earth's history on a football field

WATCH: Bacteria Invade Antibiotics And Transform Into Superbugs

The Evolution of Bacteria on a "Mega-Plate" Petri Dish from Harvard Medical School on Vimeo.

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If you've ever wanted to watch a superbug evolve before your very eyes, you're in luck. Researchers filmed an experiment that created bacteria a thousand times more drug-resistant than their ancestors. In the time-lapse video, a white bacterial colony creeps across an enormous black petri dish plated with vertical bands of successively higher doses of antibiotic.

The colony pauses when it hits the first band of antibiotic, creating a stark border between the white colony and the black petri dish. Then the bacteria start to edge their way into the toxic soup. More dots appear and they start growing, racing to the next, stronger band of antibiotic. The bacteria are evolving. After almost two weeks of real time have passed, they've become resistant to the strongest antibiotic and completely taken over the kitchen-table-sized petri dish.

We know dangerous bacteria are getting stronger all the time and that it's our fault because of our excessive and indiscriminate use of antibiotics. Each year, 23,000 people in the U.S. die as a result of superbug infections. But we typically don't get to see superbugs created.

For most people, evolution is just conceptual, says Tami Lieberman, an evolutionary microbiologist at MIT. She and her Ph.D. adviser, Roy Kishony at Harvard Medical School, wanted something that would make the evolution of superbugs seem more concrete. "The goal was to see evolution, not to abstract it," she says.

Their video and report were published Thursday in the journal Science.

Look, Ma! No Mitochondria

Scientists have found a microbe that does something textbooks say is impossible: It's a complex cell that survives without mitochondria.

Mitochondria are the powerhouses inside eukaryotic cells, the type of complicated cell that makes up people, other critters and plants and fungi. All eukaryotic cells contain a nucleus and little organelles — and one of the most famous was the mitochondrion.

"They were considered to be absolutely indispensable components of the eukaryotic cell and the hallmark of the eukaryotic cell," says Anna Karnkowska, a researcher in evolutionary biology at the University of British Columbia in Vancouver. Karnkowska and her colleagues describe their new find in a study published online Thursday in the journal Current Biology.

Mitochondria have their own DNA, and scientists believe they were once free-living bacteria that got engulfed by primitive, ancient cells that were evolving to become the complex life forms we know and love today.

For decades, researchers have tried to find eukaryotic cells that don't have mitochondria — and for a while they thought they'd found some. One example is Giardia, a human gut parasite that causes diarrhea. It was considered to be a kind of living fossil because it had a nucleus but didn't seem to have acquired mitochondria. But additional studies on Giardia and other microbes showed that actually, the mitochondria were there.

"It turned out that all of them actually had some kind of remnant mitochondrion," says Karnkowska, who notes that mitochondria perform key jobs in the cell beyond just generating power.

A biggie is assembling iron-sulfur clusters for certain proteins, which is thought to be a mitochondrial function that's really essential. So even if a microbe powers itself in a different way and has a limited form of the organelle that isn't the same as the mitochondria found in people, Karnkowska says, "it's still a mitochondrion and it has some important function for the cell."

That kind of vestigial mitochondrion is what she expected to find when she was a researcher at Charles University in Prague and started investigating a particular gut microbe that had been isolated from a researcher's pet chinchilla.

After she and her colleagues sequenced the gut microbe's genome, however, they found no trace that it made any mitochondrial proteins at all. "So that's a great surprise for us," she says. "That should theoretically kill the cell — it shouldn't exist."

What they learned is that instead of relying on mitochondria to assemble iron-sulfur clusters, these cells use a different kind of machinery. And it looks like they acquired it from bacteria.

The researchers say this is the first example of any eukaryote that completely lacks mitochondria.

Michael Gray, a biochemist at Dalhousie University in Halifax, Nova Scotia, says the researchers have made a "compelling" case that they have a bona fide eukaryote without any vestige of a mitochondrion; he calls the finding "unprecedented."

"The observation is significant, in that it clearly demonstrates that a eukaryote can still be a eukaryote without having a mitochondrion," he tells Shots via email.

However, the results do not negate the idea that the acquisition of a mitochondrion was an important and perhaps defining event in the evolution of eukaryotic cells, he adds.

That's because it seems clear that this organism's ancestors had mitochondria that were then lost after the cells acquired their non-mitochondrial system for making iron-sulfur clusters.

