Paleolithic Papers #29

Genus Homo:

Rock art from Croatia from circa 34,000 years ago is figurative in nature.

Stone tools were recycled to new uses at a cave in Israel during the late Lower Paleolithic.

Hunter gatherers don't live in 'small' societies.

H. sapiens (Modern Humans):

Brain sizes have shrunk 10% in the last 40,000 years.

There is evidence of starchy food cooked in South Africa during the Mesolithic.

Is this the earliest known footprint from a human in the Americas?

H. neanderthalensis (Neandertals):

The Sima de los Huesas hominins get their age bracketed.

The first Neandertal fossil from Serbia has been found.

Could have aridification helped wipe out the neandertals?

Denisovans:

The Denisovans were two populations, at least, and may have actually been two different species.

A Denisovan jaw bone found in Tibet shows Denisovans colonized the 'roof of the world' long before modern humans did.  The jaw bone also starts to show what the Denisovans looked like.

H. antecessor:

H. antecessor was, at least once, a cannibal.

H. heidelbergensis:

Evidence from reexamining bovid remains from South Africa suggest active hunting was import for H. heidelbergensis.

H. luzonensis:

H. luzonensis, a new hominin from Luzon island of the Philippines, has been discovered. This hominin was another miniature standing at about an estimated 1.2m (5 ft). It may have suffered from island dwarfing like H. floresiensis, the so-called Hobbit.  John Hawks comments.

Hualongdong Hominin:

A hominin from China has a mosaic of primitive and modern features.  Some are claiming this is proof of the multiregional hypothesis.

H. erectus:

Evidence of what mammals H. erectus ate in Italy prior to 1.3 million years ago.

The dispersal routes out of Africa for hominins are explored in Sudan looking for stone tools.  John Hawks comments.

H. naledi:

Cranial remains from the Lesedi Chamber of the Rising Star Cave show some variation from the other fossils, but by and large appear to be more of H. naledi.

H. habilis:

The KNM-ER 64060 fossil mandible appears to be from H. habilis rather than H. erectus.

Genus Australopithecus:

A. sediba:

A sediba does not appear to be ancestral to modern humans.

META:

Man the Runner hypothesis is back again.

A troop of chimps deprived a leopard of its kill: how does that help model early hominins?

The history of human evolution can be seen in your face.

How important was the east african coastal forest for human evolution?

Basal ancestors of Humanity were upright apes.

Plovers Lake paleogenetics data might have been contaminated by modern people.

Paleolithic Papers #23

Genus Homo:

The modern human hand was almost certainly around by 500,000 years ago, predating modern humans by 300,000 years.

The deactivation of the Cmah gene two to three million years ago appears to have given hominins a leg up by increasing endurance and improving running speeds.

H. sapiens:

When DID modern humans reach southeast asia and sahul?

The revised timeline of data from the Liang Bua cave may suggest modern humans made it to Flores by 46 kya.

The Levant had a humid period between 44kya and 55 kya.  That may be what helped modern humans disperse out of Africa.

An abstract piece of art appears to have been found in a cave in South Africa dating from 73,000 years ago.

Using ZooMS to understand the bone tools of the twilight of the Pleistocene in North Africa.

Humans actually share better than other primates.

Beer before agriculture.  Maybe.  However, beer dates from the twilight of the Pleistocene in Israel.  If not older.

Neandertals:

The early dates for the Neandertal Art might be wrong.  Some are disputing them.

Could cooking and fire be how modern humans outcompeted Neandertals?

How much did the climate cycles impact the replacement of Neandertals by modern humans in Europe?

Neandertal brains were bigger than modern humans, but not necessarily better.

Denisovans:

Meet Denny.  She is a 13 year old girl who had a Neandertal mother and a Denisovan father.

The cave where Denny came from has given up 4 more bones (not hers).  Dr. John Hawks comments.

Aroeria Hominin:

The bony labyrinth of this hominin appears to be more primitive than in Neandertals.  This could be a new hominin or an example of Homo heidelbergensis.

