Chapter 6. Evolution of the Brain and Behavior
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By David Brown, At the very least, the new experiment reported in Science is going to make people think differently about what it means to be a “rat.” Eventually, though, it may tell us interesting things about what it means to be a human being. In a simple experiment, researchers at the University of Chicago sought to find out whether a rat would release a fellow rat from an unpleasantly restrictive cage if it could. The answer was yes. The free rat, occasionally hearing distress calls from its compatriot, learned to open the cage and did so with greater efficiency over time. It would release the other animal even if there wasn’t the payoff of a reunion with it. Astonishingly, if given access to a small hoard of chocolate chips, the free rat would usually save at least one treat for the captive — which is a lot to expect of a rat. The researchers came to the unavoidable conclusion that what they were seeing was empathy — and apparently selfless behavior driven by that mental state. “There is nothing in it for them except for whatever feeling they get from helping another individual,” said Peggy Mason, the neurobiologist who conducted the experiment along with graduate student Inbal Ben-Ami Bartal and fellow researcher Jean Decety. “There is a common misconception that sharing and helping is a cultural occurrence. But this is not a cultural event. It is part of our biological inheritance,” she added. The idea that animals have emotional lives and are capable of detecting emotions in others has been gaining ground for decades. Empathic behavior has been observed in apes and monkeys, and described by many pet owners (especially dog owners). Recently, scientists demonstrated “emotional contagion” in mice, a situation in which one animal’s stress worsens another’s. © 1996-2014 The Washington Post
The two marmosets—small, New World monkeys—had been a closely bonded couple for more than 3 years. Then, one fateful day, the female had a terrible accident. She fell out of a tree and hit her head on a ceramic vase that happened to be underneath on the forest floor. Her partner left two of their infants alone in the tree and jumped down to apparently comfort her, until she died an agonizing death a couple of hours later. According to the researchers who recorded the events with a video camera (see video above), this is the first time such compassionate mourning behavior has been observed outside of humans and chimpanzees, and it could indicate that mourning is more widespread among primates than previously thought. Humans mourn their dead, of course, and some recent studies have strongly suggested that chimpanzees do as well. Scientists have recorded cases of adult chimps apparently caring for fellow animals before they die, and chimp mothers have been observed carrying around the bodies of infants for days after their death—although scientists have debated whether the latter behavior represents true grieving or if the mothers didn’t realize their infants were really dead. But there has been little or no evidence that other primates engage in these kinds of behaviors. Indeed, a recent review of the evidence led by anthropologist Peter Fashing of California State University, Fullerton, concluded that there were no convincing observations of “compassionate caretaking” of dying individuals among other nonhuman primates, such as monkeys. © 2014 American Association for the Advancement of Science.
James Gorman Crows and their relatives, like jays and rooks, are definitely in the gifted class when it comes to the kinds of cognitive puzzles that scientists cook up. They recognize human faces. They make tools to suit a given problem. Sometimes they seem, as humans like to say, almost human. But the last common ancestor of humans and crows lived perhaps 300 million years ago, and was almost certainly no intellectual giant. So the higher levels of crow and primate intelligence evolved on separate tracks, but somehow reached some of the same destinations. And scientists are now asking what crows can’t do, as one way to understand how they learn and how their intelligence works. One very useful tool for this research comes from an ancient Greek (or perhaps Ethiopian), the fabulist known as Aesop. One of his stories is about a thirsty crow that drops pebbles into a pitcher to raise the level of water high enough that it can get a drink. Researchers have modified this task by adding