Chapter 6. Evolution of the Brain and Behavior
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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
by Susan Milius Male bee flies fooled into trying to copulate with a daisy may learn from the awkward incident. Certain orchids and several forms of South Africa’s Gorteria diffusa daisy lure pollinators by mimicking female insects. The most effective daisy seducers row a dark, somewhat fly-shaped bump on one of their otherwise yellow-to-orange petals. Males of small, dark Megapalpus capensis bee flies go wild. But tests show the daisy’s victims waste less time trying to mate with a second deceptive daisy than with the first. “Far from being slow and stupid, these males are actually quite keen observers and fairly perceptive for a fly,” says Marinus L. de Jager of Stellenbosch University in South Africa. Males’ success locating a female bee fly drops in the presence of deceitful daisies, de Jager and Stellenbosch University colleague Allan Ellis say January 29 in the Proceedings of the Royal Society B. That’s the first clear demonstration of sexual deceit’s cost to a pollinator, Ellis says. Such evolutionary costs might push the bee fly to learn from mating mistakes. How long bee flies stay daisy-wary remains unknown. In other studies, wasps tricked by an Australian orchid forgot their lesson after about 24 hours. © Society for Science & the Public 2000 - 2014
by Ashley Yeager Monkeys may have rudimentary brain wiring that later evolved into the connections that gave humans the ability to understand language, think flexibly and make decisions. Brain scans of 25 humans and 25 macaques show that 11 components of the ventrolateral frontal cortex, located behind the temples, were similarly wired in both species. The results suggest that humans did not develop completely new and specialized brain systems for certain types of complex thought, researchers report January 28 in Neuron. The scans also show that macaques do not have the lateral frontal pole, which helps humans with strategic planning, decision-making and multitasking. © Society for Science & the Public 2000 - 2014.
Link ID: 19184 - Posted: 01.30.2014
by Erika Engelhaupt Twerking is so 50 million years ago. In fact, it’s probably much older than that. Today, the provocative, butt-shaking dance move is enough of a social phenomenon to merit a word in the dictionary (with twerking defined about as tastefully as possible here by actor Morgan Freeman), but animals have been shaking their hindquarters for ages, for a variety of purposes (more on that below). Black widow spiders are the latest documented twerkers. In their case, it’s the males that shake their rears. Black widow females are aggressive predators and will immediately kill any prey detected in their webs. This presents a problem for males approaching a female to mate; in this case a literal misstep means becoming the female’s dinner. To figure out how the males avoid being eaten (at least before mating), researchers at Simon Fraser University in Canada measured vibrations created by males and by prey in webs of western black widows (Latrodectus hesperus). They compared the vibrations, and the females’ responses, to those of the hobo spider (Tegenaria agrestis), a species in which females rarely attack courting males. To capture the details of small vibrations, they used a fun tool called a laser Doppler vibrometer, which measures small changes in a laser beam aimed at a surface. Sure enough, black widow males appeared to have a death-avoidance strategy. They produced vibrations different from thrashing prey by means of “lengthy andrepeated bouts of abdominal tremulations” averaging 43 wiggles per second, the researchers report January 17 in Frontiers in Zoology. You can see a male's moves in this video: © Society for Science & the Public 2000 - 2014
Things are heating up in the world of genetics. The hot pepper (Capsicum annuum) is one of the most widely grown spice crops globally, playing an important role in many medicines, makeups, and meals worldwide. Although the plant’s so-called capsaicin chemical is well known for spicing things up, until now the genetic spark responsible for the pepper’s pungency was unknown. A team of scientists recently completed the first high-quality reference genome for the hot pepper. Comparing the pepper’s genome with that of its tame cousin, the tomato, the scientists discovered the gene responsible for fiery capsaicin production appeared in both plants. While the tomato carried four nonfunctioning copies of the gene, the hot pepper carried seven nonfunctioning copies and one functioning copy, the team reports online today in Nature Genetics. The researchers believe the pepper’s capsaicin-creating gene appeared after five mutations occurred during DNA replication, with the final mutation creating a functional copy. The mouth-burning chemicals likely protected the mutant pepper’s seeds from grazing land animals millions of years ago, giving the mutant a reproductive advantage and helping the mutant gene spread. The team says the finding could help breeders boost the pepper’s heat, nutrition, and medicinal properties. One researcher even suggests that geneticists could activate one of the tomato’s dormant genes, enabling capsaicinoid production and creating a plant that makes ready-made salsa. © 2014 American Association for the Advancement of Science.
Imagine a couple of million years ago, a curious young alien from the planet Zantar — let's call him a grad student — lands on Earth, looks around and asks, "Who's the brainiest critter on this planet? Relative to body size, who's got the biggest brain?" The answer, back then, would not have been us. (Two million years ago, apes — even walking ones — had much smaller brains.) The brainiest weren't ancestral crows or parrots or magpies or ravens or elephants or colonies of ants or bees or termites. The Earthlings with the biggest brains back then were dolphins (and certain whales). The Zantarian grad student would have wanted to meet them. A visitor from Zantar and a dolphin check each other out. But had the grad student arrived earlier, dolphins wouldn't have been the champs, because evolution is always changing life. , at Emory University in Atlanta, has been studying fossilized brains. And looking back, she sees sudden spurts of brain growth in different animals. "[T]he most dramatic increase in brain-to-body ratio in dolphins and toothed whales occurred 35 million years ago," she tells Chris Impey, the astronomer and writer, in Talking About Life. Something happened to make their medium-sized brains bigger, Lori says, then bigger still. For 20 million years certain dolphin species kept their brains growing until — just as mysteriously as it started — about 15 million years ago, they stopped. Why? Had the dolphins answered some secret dolphin question? Figured out a puzzle? Adapted to an environmental change? Gotten tired? Hit a limit? What? Dolphin says, "Enough." ©2014 NPR