• Dogs and humans evolved together, study suggests

    Gary Kramer / U.S. Fish and Wildlife Service

    The gray wolf (Canis lupus lycaon), also known as the timber wolf, is the largest wild member of the dog family. Found in parts of North America, gray wolves are making a comeback in the Great Lakes, northern Rockies and Southwestern United States.

    By Tia Ghose LiveScience

    Dogs are more than man's best friend: They may be partners in humans' evolutionary journey, according to a new study.

    The study shows that dogs split from gray wolves about 32,000 years ago, and that since then, domestic dogs' brains and digestive organs have evolved in ways very similar to the brains and organs of humans.

    The findings suggest a more ancient origin for dog domestication than previously suggested. They also hint that a common environment drove both dog and human evolution for thousands of years.

    "As domestication is often associated with large increases in population density and crowded living conditions, these 'unfavorable' environments might be the selective pressure that drove the rewiring of both species," the researchers wrote in their article, published Tuesday in the journal Nature Communications.

    First domestication
    It isn't clear precisely when wolves were tamed and transformed into man's best friend, and the date has been hotly debated. An ancient, doglike skull uncovered in the Siberian Mountains suggested that the first dogs were domesticated around 33,000 years ago from gray wolves. But genetic analysis suggested dogs in China were domesticated only about 16,000 years ago.

    In any case, most researchers agree that by about 10,000 years ago, dogs were firmly ensconced in human society. [10 Breeds: What Your Dog Says About You]

    Some studies show that the wild dogs of South China may have been the first domesticated canines.

    To understand this domestication, Guo-dong Wang, a genetics researcher at the Chinese Academy of Sciences, and his colleagues analyzed the DNA of four gray wolves, three indigenous Chinese dogs and a German shepherd, a Belgian Malinois and a Tibetan mastiff.

    The DNA suggests that the gray wolves split off from the indigenous dogs about 32,000 years ago, the researchers said.

    "Chinese indigenous dogs might represent the missing link in dog domestication," the researchers write in the paper.

    Since then, dogs' evolution has been gradual, and there were no sharp decreases in the dog population over time, suggesting dogs gradually became domesticated, after many years of scavenging from humans.

    Parallel evolution
    The team then compared corresponding genes in dogs and humans. They found both species underwent similar changes in genes responsible for digestion and metabolism, such as genes that code for cholesterol transport. Those changes could be due to a dramatic change in the proportion of animal versus plant-based foods that occurred in both at around the same time, the researchers said.

    The team also found co-evolution in several brain processes — for instance, in genes that affect the processing of the brain chemical serotonin. In humans, variations in these genes affect levels of aggression. (This shared genetic trajectory might explain why Fluffy can be helped by antidepressant drugs, the authors hypothesize.)

    Follow Tia Ghose on Twitter and Google+. Follow LiveScience @livescience, Facebook and Google+. Original article on LiveScience.com.

    Copyright 2013 LiveScience, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

  • Genome of ancient-looking fish gives clues to first limbed landlubbers

    Aquamarine Fukushima

    An African coelacanth, photographed using a Remotely Operated Vehicle off the coast of Tanga, Tanzania.

    By John Roach, Contributing Writer, NBC News

    The genome of the coelacanth, an ancient-looking lobed-finned fish, has been sequenced and is already providing insight to the evolutionary changes that allowed the first four-limbed animals, called tetrapods, to crawl out of the water and on to land.

    The sequence and preliminary analysis, reported Thursday in the journal Nature by a team spanning 40 research institutions and 12 countries, is a "massive piece of work," Xiaobo Xu, a paleontologist at Kean University who was not involved in the effort, told NBC News in an email.

    "The paper really provides rare and valuable genomic data for offering heavy-weight opinions on issues bearing on the fish (to) tetrapod transition," he said.

    It also settles a debate that has long raged amongst evolutionary biologists: what fish is the closest relative of tetrapods: the coelacanth or the equally odd-looking lobed-finned lungfish. The winner, according to analysis of the newly-published genome, is the lungfish.

    "We think we have definitively shown it now," Jessica Alföldi, a research scientist at the Broad Institute of MIT and Harvard and co-first author of the paper, told NBC News. "They are very close, which is why it took so much data to figure it out."