"This is not the missing link of eukaryotic evolution," agrees Mark Van Der Giezen, a researcher in evolutionary biochemistry at the University of Exeter in the United Kingdom.

Still, he says, it is an example of how flexible life is.

"It lives in an area without oxygen and therefore can get rid of a lot of biochemistry that you and I would need in our cells to survive," says Van Der Giezen. "This organism managed to adapt in such a way that it could lose an organelle, which every textbook will tell you is an essential feature of eukaryotes. That's pretty amazing. It shows you that life is extremely creative in finding a way to eke out an existence." npr

CAROTENOID PIGMENTS MAKE EXTINCT DUCK A RARE BIRD INDEED

The pink-headed duck was no lucky duck. In 1948 a single specimen of this waterfowl,Rhodonessa caryophyllacea, was donated to the Division of Birds of the Smithsonian’s National Museum of Natural History. The following year was the last time anyone spotted one of its species—which lived in Bangladesh, Nepal, India and Myanmar—alive.

Now, despite that it is likely extinct, new research has revealed this bird was a rare duck indeed. By shining lasers on the pink head feathers of the lone Smithsonian specimen and analyzing the spectral wavelengths of reflected light, Daniel Thomas of Massey University, New Zealand, and Smithsonian ornithologist Helen James determined it is one of only two species of waterfowl known to incorporate carotenoid pigments in its plumage. Carotenoids are of special interest to scientists because the evolutionary history of their appearance in bird plumage is unresolved. A paper on their study was published recently in the journal The Auk: Ornithological Advances, with Thomas as principle author.

Carotenoid pigments originate in what a bird eats and many of the most vibrant feather colors (red, orange, yellow) are the result of carotenoids, James explains. “Some come straight into the plumage from the diet unmodified and some are modified physiologically by the bird before they go into the plumage.” Flamingoes, for example, get their pink color from the carotenoid pigments in the brine shrimp and blue-green algae they eat.

“There are about 40 types of molecules classed as carotenoid pigments that have been found in bird plumage, they are very common in the songbirds, but until recently it had been thought there were none in waterfowl—ducks, swans and geese,” James adds. “Most visible colors in waterfowl plumage are a combination of melanin pigments, which are not ingested, and structural colors, which are not a pigment but just the structure of the feather.”

In 2014 James and Thomas discovered carotenoid pigments, for the first time, in the plumage of a duck: Australia’s pink-eared duck (Malacorhynchus membranaceus). This bird has tiny pink ‘ear’ spots on each side of its head. “So, we were curious about the pink-headed duck,” James says.

The two scientists then used Raman spectroscopy to study the pigments in the pink-headed duck’s feathers because it is a process that would not damage the Smithsonian’s lone specimen. Traditional methods for identifying pigments in feathers require plucking some feathers and destroying them. During the study Raman spectra were collected from the feathers of 20 other bird species in the Natural History Museum collections to provide a comparative dataset for studying the carotenoids found in the pink-eared and pink-headed duck. Raman analysis of both pink-headed and pink-eared duck plumage suggests that the pink plumage of both birds may be colored with the same type of carotenoid pigment.

“Yet these two ducks are not close evolutionary relatives within the family tree of ducks, waterfowl and geese,” James points out. An inflated balloon-shaped bony structure or bulla in the trachea of male pink-headed ducks has fenestrae or little windows in it—a type that is only found sea ducks and diving ducks, James says. The pink-eared duck is more closely related to stiff tailed ducks. “So it appears the deposition of carotenoids into their plumage was a step that arose separately in each species.”

This coincidence has James pondering a deeper evolutionary question, she says. “Is there a metabolic pathway for putting a carotenoid from the bloodstream into a developing feather that was just turned on or turned off and it happened to be only turned on in these two species of modern Anseriformes [ducks, geese and swans]? This is not a question we can answer. It is one that interests us though.”

Just what the pink-headed duck had in its diet that contained the carotenoid pigments that made its head pink is also a question no one can answer. “Almost nothing is known about what they ate. We really have so little information.” As the duck now appears to be extinct this question may never be known. smithsonianscience.si.edu

Our Parasites And Vermin Reveal Secrets Of Human History

They look like tiny tubes with stumpy legs. They can nestle snugly into pores, right at the base of small hairs. And there are probably hundreds on your face.

The harmless mite Demodex folliculorum, seen here in an electron microscope image, lives in the follicles of eyelashes.