META:

Evolution of the hominin foot and how it relates to bipedalism.

How DID humans evolve their 'smarts?'

Two to three million years ago, human ancestors had genetic change that improved their running capability.

Studying the African Neolithic Transition Through Genetics

Scientists from the Institut Pasteur set out to understand how the demographic changes associated with the Neolithic transition also influenced the efficacy of natural selection. By comparing the genome diversity of more than 300 individuals from groups of forest hunter-gatherers (pygmies) and farmers (Bantu-speaking peoples), from western and eastern Central Africa, they discovered that the reason pygmies did not suffer from excessive deleterious mutations was because of their genetic diversity and their admixture with the Bantu peoples.

Research into the diversity of the human genome and any rare or frequent mutations is vital in identifying mutations that increase susceptibility to "complex" diseases, such as infectious or autoimmune disorders. "The elimination of these mutations that are harmful for human health is largely conditioned by the evolutionary history of populations, especially their demographic fluctuations," explains Lluis Quintana, Head of the Human Evolutionary Genetics Unit and author of the study. Throughout their history, human populations have undergone significant and extremely varied changes in terms of numbers of individuals, giving rise to differences in the number and severity of mutations carried by these populations. The accumulation of disease-causing genetic variants, known as the "burden of deleterious mutations", varies from one population to another depending on its past. "The aim of our project is to understand how demographic events such as the rise and fall in numbers of individuals, as well as genetic admixtures, have had an impact on the efficacy of some evolutionary mechanisms such as purifying selection."

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Linguists or Nationalists: Who was Right About the Origin of Indian Civilization?

A CENTURY and a half ago linguists invented a new map of the world. Their research showed that a single family tree stretches its branches almost unbroken across most of Eurasia: from Iceland to Bangladesh, most people speak languages descended from “Proto-Indo-European”. The philologists had a theory to explain why Sanskrit, the ancient forebear of Hindi, has closer cousins in Europe than in south India. They speculated that at some point before the composition of the Vedas, the oldest texts of Hinduism, an Aryan people had migrated into India from the north-west, while their kin pushed westward into Europe.

Long before the Nazis dreamed of an exalted master race, imperialists seized on what some dubbed the “Aryan invasion” theory to paint Britain’s rule of India as the extension of a “natural” order. Indians, too, found a use for it. Caste-bound Hindu conservatives declared that the paler-skinned intruders must be ancestors of higher-caste Brahmins and Kshatriyas. Such talk stirred a backlash in southern India, where generally darker-skinned speakers of Dravidian languages were urged to see themselves as a separate nation.

Hindu nationalists took a different tack. The West, some said, had made up the theory to set Hindus against each other. Christian missionaries and communists were using it to stoke caste hatred and so to recruit followers, they claimed. Worse, the theory challenged an emerging vision of Mother India as a sacred Hindu homeland. If the first speakers of Sanskrit and the creators of the Vedas had themselves been intruders, it was harder to portray later Muslim and Christian invaders as violators of a purity that good Hindus should seek to restore. So it was that some proposed an alternative “Out of India” theory. This held that the original Aryans were in fact Indians, who carried their Indo-European language and superior civilisation to the West.

[...]

An accumulating pile of research using DNA from both ancient human remains and modern people indicates strongly that, beginning around 2000BC, north-west India was indeed infused with new blood. The newcomers appear to have shared the same roots in what is now southern Russia as did the invaders of a similar-sized peninsula to the west called Europe. Strikingly, too, the genetic markers identifying this group seem to be far more prevalent among modern north Indian Brahmins than among other Indians.

Because of the difficulty in collecting ancient DNA, such research has until recently relied on relatively few samples. But an international team of 92 scholars, including David Reich, a geneticist at Harvard University who has pioneered techniques to analyse DNA more quickly and precisely, is set to publish data recovered from 362 “ancient individuals” from across South and Central Asia. Among their conclusions: there was probably an early migration of agriculturalists into India from what is now Iran, around 4000BC, and this was followed two millennia later—just before the Vedic Age—by a large influx from what is now southern Russia.