    Slow evolving genes
    Scientists thought coelacanths went extinct about 70 million years ago, during the Late Cretaceous period. That changed when a fish trawler off the South African coast delivered a fresh-caught coelacanth to a local natural history museum in 1938, proving that the fish are alive and well.

    The coelacanths' odd, ancient-looking looks raised eyebrows and earned it the nickname "living fossil" — much to the chagrin of evolutionary biologists, noted Alföldi. ("It makes people think there was no evolution," she explained.)

    Analysis of the coelacanth genome reveals that the ancient fish is indeed evolving just about as quickly as all vertebrates in every aspect except one: its genes, the stretches of protein that code for specific functions.

    Other aspects, such as the amount of transposable elements — so-called "junk DNA" — that jump around the genome, is about the same as other species, a sign of evolution. In addition, big chunks of DNA are constantly being rearranged. 

    "But if we look at the proteins and say how much have these proteins changed in the last 400 million years, they have changed more in us than in the coelacanths, and they have changed a lot more in pretty much every other vertebrate species that we looked at," Alföldi said.

    Why? 

    One speculation is that coelacanths haven't needed to evolve, Alföldi said. They live in deep sea caves and appear to have few predators or competitors for food.

    Fin to limb
    Comparisons of the coelacanth genome with other vertebrates allows researchers to see what genes were lost and regulatory elements gained as lobed-finned fish crawled out of the sea and on to land. 

    Some of the preliminary findings are expected, such as a suite of changes to regions of the genome that control limb development, for example. 

    "This is consistent with the hypothesis that the autopod (the hand and digits) of land-living vertebrates is a modification of features already present in lobe-finned fishes, rather than something that arose entirely de novo," Matt Friedman, a paleobiologist at Oxford University, said in an email to NBC News.

    Others, however, were unexpected, though "end up making total sense once you think about it," Alföldi said.

    For example, genes related to smell exhibit a wide range of changes as vertebrates came on to land, which make sense given that smelling underwater is different than on land, she noted. Other changes are seen in sections of the genome that regulate immunity and the way fish and land animals poop.

    For Friedman, who was not involved with the team, the findings are in line with decades of paleontological and anatomical studies of the coelacanths and other lobe-finned fish.

    "Apart from specific genetic details — which are of course new — most of what is here seems to corroborate our current ideas about evolutionary changes associated with the origin of terrestriality," he said.

    The specific genetic details will allow members of the research team and the broader scientific community to better understand what Yu called "the unique genomic features that shed light on the shared evolutionary past of lobe-finned fish and tetrapods."

    John Roach is a contributing writer to NBC News. To learn more about him, visit his website. 

  • Critters evolve rapidly to cope with environmental change

    Thomas Cameron

    Wild soil mites that were captured and put in a research lab adapted to their new environment within five generations, a new study shows.

    By John Roach, Contributing Writer, NBC News

    Critters can evolve over just a handful of generations to survive whatever environmental maladies humans toss their way, from climate change to over fishing, suggests a new study. 

    "That is the first take-home message, and it is a positive message," Thomas Cameron, a biologist at Umea University in Sweden, told NBC News as he explained his new findings reported Tuesday in the journal Ecology Letters.

    The findings overturn the common assumption that evolution only occurs gradually over hundreds or thousands of years, he said. Rather, it happens quickly and is intertwined with ecological change.

    The research was based on the speed wild-caught soil mites adapted to a life of poking and prodding in a research lab. Within five generations, the wild mites genetically evolved their life-history traits to reverse a downward spiral toward extinction.

    They did this by doubling the amount of time they spent as juveniles. That is, they delayed entry to adulthood.

    "Those mites with the genes selecting for the slowest growth had the highest fecundity and so we see that, in the long term, the reason that the population recovered was that there was selection for increased fecundity, increased number of offspring per individual," Cameron said.

    More offspring translates to a bigger population.

    The delayed maturity adaptation held in populations of mites that had either 40 percent of their juveniles or adults harvested once a week, though the harvested populations changed in other ways as well. 

    For example, in the case of the adult-harvested mites, the populations delayed maturity even longer, since adulthood was akin to a death sentence. And when they reached adulthood, they were bigger than the non-harvested populations and thus able to lay even more eggs.