We're taking about Demodex folliculorum, the mite that calls your hair follicles home. "Probably if you've ever gotten a gross gunky plug out of a nose pore, that's what it looks like," says Michelle Trautwein, an evolutionary biologist at the California Academy of Sciences. "When you get to know them, they're actually pretty adorable."

Trautwein and her colleagues have peeled the mites off microscope slides that they super-glued to their faces. They've scraped the little guys off people's foreheads with the curved end of a bobby pin. They've even ferreted out the insects' DNA from tiny spatulas of face grease." They've probably been with us since the origin of our species," she says.

And Trautwein thinks the mites could help answer questions about human migrations through history, perhaps more than genetics or archaeology could alone because of how they're shared among humans.

The mites are the latest in a not-so-regal lineage of parasites and vermin that could help pin down how human ancestors behaved and moved across the continents. When archaeological evidence is scant or human genetic data is too messy, sometimes these millennia-old frenemies — from rats to tapeworms — are the next best option.

"You don't share them with strangers when you give them a hug hello," she says of the mites. They're mostly shared between sexual partners and members of the same nuclear family. Because of that tight bond, the mites can be a pretty good measure of where people came from.

In an exploratory study published this month in Proceedings of the National Academy of Sciences, the researchers collected mites from the faces of about 70 people with different origins, most of them living in the U.S., and sequenced the mites' mitochondrial DNA. They found that people from different continents harbor different varieties of mites on their faces. Even generations after a family leaves one geographic region for another, Trautwein and her colleagues found, their descendants can retain those original mite populations. Think of them as family heirlooms.

"Basically, as all humans evolved in Africa our mites evolved with us," says Trautwein. "And as populations became isolated they evolved into their own lineages, just like humans did."

"They are potentially gross and they do infect us and take things from us, but to understand ourselves, it's a really great potential tool to use," says George Perry, an anthropologist and biologist at Pennsylvania State University who was not involved with the study. "It's an amazing, largely untapped area to learn about our own history."

Perry's group is researching how tapeworms, which live in the intestines of mammals, could help show when hominins — human ancestors and their relatives — started consistently eating meat. The archaeological evidence is pretty meager — just a few scratched up animal bones from a couple of million years ago. It's assumed that human ancestors first got tapeworms when they domesticated pigs and cows sometime in the last 12,000 years and started routinely eating undercooked meat, which is how the worms would transfer over.

But, he says, the three species of tapeworm that currently inhabit humans are actually most similar to those of lions and hyenas. Perry says the similarity suggests that hominins picked them up long before the domestication of herbivores, when they were consistently chowing down on the same animals as lions and hyenas. He's now studying tapeworm adaptations to heat stress to see if it yields hints about when humans started cooking meat.

Rodents also have been useful tools in piecing together human travel routes. Rats helped corroborate the hypothesis that indigenous Taiwanese people first colonized Polynesia about 3,000 years ago. There isn't much evidence left of the first generations of people to colonize New Zealand, but there is archaeological evidence of a rat population that arrived on the island and was well established by about 700 years ago. That suggests that humans brought them there on their boats.

Lice might take the cake when it comes to vermin that have revealed the most snippets of human history. Scientists have used louse DNA to determine when human ancestors lost their fur and started wearing clothes. Human ancestors picked up pubic lice from gorilla ancestors some 4 million years ago, meaning that by that point the islands of head hair and pubic hair were far enough apart to provide two different environments for their parasite guests. This change suggests to anthropologists that our modern way of regulating body temperature may have come about early in our evolutionary history. (It also suggests some unexpected cavorting between gorilla and human ancestors.)

DNA analysis showed that body lice diverged genetically from head lice somewhere between 30,000 and 114,000 years ago, giving archaeologists a minimum date for when people first started wearing clothes. Before clothes, there wouldn't have been an environment separate enough for a group of lice to inhabit and evolve separately from the ones on people's heads.

"We're really just a habitat for all sorts of natural life," says Trautwein. "People think that evolution and wildlife are these remote things, but it's happening all over us."

If it weren't, pieces of deep human history might still be hidden. npr

South African Cave Yields Strange Bones Of Early Human-Like Species

Scientists have discovered the fossilized remains of an unusual human-like creature that lived long ago. Exactly how long ago is still a mystery — and that's not the only mystery surrounding this newfound species.