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2nd link.

Paleogenetics Shed Light on Ancestry of the Inca

A multinational South American team from Peru, Brasil and Bolivia led by the Universidad de San Martin de Porres at Lima, Peru, published the first genetic study on the modern descendants of the imperial Inka lineages in the journal Molecular Genetics and Genomics. This work supported by funds from the Genographic Project (Geno 2.0), shows new insights about the Inkas origins and lineages.

The Inka people arrived to Cusco valley and in a few centuries they built the Tawantinsuyu, the largest empire in the Americas. The Tawantinsuyu was the cultural climax of 6,000 years of Central Andes civilizations overlapping modern countries of Peru, Bolivia, Ecuador, the South of Colombia and the North of Argentina and Chile. In contrast with the richness of archeological and cultural evidence, pre Columbian history vanishes in time as it intermingles with myths due to the lack of writing systems before the arrival of the European chroniclers. Very little is known about the Inka origins and some genetic information could help reconstruct part of their history. Unfortunately the mummies and bodily remains of the Inka emperors, worshiped as gods, were burnt and buried in unknown locations due to religious and political persecution by the Christian Conquistadors and Inquisitors, so no direct material remain to study their DNA. "Thus for now, only the genetic analysis of modern families of Inka descent could provide some clues about their ancestors" remarks geneticist Jose Sandoval, first author, working at Universidad de San Martin de Porres at Lima, Peru.

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Inhabitants of Vanuatu Were Replaced, but Their Language Lives on

The study, published in Nature Ecology & Evolution and led by a multidisciplinary research team at the Max Planck Institute for the Science of Human History (MPI-SHH) together with researchers in France, Australia, New Zealand, Germany and Vanuatu, reveals that migrations of people from the Bismarck Archipelago in Oceania to the previously settled islands of the Pacific began as early as 2,500 years ago, much earlier than previously thought. The Remote Oceanian island nation of Vanuatu is the gateway to the rest of the Pacific and understanding its demographic history is critical to uncovering that of the wider region. The earliest inhabitants of Vanuatu, arriving about 3,000 years ago, were the Lapita peoples who spoke a form of Austronesian language and who had largely East Asian genetic ancestry. But Vanuatu's contemporary population has largely Near Oceanian heritage, showing that over time the genetic ancestry of the early inhabitants was mostly replaced by that of Bismarck Archipelago migrants, who began arriving very soon after initial settlement. Yet the original Austronesian language persisted and over 120 descendant languages continue to be spoken today, making Vanuatu the per capita most linguistically diverse place on Earth. Vanuatu therefore presents an unprecedented case, where a population's genetic ancestry but not its languages were replaced. Through analyses of new ancient and modern genome-wide data, the researchers show that rather than occurring in one wave, the genetic replacement was long and complex, likely the result of a sustained long-distance contact between Near and Remote Oceania. This provides demographic support for a model from historical linguistics, in which the initial Austronesian language of Vanuatu survived by being continually adopted by incoming Papuan migrants.

The Austronesian Expansion, which began around 5,500 years ago likely in modern-day Taiwan, was the most geographically extensive dispersal of farming peoples in prehistory, ultimately carrying people as far west as Madagascar and all the way east to Rapa Nui. These seafaring Neolithic people initially expanded out across Island Southeast Asia, carrying farming technology and a major branch of the Austronesian language family, eventually reaching Near Oceania where they encountered the indigenous Papuan peoples of New Guinea and the Bismarck Archipelago. The initial settlement east beyond the Solomon Islands and out into Remote Oceania only began around 3,000 years ago, with Austronesian-speaking groups associated with the Lapita pottery culture rapidly expanding east out to Vanuatu, New Caledonia, Fiji and the islands of Western Polynesia. A previous ancient DNA study of Lapita burial sites has shown that these earliest inhabitants had East Asian ancestry with negligible evidence of Papuan genetic admixture. But the present-day genetic make-up of Remote Oceania suggests at least some degree of Papuan ancestry, meaning there must have been subsequent Papuan migration and admixture into the Pacific from Near Oceania.