    Mites are commonly used to study broad biological questions and the findings from the lab have implications for the management of animal populations that humans hunt and fish, noted Cameron. For example, management plans may need to take rapid evolution into account, and even nudge it along.

    Instead of natural selection, think of it as managed selection. In the case of land animals such white-tailed deer, game wardens could select which animals are harvested in order to nudge deer evolution itself in one direction or another. With fish, where population loss has raised concern around the world, such management may not be possible, however.

    "It is certainly not very easy for fisheries to harvest small individuals but leave the big ones," Cameron noted, in one hypothetical scenario for increasing the size of fish in a population. "That's because it's not the way the nets work."

    John Roach is a contributing writer for NBC News. To learn more about him, visit his website. 

  • Brain size didn't drive primate evolution, research suggests

    Erin Conway-Smith / AP file

    Chimpanzees sit in an enclosure at the Chimp Eden rehabilitation center, near Nelspruit, South Africa in this February 2011 photo.

    By Tia Ghose
    LiveScience

    Brain organization, not overall size, may be the key evolutionary difference between primate brains, and the key to what gives humans their smarts, new research suggests.

    In the study, researchers looked at 17 species that span 40 million years of evolutionary time, finding changes in the relative size of specific brain regions, rather than changes in brain size, accounted for three-quarters of brain evolution over that time. The study, published Tuesday in the Proceedings of the Royal Society B, also revealed that massive increases in the brain's prefrontal cortex played a critical role in great ape evolution.

    "For the first time, we can really identify what is so special about great ape brain organization," said study co-author Jeroen Smaers, an evolutionary biologist at the University College London.

    Is bigger better?
    Traditionally, scientists have thought humans' superior intelligence derived mostly from the fact that our brains are three times bigger than our nearest living relatives, chimpanzees.

    But bigger isn't always better. Bigger brains take much more energy to power, so scientists have hypothesized that brain reorganization could be a smarter strategy to evolve mental abilities. [10 Odd Facts About the Brain]

    To see how brain organization evolved throughout primates, Smaers and his colleague Christophe Soligo analyzed post-mortem slices of brains from 17 different primates, then mapped changes in brain size onto an evolutionary tree.

    Over evolutionary time, several key brain regions increased in size relative to other regions. Great apes (especially humans) saw a rise in white matter in the prefrontal cortex, which contributes to social cognition, moral judgments, introspection and goal-directed planning. The white matter carries axons, the wires connecting different brain cells, suggesting that that the great apes' brains were evolving for greater neural connections.

    "The prefrontal cortex is a little bit like the CEO of the brain," Smaers told LiveScience. "It takes information from other brain areas and it synthesizes them."

    When great apes diverged from old-world monkeys about 20 million years ago, brain regions tied to motor planning also increased in relative size. That could have helped them orchestrate the complex movements needed to manipulate tools — possibly to get at different food sources, Smaers said.

    Gibbons and howler monkeys showed a different pattern. Even though their bodies and their brains got smaller over time, the hippocampus, which plays a role in spatial tasks, tended to increase in size in relation to the rest of the brain. That may have allowed these monkeys to be spatially adept and inhabit a more diverse range of environments.

    Prefrontal cortex
    The study shows that specific parts of the brain can selectively scale up to meet the demands of new environments, said Chet Sherwood, an anthropologist at George Washington University, who was not involved in the study.

    The finding also drives home the importance of the prefrontal cortex, he said.

    "It's very suggestive that connectivity of prefrontal cortex has been a particularly strong driving force in ape and human brains," Sherwood told LiveScience.

    Follow Tia Ghose on Twitter @tiaghose. Follow LiveScience @livescience, Facebook and Google+. Original article on LiveScience.com.

    Copyright 2013 LiveScience, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

  • Swallows evolve shorter wings to avoid cars, study suggests

    Current Biology / Brown et al.

    Cliff swallows that build their nests under bridges and overpasses in Nebraska have evolved shorter wings to avoid getting hit by cars, new research suggests.

    By John Roach, Contributing Writer, NBC News

    Cars and trucks thundering down the road in southwestern Nebraska stand a much lower chance today of smacking a cliff swallow than they did in the 1980s, according to a new study that suggests the birds have evolved shorter wings to pivot away from oncoming traffic. 