The bones have a strange mix of primitive and modern features, and were found in an even stranger place — an almost inaccessible chamber deep inside a South African cave called Rising Star.

"It is perhaps one of the best known caves in all of South Africa," says Lee Berger, who studies human evolution at the University of the Witwatersrand, Johannesburg.

In 2013, some local cavers found some fossils inside Rising Star cave. Berger had asked them to be on the lookout, so they brought him photos.

"And there I saw something I perhaps thought I'd never see in my life," recalls Berger. "That is, clearly primitive hominin remains lying on the floor of a cave."

A jaw and a skull were just sitting there in the dirt — usually such bones are encased in rock.

Berger was excited, but he knew he personally could never reach this fossil site. To get into the cave chamber, you have to climb a steep, jagged rockfall called Dragon's Back, then wiggle through a small opening that leads to a long, narrow crack.

The crack is only about 7 ½ inches wide, and goes down more than 30 feet. Squeezing through it is the only way to reach the chamber of bones at the bottom.

Since he couldn't go, Berger sent in his tall, skinny 16-year-old son. "When he came out after 45 minutes, he stuck his head out. And to tell you how bad I am, I didn't say: 'Are you OK?' I said: 'And?' And he says, 'Daddy, it's wonderful.' "

Berger got funding from the National Geographic Society to excavate the site. And he advertised for research assistants on Facebook — for skinny scientists who weren't claustrophobic. Six women took the job.

They worked in the chamber almost like spacewalkers, communicating with researchers outside, via cameras and about 2 miles of fiber optic cable. The team in the chamber used paintbrushes and toothpicks to gently unearth fossil bones — there were more than 1,550 of them, an incredible treasure trove. The researchers describe their find Thursday in a journal called eLife.

"Often I was wondering, 'How on Earth are we going to get that fossil out?' because the density of bones in that chamber was so great, it was like a puzzle to get each fossil out," says Becca Peixotto, one of the scientist-cavers and a doctoral student in anthropology at American University.

The bones come from at least 15 individuals, says John Hawks, a paleoanthropologist from the University of Wisconsin-Madison, who was on the team that studied the bones.

"We have every age group represented" among the fossils, he says. "We have newborns; we have children of almost every age; we have adults and old adults."

He says these creatures were short — less than 5 feet tall — and thin. They have a particular combination of features that has never been seen before. "It's a new species to science," says Hawks. Researchers have named it Homo naledi, because "naledi" means "star" in a local South African language.

"They have a very small brain. They are not human-like at all in their brain," Hawks says. "It's around a third the size of a human brain today."

But the creatures had feet like us, and walked in a very human-like way. Their hands were also like ours, but their fingers were more curved.

The researchers also tackled this question: How did these human-like creatures get into such a crazy spot? It looks as though the cave chamber has always been hard to reach.

There are no animal bones there, except for a handful of bits from birds and mice. There's no evidence that a carnivore dragged the human-like creatures in, or that they somehow got washed in. And there's no evidence of a mass death, such as a cave accident.
Berger believes someone had to have put the bodies there.

"Homo naledi was deliberately disposing of its dead in a repeated, ritualized fashion in this deep underground chamber," he says.

That's quite a claim — that kind of ritual has been thought to be unique to modern humans or our very close relatives.

And really, the whole discovery — from the bones to their bizarre location — has perplexed experts on human evolution.

"To be honest, I would really distrust anyone who thinks they understand what the significance of these finds is," says Bernard Wood, a paleoanthropologist at George Washington University.

Usually scientists can tell how old fossilized bones are, but in this case the geology of the cave gives no clues. The bones could be less than 100,000 years old or several million years old.

"These folks do not have an age, yet they have some remarkable fossils, and the context of them is also remarkable," says Wood. "It's not only remarkable, it's also rather weird. But nonetheless, the fossils are important. So the community is, I think, struggling to work out what it all means."

He notes that only a small section of the cave chamber has been excavated, and it looks like many more bones are down there.

"There is the potential for thousands of specimens in that cave," says Wood. "Intellectually, it's a real puzzle. And I think it's going to take scientists quite a time to get their heads around what the real significance of these discoveries is." npr

Fossil Specimen Reveals a New Species of Ancient River Dolphin

Smithsonian scientists and colleagues have discovered a new genus and species of river dolphin that has long been extinct. They made the discovery after carefully examining fossil fragments from Panama. The fossil fragments also shed new light on the evolution of today’s freshwater river dolphin species. The team’s research was published Sept. 1 in the scientific journal Peer J.