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There was a Huge Steppe Migration into Europe Circa 3,300 BC

Consider the unexpected movement of people who originally lived on the steppes of Central Asia, north of the Black and Caspian seas. About 5,300 years ago, the local hunter-gatherer cultures were replaced in many places by nomadic herders, dubbed the Yamnaya, who were able to expand rapidly by exploiting horses and the new invention of the cart, and who left behind big, rich burial sites.

Archeologists have long known that some of the technologies used by the Yamnaya later spread to Europe. But the startling revelation from the ancient DNA was that the people moved, too - all the way to the Atlantic coast of Europe in the west to Mongolia in the east and India in the south. This vast migration helps explain the spread of Indo-European languages. And it significantly replaced the local hunter-gatherer genes across Europe with the indelible stamp of steppe DNA, as happened in Britain with the migration of the Bell Beaker people to the island.

"This whole phenomenon of the steppe expansion is an amazing example of what ancient DNA can show," says Reich. And, adds Cunliffe, "no one, not even archeologists in their wildest dreams, had expected such a high steppe genetic content in the populations of northern Europe in the third millennium B.C."

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The Copper Age Iberian Bell Beaker Culture Exported Culture & Technology, not Genes

Prehistoric Iberians 'exported' their culture throughout Europe, reaching Great Britain, Sicily, Poland and all over central Europe in general. However, they did not export their genes. The Beaker culture, which probably originated in Iberia, left remains in those parts of the continent. However, that diffusion was not due to large migrations of populations that took this culture with them. These are the conclusions of an international study in which the Spanish National Research Council (CSIC) was involved. Its findings, published in the journal Nature, indicate no evidence of any genetic outflow from Iberia to those areas has been discovered. "Therefore, the diffusion of the Beaker culture from Iberia is the first example of a culture being transmitted as an idea, basically due to a question of social prestige (since it was associated with the virtues of being virile and of being warriors), which is why it is adopted by other populations", indicates researcher Carles Lalueza-Fox, from the Institute of Evolutionary Biology, a mixed research centre run by CSIC and the Pompeu Fabra University, in Barcelona, Spain.

Between 4,700 and 4,400 years ago, a new type of bell-shaped beaker pottery was introduced throughout western and central Europe. For more than a century, archaeologists have been trying to determine whether the spread of this beaker pottery - and the (Beaker) culture associated with it - represented a large-scale migration or whether it was due simply to the exchange of new ideas. Now, this new study, which includes DNA data from 400 prehistoric skeletons collected from sites across Europe, resolves the debate of whether the spread was due to migrations or ideas, indicating that both arguments are correct. The findings show that the culture which produced these bell-shaped beakers extended from Iberia to central Europe without a significant movement of populations, although the Beaker culture would spread to other places through migrations at a later date.

The study, whose first author is the Spanish researcher Íñigo Olalde, a geneticist at Harvard Medical School, shows that once the (Bell) Beaker culture reaches the centre of Europe (around Germany and its surrounding area), it expands backwards to other places, notably to the British Isles. Yet, in this case, it does represent a migration, replacing around 90% of the population with it. "That is to say, the Neolithic people who built Stonehenge (and who had a greater genetic similarity with Neolithic Iberians than with those from Central Europe) almost disappear and are replaced by the populations from the Beaker culture from the Netherlands and Germany. This replacement is almost absolute in terms of the Y chromosome, which is transmitted by the paternal line, indicating an extreme reproductive bias, and therefore a previously unheard of social dominance. The backward flow also reaches other places such as Italy (at least in the north) and Iberia. I believe it is possible that this is also associated with the expansion of the Celtic or Proto-Celtic languages," Mr. Lalueza-Fox points out.

