues found that high intelligence and worry both correlate with brain activity measured by the depletion of the nutrient choline in the subcortical white matter of the brain. According to the researchers, this suggests that intelligence may have co-evolved with worry in humans.

"While excessive worry is generally seen as a negative trait and high intelligence as a positive one, worry may cause our species to avoid dangerous situations, regardless of how remote a possibility they may be," said Dr. Coplan. "In essence, worry may make people 'take no chances,' and such people may have higher survival rates. Thus, like intelligence, worry may confer a benefit upon the species."

In this study of anxiety and intelligence, patients with generalized anxiety disorder (GAD) were compared with healthy volunteers to assess the relationship among intelligence quotient (IQ), worry, and subcortical white matter metabolism of choline. In a control group of normal volunteers, high IQ was associated with a lower degree of worry, but in those diagnosed with GAD, high IQ was associated with a greater degree of worry. The correlation between IQ and worry was significant in both the GAD group and the healthy control group. However, in the former, the correlation was positive and, in the latter, the correlation was negative. Eighteen healthy volunteers (eight males and 10 females) and 26 patients with GAD (12 males and 14 females) served as subjects.

Previous studies have indicated that excessive worry tends to exist both in people with higher intelligence and lower intelligence, and less so in people of moderate intelligence. It has been hypothesized that people with lower intelligence suffer more anxiety because they achieve less success in life.
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References:

Science Daily. 2012. "Excessive Worrying May Have Co-Evolved With Intelligence". Science Daily. Posted: April 12, 2012. Available online: http://www.sciencedaily.com/releases/2012/04/120412153018.htm

Jeremy D. Coplan, Sarah Hodulik, Sanjay J. Mathew, Xiangling Mao, Patrick R. Hof, Jack M. Gorman, Dikoma C. Shungu. The Relationship between Intelligence and Anxiety: An Association with Subcortical White Matter Metabolism. Frontiers in Evolutionary Neuroscience, 2012; 3 DOI: 10.3389/fnevo.2011.00008

Sunday, March 18, 2012

Forget fittest, it's survival of the most cultured

Evolutionary biologist Mark Pagel enters tricky terrain to argue that social structures are key to human evolution in Wired for Culture

FOR decades, proponents of the power of culture in human development have been tribal enemies of those who champion the power of evolution. The former have been vilified for portraying humans as blank slates; the latter scorned for embracing genetic determinism. The middle ground was no-man's-land.

Now, at last, the war might be over. A consensus is emerging that humans have an impressive capacity for open-ended change, much as culturalists have claimed, but that this is a result of genetic evolution - and is itself an evolutionary process. Culture can now be approached from an evolutionary perspective, while evolutionists have much to learn from the "natural historians" of cultures.

Mark Pagel, a professor of evolutionary biology at the University of Reading, UK, is well placed to write on these recent developments. In Wired for Culture he frames cultural development in the language of Richard Dawkins's selfish gene theory, in which genes are replicators that build individual bodies as vehicles for their own survival. Dawkins famously coined the term "meme" as the cultural analogue of a gene. Pagel's argument goes one step further.

Memes, he says, have built vehicles around themselves made up of groups of people. We live inside "cultural survival vehicles" that allow us to collectively survive and reproduce in any given environment. Pagel argues that there are thousands of such vehicles, each adapted to different environments, exemplified by humanity's wealth of languages. Genetically we remain a single species, but culturally we are worlds apart, comparable to dinosaurs, birds and mammals.

Wired for Culture explores the implications of the emerging consensus across the breadth of human experience, from religion, the arts and economics, through consciousness, deception, conflict and the very idea of truth.

Pagel writes well, and the ideas within the book are engagingly expressed. But in a book which overcomes the traditional separation between evolutionists and culturalists, Pagel has difficulty surmounting tribal boundaries within his own field.

Evolutionary biologists are divided on the subject of group selection - the view that adaptations can evolve "for the good of the group". Acceptance of group selection in the context of selfish gene theory hinges on the question of whether groups can be vehicles of selection. Dawkins and other selfish gene theorists such as Daniel Dennett are sceptical about this possibility, and their scepticism extends to ideas about culture and religion. Indeed, both have famously argued that religious memes are like parasites that are detrimental to their human "hosts".

Pagel departs from Dawkins and Dennett by portraying cultures as group-level survival vehicles, correctly in my opinion, but seems to think that in employing the language of selfish gene theory he is rejecting group selection. This is a failure of translation. When he makes statements such as: "Any group that failed to acquire these cultural forms could find themselves in competition with others that had", he is invoking group selection, pure and simple.