    The adaptation is important for the birds’ survival given that they nest by the thousands under bridges and overpasses there, noted Charles Brown, a biologist at the University of Tulsa in Oklahoma who regularly drives those same roads to and from a nearby research station.

    "The decline in road kill is very real," he told NBC News. "What’s causing it is more a matter of speculation." 

    He and colleague Mary Bomberger Brown from the University of Nebraska, Lincoln, know for a fact that the bird population overall has shorter wings today than it did when the researchers first started studying it in 1982 and the road-killed birds have longer wings than average.

    Also Read: How do critters survive in the concrete jungle? It takes smarts

    Given that traffic, if anything, has increased over the years, scavengers that eat road-killed birds have not increased, and the bird population itself is much larger than it was when they started their observations, the most likely explanation for the decline has to do with the shorter wings.

    "A shorter wing confers greater maneuverability in flight and so if you are more maneuverable, you can turn more rapidly, you can pivot away from something," Brown explained.

    Current Biology / Brown et al.

    A massive colony of cliff swallows is shown here on an interstate highway bridge in Nebraska.

    He noted that a shorter wing allows swallows to take off in a more vertical than horizontal fashion.

    "If you are sitting on a road and car is coming, it is probably best to fly up as quickly as possible rather than take off flying ahead of the car because you are probably not going to make it," he said. "So, the idea is that the wing length indicates the relative ability of these birds to avoid collisions."

    Nimble flight, Brown added, is also key for swallows to be able to catch their prey — insects that zig-zag. It's possible that the birds evolved shorter wings to better catch insects associated with corn crops. Much of the surrounding prairie has been converted to agriculture in recent decades.

    Evolution, he noted, would favor birds best adapted to catch the available food. Swallows are also known to learn behaviors and it could be that the birds that learned to avoid cars have survived and passed on their genes.

    Whatever the reason, said Brown, the wings have indeed gotten shorter. 

    "I don't think necessarily road mortality is the sole cause of this," he said. "I think there are other factors that may be leading to this, but the point is, I think that for whatever reasons, these animals can adapt very rapidly to these urban environments and they can avoid being killed."

    The findings are reported today in the journal Current Biology. 

    John Roach is a contributing writer for NBC News. To learn more about him, check out his website. 

  • What killed Neanderthals? Scientists blame those rascally rabbits

    Patrick Pleul / EPA

    The inability to catch small prey, such as wild rabbits, may have contributed to Neanderthal extinction.

    By Nidhi Subbaraman

    Neanderthals were big-game hunters who feasted on mammoth and rhino but didn’t or couldn’t eat smaller, leaner meat. Their picky diet — or limited hunting skills — could have made them vulnerable when mammal populations shrank and their favorite dinner became harder to find.

    A broad survey of animal remains recorded at early human and Neanderthal sites across Spain, Portugal and France gives us new insight as to what humans and Neanderthals ate. One trend stuck out to scientists who assembled the data: Rabbit remains became much more popular at human sites just about the time that Neanderthals disappeared, about 30,000 years ago.

     Given how common bunnies would have been in that area, the trend hints that Neanderthals did not adapt their diet to include them. After all, the evidence suggests, early humans seem to have made the switch.

    There’s no data to explain this trend, but there are theories. Neanderthals may have avoided rabbit dinners because they lacked the technology to catch them, says John Stewart, who studies fossil records and ancient climate at Bournemouth University.

    “With modern humans, you see technology that allows them to catch smaller or faster-moving prey,” Stewart told NBC News. That  leads to the “strong possibility” that humans were more efficient than Neanderthals at catching smaller but faster animals. Stewart and his collaborators explain their findings in a paper in the Journal of Human Evolution.

    Of course, Neanderthals didn’t just live in Iberia. And in n other parts of the world, there’s evidence to show that they were catching seals and fish and mussels, and even birds.

    But Stewart believes that the rabbit diet story is an indication of challenges Neanderthals faced all over the world. “I think the rabbit was just a symptom [of their extinction] rather than the cause,” Stewart says. “Neanderthals were more vulnerable because they had less tricks up their sleeve, less breadth of possibilities.”