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The Caribbean Taino Have Modern Descendants

Origins and genetic legacies of the Caribbean Taino

Authors:

Schroeder et al

Abstract:

The Caribbean was one of the last parts of the Americas to be settled by humans, but how and when the islands were first occupied remains a matter of debate. Ancient DNA can help answering these questions, but the work has been hampered by poor DNA preservation. We report the genome sequence of a 1,000-year-old Lucayan Taino individual recovered from the site of Preacher’s Cave in the Bahamas. We sequenced her genome to 12.4-fold coverage and show that she is genetically most closely related to present-day Arawakan speakers from northern South America, suggesting that the ancestors of the Lucayans originated there. Further, we find no evidence for recent inbreeding or isolation in the ancient genome, suggesting that the Lucayans had a relatively large effective population size. Finally, we show that the native American components in some present-day Caribbean genomes are closely related to the ancient Taino, demonstrating an element of continuity between precontact populations and present-day Latino populations in the Caribbean.

John Hawks comments on the Science article about the above.

Bonobos and Chimpanzees had a Human/Neandertal Like Fling

A new whole-genome analysis of chimpanzees and bonobos reveals that these two great ape species likely interbred several hundred thousand years ago. A better understanding of the genetic flow between humans' closest living relatives could shed light on processes that might have played a recurring role in great ape evolution. While chimpanzees and bonobos are known to interbreed in captivity, the historic genetic flow between the two species in the wild is less clear. To gain better insights into possible historical gene flow between them, Marc de Manuel et al. analyzed the complete genomes of 10 bonobos and 65 chimpanzees. Significantly, more chimpanzees were included in their analysis, and from various regions in Africa, because previous genetic studies have suggested that four distinct species of chimpanzee exist. Following their analysis, the researchers observed clear evidence for gene flow between the two species, occurring between 200 and 550 thousand years ago, they estimate. Central, eastern, and Nigeria-Cameroon chimpanzees share significantly more genetic information with bonobos than do western chimpanzees, they report. What's more, similar to Neanderthal genetic patterns in humans, some background bonobo genetic information has been deleted in the chimpanzee genome, suggesting that some bonobo genes may have been disadvantageous for chimpanzees.

link.

Paleolithic Papers #9

Genus Homo:

A last humid refugium in Jordan during the Pleistocene provided for hominins.

Stone tools found from Middle Pleistocene Jordan have the blood of ducks, rhinos and others on them.

Upper Pleistocene Altamira cave has evidence of pigment processing in sea shells.

Does genus Homo need to be split?

Has the increased flow of blood to the brain been more important for the evolution of intelligence rather than brain size?

 H. neanderthalensis:

Is it NeanderTHAL or NeanderTAL? 

H. sapiens:

Evidence of people from the Pleistocene/Holocene Boundary in Brazil from a cave.

Modern humans have a gene allowing better tolerance of smoke than Neandertals. 

Modern human brains do not have a larger prefrontal cortex in relative terms than other primates, but do have an absolute larger number of neurons present.

The dispersal of modern humans into south east asia is tracked.

The first colonization of the Americas probably did NOT use the ice free corridor.

How DID humans occupy the Tibetan plateau?

Did the earliest modern humans acutally arise in China?

Genus Australopithecus:

The Laetoli hominin (A. afarensis?) had a gait distinctive from modern humans.

The earliest stone tools were used for more than just butchering.

A. afarensis:

Did Lucy die from falling from a tree? John Hawks is skeptical.

How flexible was A. afarensis' diet?

You can now 3d print Lucy's bones.

A. africanus:

The heel of A. africanus appears to have been more like a gorilla's than a chimp's.

 A sediba:

Cancer was found in one of the bones associated with A. sediba.

META:

A new analysis suggests the Piltdown Hoax was conducted by one person.

Dinosaurs Probably had Color Vision

Earlier this year, scientists used zebra finches to pinpoint the gene that enables birds to produce and display the colour red.

Now, a new study shows the same 'red gene' is also found in turtles, which share an ancient common ancestor with birds. Both share a common ancestor with dinosaurs.