This is an issue for everyone: books like The Selfish Gene had a huge impact because they brought issues like group selection into the public realm. Much of the work Pagel cites openly acknowledges the role of group selection in the evolution of human society, and to deny its importance is a disservice to public understanding. It is a pity that Pagel, whose speciality is the evolution of languages, cannot seem to translate among the languages spoken within his own discipline.

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References:

Wilson, David Sloan. 2012. "Forget fittest, it's survival of the most cultured". New Scientist. Posted: March 5, 2012. Available online: http://www.newscientist.com/blogs/culturelab/2012/03/forget-fittest-its-survival-of-the-most-cultured.html

Thursday, December 29, 2011

Was Darwin wrong about emotions?

Contrary to what many psychological scientists think, people do not all have the same set of biologically "basic" emotions, and those emotions are not automatically expressed on the faces of those around us, according to the author of a new article published in Current Directions in Psychological Science, a journal published by the Association for Psychological Science. This means a recent move to train security workers to recognize "basic" emotions from expressions might be misguided.

"What I decided to do in this paper is remind readers of the evidence that runs contrary to the view that certain emotions are biologically basic, so that people scowl only when they're angry or pout only when they're sad," says Lisa Feldman Barrett of Northeastern University, the author of the new paper.

The commonly-held belief is that certain facial muscle movements (called expressions) evolved to express certain mental states and prepare the body to react in stereotyped ways to certain situations. For example, widening the eyes when you're scared might help you take in more information about the scene, while also signaling to the people around you that something dangerous is happening.

But Barrett (along with a minority of other scientists) thinks that expressions are not inborn emotional signals that are automatically expressed on the face. "When do you ever see somebody pout in sadness? When it's a symbol," she says. "Like in cartoons or very bad movies." People pout when they want to look sad, not necessarily when they actually feel sad, she says.

Some scientists have proposed that emotions regulate your physical response to a situation, but there's no evidence, for example, that a certain emotion usually produces the same physical changes each time it is experienced, Barrett says. "There's tremendous variety in what people do and what their bodies and faces do in anger or sadness or in fear," she says. People do a lot of things when they're angry. Sometimes they yell; sometimes they smile.

"Textbooks in introductory psychology says that there are about seven, plus or minus two, biologically basic emotions that have a designated expression that can be recognized by everybody in the world, and the evidence I review in this paper just doesn't support that view," she says. Instead of stating that all emotions fall into a few categories, and everyone expresses them the same way, Barrett says, psychologists should work on understanding how people vary in expressing their emotions.

This debate isn't purely academic. It has consequences for how clinicians are trained and also for the security industry. In recent years there's been an explosion of training programs that are meant to help security officers of all kinds identify people who are up to something nefarious. But this training might be misguided, Barrett says. "There's a lot of evidence that there is no signature for fear or anger or sadness that you could detect in another person. If you want to improve your accuracy in reading emotion in another person, you have to also take the context into account."

Incidentally, the theory that emotional expressions evolved for specific functions is normally attributed to Charles Darwin, in his book The Expression of the Emotions in Man and Animals. But Darwin didn't write that emotional expressions are functional. "If you're going to cite Darwin as evidence that you're right, you'd better cite him correctly," Barrett says. Darwin thought that emotional expressions – smiles, frowns, and so on –were akin to the vestigial tailbone – and occurred even though they are of no use.
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References:

EurekAlert. 2011. "Was Darwin wrong about emotions?". EurekAlert. Posted: December 13, 2011. Available online: http://www.eurekalert.org/pub_releases/2011-12/afps-wdw121311.php

Thursday, December 8, 2011

Why does religion keep telling us we're bad?

Evolution has carried us a long way, but we can become complacent, which is where religious admonitions come in

When I told my father I was going to Cambridge to give a talk on the question of whether humans were good or bad, he looked at me sternly over his glasses. "You know what the answer is, don't you?" Total depravity and filthy rags he was hoping I would say of our nature – the first is a primary tenet of Calvinist doctrine, and the second is a phrase from Isaiah. I was about to say that we are at our root neither good nor bad, but pulled in contrary directions with the ability to make a decision. So I knew we were in for … a discussion.

From an evolutionary perspective, considering other social species on this earth, it is remarkable that a bunch of unrelated adult males can sit on a plane together for seven hours in the presence of fertile females, with everyone arriving alive and unharmed at the end of it. We could be a lot worse than we are, according to our common notions of right and wrong. We have certainly come a long way towards becoming a co-operative, sympathetic, even loving species.