a floating morsel of food to a tube with water and seeing which creatures solve the problem of using stones to raise the water enough to get the food. It can be used for a variety of species because it’s new to all of them. “No animal has a natural predisposition to drop stones to change water levels,” said Sarah Jelbert, a Ph.D. student at Auckland University in New Zealand, who works with crows. But in the latest experiment to test the crows, Ms. Jelbert, working with Alex Taylor and Russell Gray of Auckland and Lucy Cheke and Nicola Clayton of the University of Cambridge in England, found some clear limitations to what the crows can learn. And those limitations provide some hints to how they think. © 2014 The New York Times Company
Claudia Dreifus To Neil H. Shubin’s long résumé — paleontologist, molecular biologist, dean and professor of anatomy at the University of Chicago School of Medicine, best-selling author — can now be added “television host.” Dr. Shubin, 53, who helped discover the 375-million-year-old fish called Tiktaalik, hailed as a missing link between sea and land animals, will preside over “Your Inner Fish,” a three-part series on evolution (based on his book of the same title) that makes its debut Wednesday on PBS. We spoke in Chicago in February and in New York last month. What follows is an edited and condensed version of the conversations. Q. Where did you grow up? A. Suburban Philadelphia. My mom’s a retired nursing home administrator. My father, Seymour Shubin, is a fiction writer. He writes mysteries. My favorite is “The Captain”; it won an Edgar award. He’s an educated man, but science kind of scares him. So when I’m writing, my dad is my target audience. Whenever I hit a tricky scientific concept, I think, “How would I communicate this to him?” This is why my books are written, intentionally, without jargon, which can lead to some gyrations because jargon does have precision. The funny thing is, I’m not sure he always gets what I do. When I first started working on the book version of “Your Inner Fish,” he asked, “Neil, how did you become a scientist?” I thought, “All these years he’s seen me run off to the Arctic, but he’s never been quite sure what I do up there.” So let me ask you his question: How did you become a paleontologist? I was one of those kids with lots of hobbies: astronomy, dinosaurs, collecting rocks, collecting stamps. It all came together when I went to college in New York — Columbia — and volunteered at the American Museum of Natural History. That place was like a playground for me. © 2014 The New York Times Company
Link ID: 19466 - Posted: 04.10.2014
Neandertals and modern Europeans had something in common: They were fatheads of the same ilk. A new genetic analysis reveals that our brawny cousins had a number of distinct genes involved in the buildup of certain types of fat in their brains and other tissues—a trait shared by today’s Europeans, but not Asians. Because two-thirds of our brains are built of fatty acids, or lipids, the differences in fat composition between Europeans and Asians might have functional consequences, perhaps in helping them adapt to colder climates or causing metabolic diseases. “This is the first time we have seen differences in lipid concentrations between populations,” says evolutionary biologist Philipp Khaitovich of the CAS-MPG Partner Institute for Computational Biology in Shanghai, China, and the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, lead author of the new study. “How our brains are built differently of lipids might be due to Neandertal DNA.” Ever since researchers at the Max Planck sequenced the genome of Neandertals, including a super high-quality genome of a Neandertal from the Altai Mountains of Siberia in December, researchers have been comparing Neandertal DNA with that of living people. Neandertals, who went extinct 30,000 years ago, interbred with modern humans at least once in the past 60,000 years, probably somewhere in the Middle East. Because the interbreeding happened after moderns left Africa, today’s Africans did not inherit any Neandertal DNA. But living Europeans and Asians have inherited a small amount—1% to 4% on average. So far, scientists have found that different populations of living humans have inherited the Neandertal version of genes that cause diabetes, lupus, and Crohn’s disease; alter immune function; and affect the function of the protein keratin in skin, nails, and hair. © 2014 American Association for the Advancement of Science.