The gene, called CYP2J19, allows birds and turtles to convert the yellow pigments in their diets into red, which they then use to heighten colour vision in the red spectrum through droplets of red oil in their retinas.

Birds and turtles are the only existing tetrapods, or land vertebrates, to have these red retinal oil droplets. In some birds and a few turtle species, red pigment produced by the gene is also used for external display: red beaks and feathers, or the red neck patches and rims of shells seen in species such as the painted turtle.

The scientists mined the genetic data of various bird and reptile species to reconstruct an evolutionary history of the CYP2J19 gene, and found that it dated back hundreds of millions of years in the ancient archelosaur genetic line - the ancestral lineage of turtles, birds and dinosaurs.

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Turtles are probably archosaurs, btw.

Ants Domesticated Fungus for Farming 60 to 55 Million Years ago During the Paleogene

A group of South American ants has farmed fungi since shortly after the dinosaurs died out, according to an international research team including Smithsonian scientists. The genes of the ant farmers and their fungal crops reveal a surprisingly ancient history of mutual adaptations. This evolutionary give-and-take has led to some species--the leafcutter ants--developing industrial-scale farming that surpasses human agriculture in its efficiency.

The key chapters of the history of ant agriculture are written into the genes of both the insects and their crop fungi. A team including Jacobus Boomsma, research associate at the Smithsonian Tropical Research Institute and biology professor at the University of Copenhagen with his colleagues there, Sanne Nygaard and Guojie Zhang, looked at the genes of seven species of farming ants and their associated fungi to understand how the partnership developed. In a study published in Nature Communications, the scientists found that 55 to 60 million years ago ants belonging to the tribe Attini switched from a hunter-gatherer lifestyle to subsistence farming of fungi that grew on decomposing, woody plant matter. The slow-growing fungi sustained tiny colonies of ants, but it was the first step toward agriculture on a much larger scale.

"The ants lost many genes when they committed to farming fungi," said Boomsma. This tied the fate of the ants to their food--with the insects depending on the fungi for nutrients, and the fungi increasing their likelihood of survival if they produced more nutritious crop. "It led to an evolutionary cascade of changes, unmatched by any other animal lineage studied so far."

The researchers found that around 25 million years ago one lineage of fungus-farming ants began cultivating fungi that produced tiny, protein-rich bulbs that the ants preferentially harvested. More nutritious food supported larger colonies, spurring even more advances in ant-fungus co-evolution until, 15 million years ago, the leafcutter ants emerged. Leafcutter ant species cut and sow their underground farms daily with fresh, green plant matter, cultivating a fully domesticated species of fungus on an industrial scale that can sustain colonies with up to millions of ants.

Domestication changed both partners in the relationship. Unlike its ancestors and present-day wild relatives, the leafcutter ants' fungus can no longer produce enzymes that digest woody plant matter, making it reliant on leafy greens brought in by the ants. In turn, the fungus produces fruiting bodies swollen with proteins essential for the ants' growth. The ants have evolved special enzymes to easily digest this superfood and cannot eat anything else. Unable to survive without each other, the symbiotic leafcutters and their fungi nonetheless form the largest colonies of any of the fungus-farming ants. They work together as the dominant herbivores in Neotropical forests.

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Studying Mouse Lemur Genetics Reveals Ancient Forest Mosaic Environment

Today, Madagascar is home to a mosaic of different habitats--a lush rainforest in the east and a dry deciduous forest in the west, separated by largely open highlands. But the island off the southeast coast of Africa hasn't always been like that--a new study published in the Proceedings of the National Academy of Sciences announces that these two ecologically different portions of the island were once linked by a patchwork of forested areas. And to figure it out, the scientists analyzed the DNA of some of the cutest animals on earth--mouse lemurs.

"For a long time, scientists weren't sure how or why Madagascar's biogeography changed in very recent geological time, specifically at the key period around when humans arrived on the island a few thousand years ago. It has been proposed they heavily impacted the Central Highland forests," says Steve Goodman, MacArthur Field Biologist at The Field Museum in Chicago, who co-authored the study and has been studying Malagasy animals for thirty years. "This study shows the landscape was changing thousands of years before humans arrived."