    More about Neanderthal histories: 

    Via New Scientist

    Nidhi Subbaraman writes about science and technology. Follow on Twitter, Google+. 

  • African-American's Y chromosome sparks shift in evolutionary timetable

    University of Arizona

    A photomicrograph shows an X chromosome at left, alongside a shrunken Y chromosome. The Y chromosome is passed down exclusively from father to son and can serve as an indicator of male-line human diversity.

    By Alan Boyle, Science Editor, NBC News


    Scientists say an African-American male's odd genetic signature suggests that the human Y chromosome's lineage goes back further in time than they thought — perhaps due to interbreeding with other populations such as Neanderthals.

    "This really upsets a lot of ideas, but at the same time, it's understandable if we accept that human populations were structured in the past so that there were little pockets of diversity," said Michael Hammer, an evolutionary biologist at the University of Arizona who is one of the authors of a study published in the American Journal of Human Genetics.

    The study focuses on the analysis of a DNA sample that was obtained from an African-American living in South Carolina and submitted to the Genographic Project, a National Geographic effort aimed at mapping human origins and migration. The funny thing about this sample is that it didn't match up with any of the previously known genetic signatures for the Y chromosome, which is passed down from father to son.

    "Nobody expected to find anything like this," Hammer said in a news release.

    A team led by Fernando Mendez, a researcher in Hammer's lab, analyzed more than 240,000 DNA base pairs on the African-American's Y chromosome. A comparison of the differences between the mystery genetic signature and previously known signatures led the team to conclude that the most recent common ancestor for the entire group lived about 338,000 years ago.

    That goes further back than the fossil record goes for anatomically modern humans, Hammer said. "The fossil record speaks to 195,000 years or 200,000 years," he said. It also goes further back than the previous date for the most recent common ancestor based on Y-chromosome analysis, which is in the range of 142,000 years.

    The researchers followed up on their discovery by searching through a genetic database for African populations, and turned up 11 men from western Cameroon who had virtually the same genetic signature.

    Hammer said there could be two explanations for the previously unidentified Y-chromosome type: Either the genetic heritage of anatomically correct humans really does go back much further than what's reflected in the fossil record — or other populations, such as Neanderthals or the more recently identified Denisovans, interbred with modern humans. Anthropologists refer to that pattern of divergence followed by renewed interbreeding as introgression.

    The results are "more consistent with introgression of an odd lineage," Hammer told NBC News. Over the past few years, scientists have been coming around to the view that such interbreeding did take place early in the history of our species. Recent analysis of Neanderthal and Denisovan DNA has indicated that a part of their genetic heritage survives in modern-day humans.

    Melissa Wilson Sayres, a geneticist at the University of California at Berkeley who played no role in Hammer's study, said the new findings were "exciting" because they pointed to a Y-chromosome lineage more ancient than any others. "They just happened to come across this one Y chromosome that was hidden for so long, and it's very likely that there are more hidden Y chromosomes around the world," she told NBC News.

    She said one of the biggest debates in the study of human genetics has to do with how to match mutation rates with time scales — and she expects this latest study to add to the debate. For example, some might continue to argue that the most recent common ancestor lived more recently than 338,000 years ago. "It will still be the oldest Y-chromosome heritage that we have, but I can foresee that some people might disagree with that specific age," she said.

    More about our genetic origins:

    In addition to Hammer and Mendez, the authors of "An African American Paternal Lineage Adds an Extremely Ancient Root to the Human Y Chromosome Phylogenetic Tree" include Thomas Krahn, Bonnie Schrack, Astrid-Maria Krahn, Krishna R. Veeramah, August E. Woerner, Forka Leypey Mathew Fomine, Neil Bradman, Mark G. Thomas and Tatiana M. Karafet. The authors acknowledged Jacqueline Johnson and her male cousins, the descendants of Albert Perry (South Carolina) and participating Family Tree DNA customers.

    Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

  • Big brains vs. strong immunity: Genes hint at evolutionary tug of war

    Mandel Ngan / AFP - Getty Images file

    A skull from an ancient specimen of Homo sapiens (foreground, right) is compared with a Neanderthal's skull at the Smithsonian's National Museum of Natural History in Washington. Researchers suggest that a gene linked to the immune system played a roundabout role in brain evolution.