Granted, this depends on your perspective: if you're a biologist, as I am, you might notice how far we've come. If you're a theologian, perhaps the more salient realisation is how far we haven't. The meeting place between these perspectives is that we are full of conflicting tendencies and inconsistencies in our attitudes and behaviour. So we would do well to ask why this conflict exists, in addition to arguing whether we've done well or poorly in it.

At several points in our evolutionary history, sources of conflict have arisen, leading to moral tension and ambivalence. Perhaps the oldest and most significant is the fact that we as individuals have gained by looking out for ourselves in competition with others, but that we also have depended on our social groups and so gained by supporting and contributing to the stability of those groups. From this ancient situation eventually arose the tug of war between selfishness and altruism that is a common aspect of our moral experience.

We should realise, however, that these often contrary tendencies both evolved in our nature through natural selection based on individual advantage. Even more importantly, though, we should realise that an evolutionary mechanism does not necessarily trickle down into our intentions and motives – caring for each other may have evolved by natural selection, but this does not rule out the possibility of genuine love and kindness.

Furthermore, we can extend our moral consideration far beyond what was beneficial to our ancestors – to humanity as a whole, even to the natural world. This leads to another important source of angst in our moral life: the difference between attitudes and behaviours that would have been advantageous for our ancestors, and those we wish to embrace and promote today. We need not wait for evolutionary adaptation to catch up with our vision of goodness, if ever it would. We can do this on our own, but it requires that familiar battle between what we feel like doing and what we know we ought to do. The former very often comes from our past, our evolutionary heritage, whereas the latter comes from whatever is most important to us.

Many of the evolutionarily savvy among us have chosen one of two roads with regard to describing our moral nature. One is the comforting notion that we are generally prosocial nice folks except for those odd meanies who must be explained as having some strange allele or bad childhood environment. The other common option is a descent into moral scepticism or nihilism where nothing matters anyway because it's all just a product of our evolution. These alternatives together look remarkably like a sour grapes attitude: either we are fundamentally good, or else forget it there's no such thing as good and bad. The main reason for Isaiah's admonition to remember how we fall short, as for most Jewish and Christian moral admonitions come to think of it, is to counteract our tendency to look at ourselves with rose-coloured glasses and become complacent. It looks like we could use a dose of my father's old time religion after all.
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References:

Lahti, David. 2011. "Why does religion keep telling us we're bad?". The Guardian. Posted: November 22, 2011. Available online: http://www.guardian.co.uk/commentisfree/belief/2011/nov/22/religion-bad-evolution-religious-admonitions

Tuesday, November 15, 2011

Shared Genes With Neanderthal Relatives: Modern East Asians Share Genetic Material With Prehistoric Denisovans

During human evolution our ancestors mated with Neanderthals, but also with other related hominids. In this week's online edition of Proceedings of the National Academy of Sciences, researchers from Uppsala University are publishing findings showing that people in East Asia share genetic material with Denisovans, who got the name from the cave in Siberia where they were first found.

"Our study covers a larger part of the world than earlier studies, and it is clear that it is not as simple as we previously thought. Hybridization took place at several points in evolution, and the genetic traces of this can be found in several places in the world. We'll probably be uncovering more events like these," says Mattias Jakobsson, who conducted the study together with Pontus Skoglund.

Previous studies have found two separate hybridization events between so-called archaic humans (different from modern humans in both genetics and morphology) and the ancestors of modern humans after their emergence from Africa: hybridization between Neanderthals and the ancestors of modern humans outside of Africa and hybridization between Denisovans and the ancestors of indigenous Oceanians. The genetic difference between Neandertals and Denisovans is roughly as great as the maximal level of variation among us modern humans.

The Uppsala scientists' study demonstrates that hybridization also occurred on the East Asian mainland. The connection was discovered by using genotype data in order to obtain a larger data set. Complete genomes of modern humans are only available from some dozen individuals today, whereas genotype data is available from thousands of individuals. These genetic data can be compared with genome sequences from Neandertals and a Denisovan which have been determined from archeological material. Only a pinky finger and a tooth have been described from the latter.

Genotype data stems from genetic research where hundreds of thousands of genetic variants from test panels are gathered on a chip. However, this process leads to unusual variants not being included, which can lead to biases if the material is treated as if it consisted of complete genomes. Skoglund and Jakobsson used advanced computer simulations to determine what this source of error means for comparisons with archaic genes and have thereby been able to use genetic data from more than 1,500 modern humans from all over the world.