So scientists wanted to learn about the history of Madagascar's landscape--why study mouse lemurs? The tiny primates are the perfect combination of fast-breeding, hardy, and unique to the island. "They reach reproductive maturity within a year, and that means that a lot of generations are produced very quickly," explains Goodman. "That enables us to see evolution at work faster than we would in an animal that took, say, five years to first reproduce." The lemurs, which are found only on Madagascar, live across much of the island, even forested areas that have been damaged by humans. That means that for scientists studying how the island changed over time, mouse lemurs are a jackpot. "The mouse lemurs are forest dependent--as the forest changes, they change. By studying how mouse lemurs evolved in different areas of the island, we're able to glimpse how the island itself changed and learn whether those changes were caused by humans," says Goodman.

By analyzing DNA from five different mouse lemur species, the scientists were able to tell when the different kinds of lemurs branched out from each other. "We were able to characterize tens of thousands of changes in the genomes of mouse lemurs that are now isolated and form separate species. By analyzing these DNA changes, we were able to understand when the species diverged from each other, and by inference, identify the ecological forces that might have driven them apart," says Anne Yoder, Director of the Duke University Lemur Center and lead author on the paper.

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How Mammals Adapt to the Sea

Though mammals adapted on land, a new study by Maria Chikina and Nathan Clark has shown that during three major independent evolutionary events, a number of mammals harkened back to the sea.

For the manatee, walrus, dolphin, and killer whale, the return to the sea involved many evolutionary trade-offs amongst hundreds of genes: a general loss of the number of sensory genes for smell and taste, new functions for genes forming skin and connective tissue, and genes involved in muscle structure and metabolism.

In a massive undertaking, they used 59 placental mammal genomes to calculate the relative rates of evolution for all branches in 18,049 gene trees. To hone in identifying key genes, they used a new approach: rather than catalog single genetic mutations from genome-wide studies, or look for candidate genes in key pathways, or catalog single amino acid changes at the protein level, they calculated a genome-wide average rate of evolution across all species. Then, they determined whether sea mammals had put the evolutionary gas pedal or brake on compared to the average rate. In the next step, they employed these relative rates to identify those genes that may have independently shifted to higher (or lower) rates for five marine species - bottlenose dolphin, orca, walrus, Weddell seal, and West Indian manatee. "By exploiting the diversity within mammals, we stand to learn much about our own genetics and physiology," said Clark. "Our new approach is poised to reveal the evolutionary adaptations for countless other environments, from the sea, high altitudes, the desert, or even underground."

They identified hundreds of genes that revealed three main evolutionary themes - a burst of adaptation, followed by relaxation, and additional constraint -in response to the marine environment.

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Hair, Feathers & Scales Developed From Common Ancestral Trait

The potential evolutionary link between hairs in mammals, feathers in birds and scales in reptiles has been debated for decades. Today, researchers of the University of Geneva (UNIGE) and the SIB Swiss Institute of Bioinformatics, Switzerland, demonstrate that all these skin appendages are homologous: they share a common ancestry. On the basis of new analyses of embryonic development, the Swiss biologists evidenced molecular and micro-anatomical signatures that are identical between hairs, feathers and scales at their early developmental stages. These new observations, published today in Science Advances, indicate that the three structures evolved from their common reptilian ancestor.

Mammalian hairs and avian feathers develop from a similar primordial structure called a 'placode': a local thickening of the epidermis with columnar cells that reduce their rate of proliferation and express very specific genes. This observation has puzzled evolutionary and developmental biologists for many years because birds and mammals are not sister groups: they evolved from different reptilian lineages. According to previous studies, reptiles' scales however do not develop from an anatomical placode. This would imply that birds and mammals have independently 'invented' placodes during their evolution.

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How Plants Conquered the Land 500 Million Years Ago

Research at the University of Leeds has identified a key gene that assisted the transition of plants from water to the land around 500 million years ago.