    By Alan Boyle, Science Editor, NBC News


    Scientists say our genes contain the hints of an evolutionary tug of war that took place in the wombs of our ancestors, balancing the drive to bigger brains with the need for a strong immune system.

    The push and pull of these genetic variants apparently became more pronounced after pre-humans branched off from the ancestors of chimpanzees, according to biologists Peter Parham of Stanford University and Ashley Moffett of the University of Cambridge.

    Two years ago, Parham and other researchers suggested that interbreeding with now-extinct cousins such as Neanderthals and Denisovans may have given early humans a boost of immunity. Parham says the same kind of cross-species hanky-panky may have played a role in the genetic diversity that he and Moffett discuss in a paper published online by Nature Reviews Immunology.

    "It quite nicely dovetails with all this other stuff," Parham told NBC News. "There is an inherent instability in the way the underlying mechanism works."

    How natural killers work
    The two biologists focus on how particular types of white blood cells, known as natural killer cells, work in the human immune system. In addition to fighting infections and tumors, natural killer cells help regulate the growth of the placenta during pregnancy. Humans are unique among primates in having two variants of the genes that control the receptors for natural killer cells.

    "B haplotypes are favored during reproduction. A haplotypes are more specialized toward defending against infections," Parham explained. "These are subtle effects. On average, if you're an individual that has two A haplotypes and no B haplotype, you're going to have a slightly more robust immune system in terms of dealing with disease."

    Having two B haplotypes, in contrast, would allow for a more robust placenta. That would provide the fetus in the womb with more of the nutrients needed to grow a bigger brain. "In the course of human evolution, you had the evolution of these B haplotypes, which really did enable the brain to get bigger. ... There are correlations between the size of the brain of the baby and these genetic factors," Parham said.

    A detailed analysis of human genetic diversity suggests that the genes for the B haplotype emerged in the time frame lasting from about 7 million years ago to 1.7 million years ago. That would cover a period starting with the divergence of human and chimp ancestors, and ending with the human migration out of Africa.

    The A-vs.-B breakdown is found in all present-day human populations, suggesting that both variants were important to have for different situations. Parham and Moffett speculate that the A variant was important when a population was facing a disease epidemic, while the B variant became important for brain-building once the epidemic passed.

    The role of the birth canal
    When our ancestors began walking upright, that introduced another push-pull effect for brain size. "It's difficult to document, but it's generally thought in the field of obstetrics that birthing is more difficult for humans than it is for other species," Parham said. The dimensions and layout of the human birth canal is one constraint: If a baby's skull were to get significantly bigger, it wouldn't fit through the canal.

    Scientists in Germany have captured the first video of a childbirth using an MRI scanner. TODAY.com's Richard Lui reports.

    Another constraint is pregnancy's effect on the mother's cardiovascular system. In some situations, a potentially fatal condition known as preeclampsia can occur.

    "Part of the compromise is that the human population has tolerated a certain amount of death in childbirth, due to obstructed labor or preeclampsia. ... Both of these types of death in childbirth have been quite common in our species, as has been documented in so many 19th-century novels," Parham said.

    The genetic record indicates that the human species passed through a series of "bottlenecks" in prehistoric times that reduced population diversity to perilously low levels. That's where interbreeding with Neanderthals could have played a part. "One way that modern humans replenished the genetic diversity lost in populations was through the selection of new variants ... another, and possibly more effective, mechanism was to acquire old variants by mating with archaic humans," Parham and Moffett write.

    Today, modern medicine has leveled the evolutionary playing field. But in ancient times, all these genetic and physiological factors seem to have interacted to make our brains what they are today.

    "Basically, we've got the nervous system and the brain putting pressure on the immune system and the reproductive system," Parham said.

    More about human evolution:

    Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

  • Do chimps have a sense of fair play? Study adds to evolutionary debate

    A video from Emory University's Yerkes National Primate Research Center explains how chimpanzees were tested on their preference for fair outcomes when it comes to sharing goodies.

    By Alan Boyle, Science Editor, NBC News


    Primate researchers in Georgia have laid out what they say is the best laboratory evidence yet that chimpanzees have a human-style sense of fairness. Other researchers, however, say the study is flawed — and they're sticking to their view that fairness may be a uniquely human characteristic.