By NATALIE ANGIER The “Iliad” may be a giant of Western literature, yet its plot hinges on a human impulse normally thought petty: spite. Achilles holds a festering grudge against Agamemnon (“He cheated me, wronged me ... He can go to hell...”) turning down gifts, homage, even the return of his stolen consort Briseis just to prolong the king’s suffering. Now, after decades of focusing on such staples of bad behavior as aggressiveness, selfishness, narcissism and greed, scientists have turned their attention to the subtler and often unsettling theme of spite — the urge to punish, hurt, humiliate or harass another, even when one gains no obvious benefit and may well pay a cost. Psychologists are exploring spitefulness in its customary role as a negative trait, a lapse that should be embarrassing but is often sublimated as righteousness, as when you take your own sour time pulling out of a parking space because you notice another car is waiting for it and you’ll show that vulture who’s boss here, even though you’re wasting your own time, too. Evolutionary theorists, by contrast, are studying what might be viewed as the brighter side of spite, and the role it may have played in the origin of admirable traits like a cooperative spirit and a sense of fair play. The new research on spite transcends older notions that we are savage, selfish brutes at heart, as well as more recent suggestions that humans are inherently affiliative creatures yearning to love and connect. Instead, it concludes that vice and virtue, like the two sides of a V, may be inextricably linked. “Spitefulness is such an intrinsically interesting subject, and it fits with so many people’s everyday experience, that I was surprised to see how little mention there was of it in the psychology literature,” said David K. Marcus, a psychologist at Washington State University. At the same time, he said, “I was thrilled to find something that people haven’t researched to exhaustion.” © 2014 The New York Times Company
By SINDYA N. BHANOO Monogamy is rare in animals. Even among species that pair off, there is often philandering. But a new genetic analysis adds to the evidence that the South American primates called Azara’s owl monkeys are remarkably faithful to their partners. The study confirms what one of its authors, Eduardo Fernandez-Duque, an evolutionary anthropologist at the University of Pennsylvania who leads the Owl Monkey Project, had long suspected. For 18 years, he and other Penn researchers have been observing the Azara’s owl monkey in the Chaco region of Argentina. Not only have they never witnessed a philanderer, but they have also found that infant owl monkeys get an unusual amount of care from their fathers. “The male plays with the infant and the male shares food with the infant even more than the mother,” Dr. Fernandez-Duque said. “The males care because these are their offspring, and this has a direct benefit in terms of reproductive success.” In the new study, published in the Proceedings of the Royal Society B, the researchers performed genetic analysis on 35 offspring born to 17 owl monkey pairs and confirmed that the parents were monogamous for the mating season. The monkey is the first primate and only the fifth mammal for which monogamy has been verified through genetics. Because paternal care is also seen in other species of owl monkeys, the scientists suspect that they, too, are serially monogamous. © 2014 The New York Times Company
by Hal Hodson Software has performed the first real-time translation of a dolphin whistle – and better data tools are giving fresh insights into primate communication too IT was late August 2013 and Denise Herzing was swimming in the Caribbean. The dolphin pod she had been tracking for the past 25 years was playing around her boat. Suddenly, she heard one of them say, "Sargassum". "I was like whoa! We have a match. I was stunned," says Herzing, who is the director of the Wild Dolphin Project. She was wearing a prototype dolphin translator called Cetacean Hearing and Telemetry (CHAT) and it had just translated a live dolphin whistle for the first time. It detected a whistle for sargassum, or seaweed, which she and her team had invented to use when playing with the dolphin pod. They hoped the dolphins would adopt the whistles, which are easy to distinguish from their own natural whistles – and they were not disappointed. When the computer picked up the sargassum whistle, Herzing heard her own recorded voice saying the word into her ear. As well as boosting our understanding of animal behaviour, the moment hints at the potential for using algorithms to analyse any activity where information is transmitted – including our daily activities (see "Scripts for life"). "It sounds like a fabulous observation, one you almost have to resist speculating on. It's provocative," says Michael Coen, a biostatistician at the University of Wisconsin-Madison. © Copyright Reed Business Information Ltd.