The fossil, which dates from 5.8–6.1 million years ago, was found on the Caribbean coast near the town of Piña, Panama. It consists of half a skull, lower jaw with an almost entire set of conical teeth, right shoulder blade and two small bones from the dolphin’s flipper. In comparison with other river dolphins—both fossil and living—the shape and size of these parts suggests that the full specimen may have been more than 9 feet long.

Today there are only four species of river dolphins―all living in freshwater or coastal ecosystems and all endangered, including the Yangtze river dolphin, which is likely now extinct. Each of the modern river dolphin species show a common solution to the problem of adapting away from marine to freshwater habitats by converging upon a body plan that includes broad, paddle-like flippers, flexible necks and heads with particularly long, narrow snouts—all the better to navigate and hunt in winding, silty rivers.

But fossil evidence suggests that river dolphins’ ancestors were widespread around the globe. I. panamensis was clearly one of them, and its fossil remains have helped the team understand something less clear: When in their evolutionary tract did river dolphins transition from the saltwater of the ocean to the freshwater of rivers?

“We discovered this new fossil in marine rocks, and many of the features of its skull and jaws point to it having been a marine inhabitant, like modern oceanic dolphins,” said the study’s lead author Nicholas D. Pyenson, curator of fossil marine mammals at the Smithsonian’s National Museum of Natural History. “Many other iconic freshwater species in the Amazon, such as manatees, turtles and stingrays have marine ancestors, but until now, the fossil record of river dolphins in this basin has not revealed much about their marine ancestry. Isthminia now gives us a clear boundary in geologic time for understanding when this lineage invaded Amazonia.”

Other fossilized animals found at the same site as I. panamensis were marine species, indicating that unlike river dolphins living today, I. panamensis lived in the salty waters of a food-rich Caribbean Sea, before the full closure of the Panama Isthmus.

“Isthminia is actually the closest relative of the living Amazon river dolphin,” said study co-author Aaron O’Dea, staff scientist at the Smithsonian Tropical Research Institute in Panama. “While whales and dolphins long ago evolved from terrestrial ancestors to fully marine mammals, river dolphins represent a reverse movement by returning inland to freshwater ecosystems. As such, fossil specimens may tell stories not just of the evolution these aquatic animals, but also of the changing geographies and ecosystems of the past.”

The Smithsonian’s Digitization Program Office collaborated with the scientific team to create a high-resolution 3-D scan of the fossil, allowing the scientists to create 3-D prints of the delicate specimen, whose bones are too fragile to be molded and casted by traditional approaches. A 3-D print of the fossil is on permanent display at Panama’s BioMuseo—the original specimen will remain in the Smithsonian’s collection at the National Museum of Natural History. The public can also explore and download high resolution scans of the dolphin’s skull, jaw and shoulder blade at the Smithsonian X 3-D website 3D.SI.EDU.

The fossil was discovered by Dioselina Vigil, then a STRI intern and student at the University of Panama. The name of the new genus, Isthminia, recognizes both the Panama Isthmus and the fossil specimen’s living relative, the Amazon river dolphin, Inia geoffrensis. The study’s authors chose the species name, panamensis, to recognize the Republic of Panama, its people, and the many generations of scientists who have studied its geological and biological histories. smithsonianscience.si.edu

Evolution isn't controversial for scientific reasons, but it is controversial, in part, for psychological reasons

The theory of evolution by natural selection is among the best established in science, yet also among the most controversial for subsets of the American public.

For decades we've known that beliefs about evolution are well-predicted by demographic factors, such as religious upbringing and political affiliation. There's also enormous variation in the acceptance of evolution across different countries, all of which suggests an important role for cultural input in driving beliefs about evolution. A child raised by Buddhists in California is much more likely to accept evolution than one raised by evangelical protestants in Kansas.

But in the last 20 years or so, research in psychology and the cognitive science of religion has increasingly focused on another factor that contributes to evolutionary disbelief: the very cognitive mechanisms underlying human cognition.

Researchers have argued that a variety of basic human tendencies conspire to make natural selection especially aversive and difficult to understand, and to make creationism a compelling alternative. For instance, people tend to prefer explanations that offer certainty and a sense of purpose when it comes to their lives and the design of the natural world and they have an easier time wrapping their heads around theories that involve biological categories with clear boundaries — all of which are challenged by natural selection.