    The debate focuses on a key question about human evolution: How long ago did our ancestors acquire what Abraham Lincoln called the "better angels of our nature"? These angelic traits — such as altruism, empathy and fairness — manifest themselves in behaviors that can run counter to our own self-interest.

    The latest research, published in the Proceedings of the National Academy of Sciences, argues that a sense of fair play may have arisen millions of years ago, before our ancestors split off from the evolutionary line leading to other primates. The study's principal author, Darby Proctor of Emory University's Yerkes National Primate Research Center in Atlanta, told NBC News that the research "opens up the door for exploring the evolutionary roots of fairness in non-human animals."

    "We've concluded that chimpanzees not only get very close to the human sense of fairness, but the animals may actually have exactly the same preferences as our own species," co-author Frans de Waal, director of Emory's Living Links Center, said in a university news release.

    However, the Emory group's findings run counter to what other researchers have found in their own experiments over the past few years. One of the researchers behind those earlier studies, Keith Jensen of the University of Manchester, has said "our sense of fairness is a derived trait and may be unique to the human race."

    Today, Jensen said he and his colleagues had serious reservations about the latest experiment. "I was excited to see a replication of our ultimatum game studies, seven years on, but was disappointed by the results," he told NBC News in an email.

    How the experiment was run
    The "ultimatum game" is a key concept in all these studies: The concept refers to an arrangement in which one player makes a proposal to another player to split up a reward. For example, a parent may offer six stickers to a little girl, on the condition that she divides the treasure with her brother. A researcher may offer six banana slices to a chimp, on the condition that it divides the goodies with another chimp.

    Emory University

    Researchers report that chimpanzees can change their strategy for dividing goodies, based on whether or not the chimps they're sharing with have any say over the deal.

    If the shares are totally determined by the little girl, or the first chimp, their offer to the partner tends to be as low as possible. That's what's known as the "dictator game." But if the other partner has the power to veto a deal, it gets more complex. Make too low of an offer, and the partner might reject the proposition out of spite — even though the result is that no one gets a reward. That's the "ultimatum game."

    The Georgia researchers ran a variety of games using tokens that could be traded for either equal or unequal shares of stickers (for 20 human children, ranging in age from 2 to 7) and bananas (for six adult chimpanzees). The researchers found that the results of the game were similar for the two groups.

    If the one offering the goodies was in full control of the split, that individual kept the lion's share of the goodies. The results were different if the two partners had to agree on the split, however. "Humans typically offer generous portions, such as 50 percent of the reward, to their partners, and that's exactly what we recorded in our study with chimpanzees," Proctor said.

    How the debate is playing out
    Some questions surround the study: The second partner in the ultimatum game always accepted the offer of a split, whether it was equal or unequal. That applied to the kids as well as the chimps. Such behavior might suggest that the recipients would be happy with whatever they got, and didn't care about the fairness of the deal.

    In Jensen's eyes, the fact that none of the chimps turned down an unequal split is a "fatal flaw."

    "The ultimatum game hinges on the responder," Jensen said. "If the responder didn't understand the option of refusing, I would simply say the study did not work." Similarly, the children involved in the study may have been too young to understand that they could turn down an unfair deal — something that Proctor and her colleagues admit in their study.

    They did report, however, that both the chimps and the children occasionally expressed displeasure about an unequal division. For the kids, it was voiced in complaints such as "You got more than me!" For the chimps, it took the form of spitting water at their selfish partner, or hitting a barrier between their cages.

    Proctor and her colleagues cite other studies to back up their claim that chimps are sensitive to unfairness — such as anecdotal, non-experimental reports of chimps negotiating over the division of meat, or leafy branches. But such reports aren't yet rigorous enough to resolve the debate.

    Proctor acknowledged that more research will be required to get a firmer grasp on the better angels of a chimpanzee's nature. "We can't be sure what all was going on between the chimps," Proctor said. "That's something we'd really like to explore in the future — how much communication is necessary to convey something to another chimp."

    More about the better angels of animal nature:

    In addition to Proctor and de Waal, the authors of "Chimpanzees Play the Ultimatum Game" include Rebecca Williamson and Sarah Brosnan.

    Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

Older posts