Ewen Callaway An equine oddity with the head of a zebra and the rump of a donkey, the last quagga (Equus quagga quagga) died in 1883. A century later, researchers published1 around 200 nucleotides sequenced from a 140-year-old piece of quagga muscle. Those scraps of DNA — the first genetic secrets pulled from a long-dead organism — revealed that the quagga was distinct from the mountain zebra (Equus zebra). More significantly, the research showed that from then on, examining fossils would no longer be the only way to probe extinct life. “If the long-term survival of DNA proves to be a general phenomenon,” geneticists Russell Higuchi and Allan Wilson of the University of California, Berkeley, and their colleagues noted in their quagga paper1, “several fields including palaeontology, evolutionary biology, archaeology and forensic science may benefit.” At first, progress was fitful. Concerns over the authenticity of ancient-DNA research fuelled schisms in the field and deep scepticism outside it. But this has faded, thanks to laboratory rigour that borders on paranoia and sequencing techniques that help researchers to identify and exclude contaminating modern DNA. These advances have fostered an ancient-genomics boom. In the past year, researchers have unveiled the two oldest genomes on record: those of a horse that had been buried in Canadian permafrost for around 700,000 years2, and of a roughly 400,000-year-old human relative from a Spanish cavern3. A Neanderthal sequence every bit as complete and accurate as a contemporary human genome has been released4, as has the genome of a Siberian child connecting Native Americans to Europeans5. © 2014 Nature Publishing Group
by Aviva Rutkin Eureka! Like Archimedes in his bath, crows know how to displace water, showing that Aesop's fable The Crow and the Pitcher isn't purely fictional. To see if New Caledonian crows could handle some of the basic principles of volume displacement, Sarah Jelbert at the University of Auckland in New Zealand and her colleagues placed scraps of meat just out of a crow's reach, floating in a series of tubes that were part-filled with water. Objects potentially useful for bringing up the water level, like stones or heavy rubber erasers, were left nearby. The crows successfully figured out that heavy and solid objects would help them get a treat faster. They also preferred to drop objects in tubes where they could access a reward more easily, picking out tubes with higher water levels and choosing tubes of water over sand-filled ones. However, the crows failed at more challenging tasks that required an understanding of the effect of tube width or the ability to infer a hidden connection between two linked tubes. The crows displayed reasoning skills equivalent to an average 5 to 7 year old human child, the researchers claim. Previously, Eurasian jays have shown some understanding of water displacement, as have chimpanzees and orang-utans, but using similar experiments could assess and compare their skill levels. "Any animal capable of picking up stones could potentially participate," write the researchers. © Copyright Reed Business Information Ltd.
by Bethany Brookshire Spring will be here soon. And with daffodils, crocuses and other signs of spring comes a burst of birdsong as males duke it out to get female attention. While the males trill loud songs, the females sit quietly, choosing who will be the lucky male. Vocal male and quiet female songbirds are common in temperate zones, and have given rise to a common assumption. The best male songs get picked for reproduction, and this sexual selection results in complex song; females just listen and choose, so female song should be rare. After all, females don’t need to sing to attract mates. But it turns out this commonly held assumption is not true. A new study shows that the majority of females of songbird species do sing, and it’s likely that the ancestor of modern songbirds was also a vocal diva. The results challenge the old wisdom about female songbirds, and suggest that when it comes to female song, it’s not all about sex. Karan Odom, a behavioral ecologist at the University of Maryland, Baltimore County, has always been interested in birdsong. “As I began to study it in depth,” she says, “I realized there was a lot that’s unknown, and one area was the extent to which females were singing and the role that song plays in males and females.” Odom and her colleagues did a survey of 44 songbird families, going through bird handbooks and other sources to find records of whether males, females or both were singers. In results published March 4 in Nature Communications, they showed that female melodies are not rare at all. In fact, 71 percent of the species surveyed have singing ladies. So much for that quiet, retiring female bird. © Society for Science & the Public 2000 - 2013.