These factors are typically taken to hold for all humans, not only those who reject evolution. But this naturally raises a question about what differentiates those individuals who do accept evolution from those who do not. In other words, if the California Buddhist and the Kansas protestant share the same cognitive mechanisms, what accounts for their differing views on evolution?

In fact, there's evidence that individuals vary in the extent to which they favor purpose and exhibit other relevant cognitive tendencies, and that this variation is related to religious belief — itself a strong predictor of evolutionary belief. But there's a lot we don't know about how differences between individuals drive different beliefs about evolution, and about how these individual differences interact with cultural input.

A new paper by psychologist Will Gervais, just published in the journalCognition, sheds new light on these questions. In two surveys conducted with hundreds of undergraduates attending a large university in Kentucky, Gervais found an association between cognitive style and beliefs about evolution. Gervais used a common task to measure the extent to which people engage in a more intuitive cognitive style, which involves going with immediate, intuitive judgments, versus a more analytic cognitive style, which involves more explicit deliberation, and which can often override an intuitive response. npr

Evolution of whale tails. Follow the whale. 1956

Kennewick Man

New genetic evidence suggests that Kennewick Man, an 8,500-year-old skeleton found in Washington state, is related to members of a nearby Native American tribe.

"We can see very clearly that Kennewick Man is more closely related to present day Native Americans than he is to anybody else," says Eske Willerslev from the University of Copenhagen. He specializes in the study of ancient DNA and led the research.

Willerslev's team extracted DNA from one of the skeleton's hand bones. They compared it to DNA from various groups around the world, including Native Americans from North and South America.

They found that Kennewick Man is not related to the Ainu of Japan or Polynesians. But he does share a close genetic affinity with members of the Confederated Tribes of the Colville Reservation. These tribes stem from the Pacific Northwest, and are among several Native American groups that demanded custody of the skeleton.

These results were published Thursday in the scientific journal Nature.

But if that sounds like "case closed," it isn't.

Willerslev acknowledges that there is very little genetic information about modern Native Americans to make comparisons. There might be other tribes more closely related to Kennewick Man. And it also could be that Native Americans are descendants of some relative of Kennewick Man who lived 10,000 to 15,000 years ago.

"We probably will never be able to say who is, in fact, the closest living relative of Kennewick Man," Willerslev says.

And there's at least one scientist who isn't convinced by the genetic evidence. Physical anthropologist Douglas Owsley of the Smithsonian Institution has edited a 700-page study of the skeleton.

Owsley can read the bones like we might read a book. He looks for ridge lines that indicate which muscles Kennewick Man used the most, and what he was doing with them. First off? He had muscular legs like a soccer player — likely from running, trudging and hunting.

"In his leg structure, he's certainly accustomed to very rapid movement, quick movement, and you can read that in those muscle ridges," says Owsley.

He also likely had killer arms from throwing a tricky kind of spear. Owsley says Kennewick Man was so strong in his right arm, he was like a pro baseball pitcher, and the bones show he got today's equivalent of a career-ending sports injury.

"If it happened to a contemporary baseball pitcher, they'd need surgery," says Owsley. The injury, he says, "took off a piece of bone off the back side of the shoulder joint."

Owsley says Kennewick Man stood about 5 feet 7 inches tall and weighed about 170 pounds. And he wasn't any stranger to pain. K-Man, as he's known in eastern Washington, got hit on the head a few times and was stabbed with a basalt rock point that got stuck in his hip.

Owsley's research includes these big revelations about the Paleoamerican's origins. For one, Kennewick Man lived on the coast, not inland along the Columbia River where his bones were found. The scientists can tell from tiny bits of his bones and the enamel on his teeth that he ate mostly marine animals, like seals.

At his laboratory, he displays a cast of Kennewick Man's skull — alongside skulls of three Native Americans. Clearly, Kennewick Man does look different.

"It is a much narrower and longer — relatively longer — cranium, and the way the base of the cranium is configured," he says. "It is different from what we see in Native Americans."

Owsley doesn't dispute that Kennewick Man, or his people, passed on genes that now show up in Native American populations. But he doesn't think the evidence is sufficient to satisfy the repatriation law that requires Native American remains to be turned over to tribal authorities. npr 2

DNA evidence suggests that the split between dogs and their wild ancestors occurred closer to 30,000 years ago

It looks like dogs might well have been man's (and woman's) best friend for a lot longer than once thought.