"We found that individuals from mainly Southeast Asia have a higher proportion of Denisova-related genetic variants than people from other parts of the world, such as Europe, America, West and Central Asia, and Africa. The findings show that gene flow from archaic human groups also occurred on the Asian mainland," says Mattias Jakobsson.

"While we can see that genetic material of archaic humans lives on to a greater extent than what was previously thought, we still know very little about the history of these groups and when their contacts with modern humans occurred," says Pontus Skoglund.

Because they find Denisova-related gene variants in Southeast Asia and Oceania, but not in Europe and America, the researchers suggest that hybridization with Denisova man took place about 20,000-40,000 years ago, but could also have occurred earlier. This is long after the branch that became modern humans split off from the branch that led to Neandertals and Denisovans some 300,000-500,000 years ago.

"With more complete genomes from modern humans and more analyses of fossil material, it will be possible to describe our prehistory with considerably greater accuracy and richer detail," says Mattias Jakobsson.
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References:

Science Daily. 2011. "Shared Genes With Neanderthal Relatives: Modern East Asians Share Genetic Material With Prehistoric Denisovans". Science Daily. Posted: October 31, 2011. Available online: http://www.sciencedaily.com/releases/2011/10/111031154119.htm

Journal Reference:

1. Pontus Skoglunda and Mattias Jakobssona. Archaic human ancestry in East Asia. Proceedings of the National Academy of Sciences, 2011 DOI: 10.1073/pnas.1108181108

Tuesday, October 18, 2011

Humans Are Still Evolving, Study Says

Humans, like all other organisms on Earth, are subject to the pressures of evolution. New research suggests that even in relatively modern societies, humans are still changing and evolving in response to the environment.

"Whether humans could or could not evolve in modern times could have interesting implications," study researcher Emmanuel Milot, of the University of Quebec in Montreal, told LiveScience. It could help us understand changing trends for the different traits of a population.

By studying an island population in Quebec, the researchers found a genetic push toward younger age at first reproduction and larger families. This is the first direct evidence of natural selection in action in a relatively modern human population.

Past studies have hinted our species continues to evolve, with research showing changes to hundreds of genes in the human genome over the past 10,000 years; in addition, skull measurements suggest our brains have been shrinking over the last 5,000 years or so.

An island population

The study used data from 30 families who settled on île aux Coudres, located in the St. Lawrence River outside of Quebec City, between 1720 and 1773. A church on the island held historical records of all births, deaths and marriages on the island, from which researchers were able to build intensive family trees.

The researchers analyzed the data from women who married between 1799 and 1940, comparing their relations, any social, cultural or economic differences, and the age they had their first child.

The researchers found that over a 140-year period, age at first reproduction dropped from 26 to 22, with somewhere between 30 percent and 50 percent of this variation being explained by genetic variation in the population, not by other factors, such as changes in cultures or social attitudes.

"We think, traditionally, that the changes in human population are mainly cultural, which is why a non-genetic hypothesis is given priority over a genetic or evolutionary hypothesis, whether or not there is data to support that," Milot said. "We have data that we analyzed from the genetic and nongenetic point of view, and we find that the genetic factors are stronger."

Naturally selected population

Because of the populations' lack of birth control, families in this population ended up being very large, and since fertility wasn't altered by outside influences, each couple was likely to reach maximum fertility.

The researchers didn't look at which genes might have changed over time, but they suggest reasons for the age change could include differences in fertility and how early a woman hits puberty, or even heritable personality traits that would nudge a woman to procreate earlier. These genetic factors would be changing in response to the natural selection for a higher number of kids overall.

"In that particular population, selective pressure seemed pretty constant for the study period," Milot said. "Maybe it has to do because it has a newly founded population and it was not disadvantageous to have big families."

A newly founded population would have the resources to support large families, and more kids mean the higher likelihood that one's genes would survive well into the future.

Evolving humans

Seeing natural selection in modern populations is incredibly difficult. Because this population was pretty highly related and relatively cut off from outside populations, the correlation between genetic factors and age at first reproduction was easier to see.

"What we learn from that population is that evolution is possible in relatively modern times in modern humans," Milot said. "Where it is going to occur and in what ways is a different question."

Steve Stearns, a researcher from Yale University who wasn't involved in the study, told LiveScience in an email that the work "is an important advance, because it demonstrates a genetic response to selection in a recent, almost a contemporary, human population."
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References:

Welsh, Jennifer. 2011. "Humans Are Still Evolving, Study Says". Live Science. Posted: Available online: http://www.livescience.com/16358-human-evolution-natural-selection.html