Matt Kaplan Humans are among the very few animals that constitute a threat to elephants. Yet not all people are a danger — and elephants seem to know it. The giants have shown a remarkable ability to use sight and scent to distinguish between African ethnic groups that have a history of attacking them and groups that do not. Now a study reveals that they can even discern these differences from words spoken in the local tongues. Biologists Karen McComb and Graeme Shannon at the University of Sussex in Brighton, UK, guessed that African elephants (Loxodonta africana) might be able to listen to human speech and make use of what they heard. To tease out whether this was true, they recorded the voices of men from two Kenyan ethnic groups calmly saying, “Look, look over there, a group of elephants is coming,” in their native languages. One of these groups was the semi-nomadic Maasai, some of whom periodically kill elephants during fierce competition for water or cattle-grazing space. The other was the Kamba, a crop-farming group that rarely has violent encounters with elephants. The researchers played the recordings to 47 elephant family groups at Amboseli National Park in Kenya and monitored the animals' behaviour. The differences were remarkable. When the elephants heard the Maasai, they were much more likely to cautiously smell the air or huddle together than when they heard the Kamba. Indeed, the animals bunched together nearly twice as tightly when they heard the Maasai. “We knew elephants could distinguish the Maasai and Kamba by their clothes and smells, but that they can also do so by their voices alone is really interesting,” says Fritz Vollrath, a zoologist at the University of Oxford, UK (see video below). © 2014 Nature Publishing Group
Why do some humans have lighter skin than others? Researchers have longed chalked up the difference to tens of thousands of years of evolution, with darker skin protecting those who live nearer to the equator from the sun’s intense radiation. But a new study of ancient DNA concludes that European skin color has continued to change over the past 5000 years, suggesting that additional factors, including diet and sexual attraction, may also be at play. Our species, Homo sapiens, first arose in Africa about 200,000 years ago, and researchers assume that its first members were as dark-skinned as Africans are today, because dark skin is advantageous in Africa. Dark skin stems from higher levels of the pigment melanin, which blocks UV light and protects against its dangers, such as DNA damage—which can lead to skin cancer—and the breakdown of vitamin B. On the other hand, skin cells need exposure to a certain amount of UV light in order to produce vitamin D. These competing pressures mean that as early humans moved away from the equator, it makes sense that their skin lightened. Recent research, however, has suggested that the picture is not so simple. For one thing, a number of genes control the synthesis of melanin (which itself comes in two different forms in humans), and each gene appears to have a different evolutionary history. Moreover, humans apparently did not begin to lighten up immediately after they migrated from Africa to Europe beginning about 40,000 years ago. In 2012, for example, a team led by Jorge Rocha, a geneticist at the University of Porto in Portugal, looked at variants of four pigmentation genes in modern Portuguese and African populations and calculated that at least three of them had only been strongly favored by evolution tens of thousands of years after humans left Africa. In January, another team, led by geneticist Carles Lalueza-Fox of the University of Barcelona in Spain, sequenced the genome of an 8000-year-old male hunter-gatherer skeleton from the site of La Braña-Arintero in Spain and found that he was dark rather than light-skinned—again suggesting that natural selection for light skin acted relatively late in prehistory. © 2014 American Association for the Advancement of Science
By PAUL VITELLO Alison Jolly, an American-born primatologist whose research in the forests of Madagascar shed new light on the evolution of social intelligence and helped disprove a longstanding scientific tenet that males were dominant in every primate species, died on Feb. 6 in Lewes, East Sussex, England. She was 76. The cause was breast cancer, said Barbara Orlando, a longtime friend. Dr. Jolly’s two major insights emerged from her 1960s field studies of the lemur, a primate whose development in relative isolation on the island of Madagascar makes the species something akin to a living fossil. Dr. Jolly cited lemurs’ complex social relationships as evidence of an unexplored trail in one of anthropology’s great mysteries: the evolution of higher intelligence. Writing in the journal Science in 1966, she suggested that the many hours lemurs spent in play, mutual grooming and social networking — activities that establish the social ties and hierarchies that determine