The long-held conventional wisdom is that canis lupus familiaris split from wolves 11,000 to 16,000 years ago and that the divergence was helped along by Stone Age humans who wanted a fellow hunter, a sentry and a companion.

Now, DNA evidence suggests that the split between dogs and their wild ancestors occurred closer to 30,000 years ago.

Publishing in Thursday's edition of Current Biology, the authors of a new study looked at the genome of a 35,000-year-old wolf from the Taimyr Peninsula in northern Siberia. "We find that this individual belonged to a population that diverged from the common ancestor of present-day wolves and dogs very close in time to the appearance of the domestic dog lineage," they wrote in the abstract.

The team, led by Pontus Skoglun, a research fellow at Harvard, concluded that the mutation rate for canines is "substantially slower than assumed by most previous studies, suggesting that the ancestors of dogs were separated from present-day wolves before the Last Glacial Maximum."

In other words, there may have been a faithful Fido walking with a human before the end of the last Ice Age (and before agriculture).

As The New York Times writes: "Based on the differences between the genome of the new species, called the Taimyr wolf, and the genomes of modern wolves and dogs, the researchers built a family tree that shows wolves and dogs splitting much earlier than the 11,000 to 16,000 years ago that a study in 2014 concluded."

However, a study reported in 2013 places the date of the canine split closer to the study published on Thursday. As NPR's Nell Greenfieldboyce reported then, a team headed by Robert Wayne, a biologist at the University of California, Los Angeles, and publishing in Science, used DNA analysis to peg the date at somewhere between 18,800 to 32,100 years ago.

In the new study, an author of the report was quoted by the Times as saying the simplest explanation for the new data is that dogs were domesticated as much as 30,000 years ago, but he cautions that the study does not prove it. "We can't just look at the DNA and say whether a canid was living with modern humans," he was quoted by the newspaper as saying.

"One scenario is that wolves started following humans around and domesticated themselves," Dalen told BBC. "Another is that early humans simply caught wolf cubs and kept them as pets and this gradually led to these wild wolves being domesticated. If this model is correct then dogs were domesticated by hunter gatherers that led a fairly nomadic lifestyle." npr

Earth's First Snake Likely Evolved On Land, Not In Water

Some scientists have speculated that snakes first evolved in water and that their long, slithery bodies were streamlined for swimming. But a new analysis suggests that the most recent common ancestor of all snakes actually lived on land.

This ancestral protosnake probably was a nocturnal hunter that slithered across the forest floor about 120 million years ago. And it likely had tiny hind limbs, left over from an even earlier ancestor, says Allison Hsiang, a researcher at Yale University.

"They probably weren't using them in locomotion in any way, but they did probably still have vestigial hind limbs stuck on the back of their bodies," Hsiang says.

The evolutionary origin of snakes has been a bit of a mystery for scientists, because the fossil record has an unfortunate dearth of snakes. "For a long time there weren't very good snake fossils," says Hsiang, who explains that researchers had not found "things that sort of told us what snakes looked like early on, or transitional fossils between snakes and their closest ancestors."

That's because snakes are mostly small, with fragile skeletons that aren't easily preserved — although there are some notable exceptions, such as Titanoboa, which lived 60 million years ago and could grow longer than 40 feet.

In the past decade, though, scientists have discovered a bunch of new snake fossils — some new species, as well as better-quality specimens of known species. "Previously, we just had, say, a few isolated vertebrae," says Hsiang, "which tells you it's a snake, but doesn't really tell you very much else."

The new fossils allowed Hsiang and some colleagues to do a rigorous, comprehensive analysis, to try to determine what the most recent common ancestor of all snakes might have been like. Besides fossils, the team studied the genes and anatomy of living snakes. "We had a total of 73 species, and I believe 15 of those were fossil species," says Hsiang.

Their analysis, described in the issue of BMC Evolutionary Biology published Tuesday, supports the idea of an early snake that slithered over the ground, and perhaps went into burrows to find food. "Snakes probably did not evolve, originally, to be in water," says Hsiang. "That's not why they developed this body plan; that's not what the earliest snakes were doing."

It looks like the ancestral snake had needle-like hooked teeth that it used to grab small, rodent-like critters, which it then swallowed whole. And it probably wouldn't have been able to eat anything much bigger than its own head. npr