The ANR gene is required to tolerate 'extreme dehydration' in the moss Physcomitrella patens, a land plant that is used as an experimental model.

Researchers at the Centre for Plant Sciences at the University found that the ANR gene - present in the most ancient land plants - was inherited from ancestral fresh water algae.

The ANR gene has since been lost in the evolution of seed plants. The results are published today in the American Society of Plant Biology's journal The Plant Cell.

Dr Andrew Cuming, who led the research, said: "This gene hadn't been identified so far because most research until now has focused on modern flowering plants.

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North and South American Pleistocene Quaternary Bears Evolved Giantism Independently

The work of University of Adelaide researchers is shedding new light on the evolution of what are believed to be the largest bears that ever walked the Earth.

Dr Kieren Mitchell, from the University's Australian Centre for Ancient DNA, School of Biological Sciences, has a new paper just published in Biology Letters.

He writes: "During the Pleistocene (2.5 million years ago - 11 thousand years ago) giant bears weighing over 1,000kg roamed both North and South America. These giants belonged to a now practically extinct subfamily of bears - Tremarctinae - which is today only represented by the small, herbivorous Andean spectacled bear (Tremarctos ornatus).

"The giant North American bears (Arctodus) and South American bears (Arctotherium) have long been believed to be each others' closest relative. However, by comparing ancient DNA data obtained from representatives of the two extinct genera and comparing them with the living species, we were able to show that Arctotherium is most closely related to Tremarctos and not Arctodus.

"The implication of this result is that these bears represent a remarkable instance of convergent evolution, as giant bears appear to have evolved independently in both North and South America.

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Most Native American Genetic Lineages Were Wiped out During European Colonization

The first largescale study of ancient DNA from early American people has confirmed the devastating impact of European colonisation on the Indigenous American populations of the time.

Led by the University of Adelaide's Australian Centre for Ancient DNA (ACAD), the researchers have reconstructed a genetic history of Indigenous American populations by looking directly into the DNA of 92 pre-Columbian mummies and skeletons, between 500 and 8600 years old.

Published today in Science Advances, the study reveals a striking absence of the pre-Columbian genetic lineages in modern Indigenous Americans; showing extinction of these lineages with the arrival of the Spaniards.

"Surprisingly, none of the genetic lineages we found in almost 100 ancient humans were present, or showed evidence of descendants, in today's Indigenous populations," says joint lead author Dr Bastien Llamas, Senior Research Associate with ACAD. "This separation appears to have been established as early as 9000 years ago and was completely unexpected, so we examined many demographic scenarios to try and explain the pattern."

"The only scenario that fit our observations was that shortly after the initial colonisation, populations were established that subsequently stayed geographically isolated from one another, and that a major portion of these populations later became extinct following European contact. This closely matches the historical reports of a major demographic collapse immediately after the Spaniards arrived in the late 1400s."

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I Smell a Coming Academic Bun Fight: Sima de los Huesos Hominins Really Were Early Neandertals

Previous analyses of the hominins from Sima de los Huesos in 2013 showed that their maternally inherited mitochondrial DNA was distantly related to Denisovans, extinct relatives of Neandertals in Asia. This was unexpected since their skeletal remains carry Neandertal-derived features. Researchers of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, have since worked on sequencing nuclear DNA from fossils from the cave, a challenging task as the extremely old DNA is degraded to very short fragments. The results now show that the Sima de los Huesos hominins were indeed early Neandertals. Neandertals may have acquired different mitochondrial genomes later, perhaps as the result of gene flow from Africa.

Until now it has been unclear how the 28 400,000-year-old individuals found at the Sima de los Huesos ("pit of bones") site in Northern Spain were related to Neandertals and Denisovans who lived until about 40,000 years ago. A previous report based on analyses of mitochondrial DNA from one of the specimens suggested a distant relationship to Denisovans, which is in contrast to other archaeological evidence, including morphological features that the Sima de los Huesos hominins shared with Neandertals.

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