access to food, mate selection and migration patterns — may have been as important to the evolution of intelligence as the development of weapons and tools of hunting and protection, then considered the hallmarks of evolutionary advance. More unnerving to colleagues was her discovery that in some primate species, females run the show. The finding upended a bedrock assertion in evolutionary biology — based on studies of chimpanzees and orangutans in captivity — that males dominated females in every primate species, including humans. “Females have social, spatial and feeding priority over males,” Dr. Jolly wrote in describing the feeding, mating, child-rearing and recreational habits of the ring-tailed lemur, one of about 100 recognized species of lemur, of which more than a dozen are female-dominant. Among the ring-tailed lemurs, Dr. Jolly wrote in “Lemur Behavior: A Madagascar Field Study,” “all females, whether dominant or subordinate in the female hierarchy, are dominant over males.” © 2014 The New York Times Company
Elephants, both African and Asian, have long been considered empathetic animals. They help baby elephants stuck in mud holes, use their trunks to lift other elephants that are injured or dying, and even reportedly reassure distressed individual elephants with a gentle touch of their trunk. But it’s one thing to witness something that looks like consolation, and another to prove that this is what elephants are doing. Now, scientists have shown that African elephants do indeed get distressed when they see others in trouble, and they reach out to console them—just as we do when we see someone suffering. Elephants, thus, join a short list of other animals, including great apes, canines, and some birds, that scientists have shown to reassure others. The study “is the first to investigate responses to distress by Asian elephants,” which “is inherently difficult to assess because one has to wait for opportunities to arise spontaneously,” says Shermin de Silva, an behavioral ecologist at the Uda Walawe Elephant Research Project in Sri Lanka. It would not be ethical to intentionally create stressful situations for the animals as a test, she notes—which is why, until now, researchers have had to rely on well-documented, but anecdotal observations of wild and captive elephants to back up claims that they reassure each other. Joshua Plotnik, a behavioral ecologist at Mahidol University in Kanchanaburi, Thailand, and Frans de Waal, a primatologist at Emory University, got around this problem by comparing Asian elephants’ behaviors during times of stress to periods when little upset them. For one to two weeks every month for nearly a year, Plotnik spent 30 to 180 minutes daily watching and recording 26 captive Asian elephants. The animals ranged in age from 3 to 60 years old and lived at the 30-acre Elephant Nature Park in northern Thailand. Most of the elephants, aside from mother-juvenile pairs, were unrelated, and did not live in family groups as wild elephants do. Instead, the park’s Mahouts, or keepers, organized them into six groups which they then guided through a daily routine—bathing and feeding them in the morning, and tethering them at night. But during the day, the elephants were left alone to roam and graze at will. © 2014 American Association for the Advancement of Science
It seems simple: People are more likely to cooperate if everyone plays fair. But a new study suggests that fairness itself arises from an unlikely source: spite. Researchers made a mathematical model based on the so-called ultimatum game. In it, two players are offered a reward, and the first player makes an offer for how it should be split up. If the second player agrees, then they divide it accordingly. But if the second player refuses, then neither gets the reward. As shown in the image above, depending on the interaction of the players, the outcome can be classified as altruism, cooperation, selfishness, or spite. Previous experiments have shown that, over multiple rounds of the game, a culture of cooperation evolves where everyone makes fair offers. But the new study, published online today in the Proceedings of the Royal Society B, finds that when players start out using multiple different strategies, by making fair or unfair offers, and rejecting or accepting unfair offers, some will act out of spite. These spiteful players deny the first player the reward at a cost to himself. The calculations further show that the antisocial behavior will eventually cause fairness to become the most successful option, because there is no reason to reject a fair offer. In essence, fairness evolves in spite of spite, when players start out using different strategies. Though they warn against generalizing to humans, the researchers point out that if fairness is the basis for a moral society, then paradoxically, spite may have played a role in the evolution of morality. © 2014 American Association for the Advancement of Science.
| by Isaac Saul Multi-step puzzles can be difficult for humans, but what if I told you there was a bird that could solve them on its own? In this BBC special, Dr. Alex Taylor has set up an eight-step puzzle to try and stump one of the smartest crows he's seen in captivity. They describe the puzzle as "one of the most complex tests of the animal mind ever." This isn't the first time crows' intelligence has been tested, either. Along with being problem solvers, these animals have an eerie tendency towards complex human-like memory skills. Through several different studies, we've learned that crows can recognize faces, communicate details of an event to each other and even avoid places they recognize as dangerous. This bird, dubbed "007" for its crafty mind, flies into the caged puzzle and spends only seconds analyzing the puzzle before getting down to business. Despite the puzzle's difficulty, the bird only seems to be stumped momentarily. At the end of the puzzle is a food reward, but how he gets there is what will really blow your mind. © 2014 TheHuffingtonPost.com, Inc
By Matt McGrath Environment correspondent, BBC News Successful professional cyclists are seen as more handsome than their struggling colleagues, according to new research. Women rated facial attractiveness among riders in the 2012 Tour de France, won by Britain's Sir Bradley Wiggins. The top 10% of performers were rated on average as 25% better looking than the laggards. The scientists conclude that humans have evolved to recognise athletic performance in faces. The research has been published in the Royal Society journal, Biology Letters. Some biologists argue that evolution has shaped women to select mates on the basis that they would either make good fathers or would pass on good genes. Healthy, physically fit men would on average be seen as more attractive by women. A number of other studies in recent years have suggested that women have a sophisticated radar for athletic performance, rating those with greater sporting skill as more attractive. This new work, though, set out to test if the same applied to more inherent physical qualities such as stamina and endurance. Cycle of life Dr Erik Postma, from the Institute of Evolutionary Biology at the University of Zurich, asked people to rate the attractiveness of 80 professional cyclists from the 2012 Tour de France. The cyclists were all of a similar physical stature, were tanned and around the same age. BBC © 2014
Alice Roberts Just how special do you think you are? How different do you think you are from other animals? Do you think of yourself as an animal or do you see yourself, and your fellow humans, as somehow set apart from the rest of the animal kingdom? Most of us – and I would unashamedly label us as the sensible majority of the population – accept that evolution is the best explanation for the pattern of life that we observe on the planet, both living and fossilised. However much creationists bang on about evolution being "just a theory", it beautifully explains all the evidence we have to hand (and there's masses of that: anatomical, genetic, palaeontological, embryological), without a single piece of evidence having turned up that threatens to bring the whole edifice tumbling down around our ears. So, I'm hoping you're a sensible sort of person and that you consider evolution to be as true as the spherical nature of the Earth, or the fact that the Earth orbits the sun and not vice versa. But just how comfortable are you with the idea of being a product of evolution? I think it's still, even among the most enlightened of us, really hard to come to terms with the idea that we are just another animal. A naked ape. The third chimpanzee, even. You have to admit, science has done a very good job at bringing us down a peg or two, at knocking us off the pedestal of our own construction. We can no longer view ourselves as a special creation, something created in the image of a deity and close to angels (whatever they are or look like). We can no longer see ourselves as the ultimate destination, as the pinnacle of evolution, either. Our species is just a tiny twig on the massive, dense tree of life. But that's so difficult to stomach! © 2014 Guardian News and Media Limited
By Meeri Kim, Neanderthal genes lurk among us. Small traces of Neanderthal DNA have been confirmed in the areas of the genome that affect skin and hair of modern humans, according to two new studies that also give clues as to which Neanderthal traits may have been helpful — or harmful — to the survival of our species. The studies, published online Wednesday in the journals Nature and Science, came to similar conclusions despite using vastly different methods of genomic analysis. For East Asian and European populations, genes that provide the physical characteristics of skin and hair have a high incidence of Neanderthal DNA — possibly lending toughness and insulation to weather the cold as early man emerged from Africa, the studies conclude. Neanderthals were thought to have already been adapted to a chillier, more northern environment. Perhaps most notably, Neanderthal DNA was not found in genes that influence testicles or the X chromosome, according to the Nature study, hinting that when the Neanderthal ventured outside his species for sex, the introduction of his DNA may have reduced male fertility in early humans. As a result, evolution wiped away the Neanderthal DNA that negatively affected procreation. “There’s strong evidence that when the two met and mixed, they were at the edge of biological compatibility,” said Nature study author and Harvard University geneticist David Reich. “The people who eventually survived and thrived had quite a bit of hurdles to overcome.” This is consistent with what is seen in nature: When two species mate that are sufficiently far away biologically, the resulting hybrids tend to have lowered fertility. Early humans and Neanderthals interbred about 40,000 to 80,000 years ago around the Middle East, during man’s migration out of Africa. © 1996-2014 The Washington Post