What I learned from tickling apes

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Frans de Waal writes: Tickling a juvenile chimpanzee is a lot like tickling a child. The ape has the same sensitive spots: under the armpits, on the side, in the belly. He opens his mouth wide, lips relaxed, panting audibly in the same “huh-huh-huh” rhythm of inhalation and exhalation as human laughter. The similarity makes it hard not to giggle yourself.

The ape also shows the same ambivalence as a child. He pushes your tickling fingers away and tries to escape, but as soon as you stop he comes back for more, putting his belly right in front of you. At this point, you need only to point to a tickling spot, not even touching it, and he will throw another fit of laughter.

Laughter? Now wait a minute! A real scientist should avoid any and all anthropomorphism, which is why hard-nosed colleagues often ask us to change our terminology. Why not call the ape’s reaction something neutral, like, say, vocalized panting? That way we avoid confusion between the human and the animal.

The term anthropomorphism, which means “human form,” comes from the Greek philosopher Xenophanes, who protested in the fifth century B.C. against Homer’s poetry because it described the gods as though they looked human. Xenophanes mocked this assumption, reportedly saying that if horses had hands they would “draw their gods like horses.” Nowadays the term has a broader meaning. It is typically used to censure the attribution of humanlike traits and experiences to other species. Animals don’t have “sex,” but engage in breeding behavior. They don’t have “friends,” but favorite affiliation partners.

Given how partial our species is to intellectual distinctions, we apply such linguistic castrations even more vigorously in the cognitive domain. By explaining the smartness of animals either as a product of instinct or simple learning, we have kept human cognition on its pedestal under the guise of being scientific. [Continue reading…]

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In order for our minds to go beyond syntax to semantics, we need feelings

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Stephen T Asma writes: After you spend time with wild animals in the primal ecosystem where our big brains first grew, you have to chuckle a bit at the reigning view of the mind as a computer. Most cognitive scientists, from the logician Alan Turing to the psychologist James Lloyd McClelland, have been narrowly focused on linguistic thought, ignoring the whole embodied organism. They see the mind as a Boolean algebra binary system of 1 or 0, ‘on’ or ‘off’. This has been methodologically useful, and certainly productive for the artifical intelligence we use in our digital technology, but it merely mimics the biological mind. Computer ‘intelligence’ might be impressive, but it is an impersonation of biological intelligence. The ‘wet’ biological mind is embodied in the squishy, organic machinery of our emotional systems — where action-patterns are triggered when chemical cascades cross volumetric tipping points.

Neuroscience has begun to correct the computational model by showing how our rational, linguistic mind depends on the ancient limbic brain, where emotions hold sway and social skills dominate. In fact, the cognitive mind works only when emotions preferentially tilt our deliberations. The neuroscientist Antonio Damasio worked with patients who had damage in the communication system between the cognitive and emotional brain. The subjects could compute all the informational aspects of a decision in detail, but they couldn’t actually commit to anything. Without clear limbic values (that is, feelings), Damasio’s patients couldn’t decide their own social calendars, prioritise jobs at work, or even make decisions in their own best interest. Our rational mind is truly embodied, and without this emotional embodiment we have no preferences. In order for our minds to go beyond syntax to semantics, we need feelings. And our ancestral minds were rich in feelings before they were adept in computations.

Our neo-cortex mushroomed to its current size less than one million years ago. That’s a very recent development when we remember that the human clade or group broke off from the great apes in Africa 7 million years ago. That future-looking, tool-wielding, symbol-juggling cortex grew on top of the limbic system. Older still is the reptile brain — the storehouse of innate motivational instincts such as pain-avoidance, exploration, hunger, lust, aggression and so on. Walking around (very carefully) on the Serengeti is like visiting the nursery of our own mind. [Continue reading…]

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‘Hobbits’ may have died out before the arrival of humans

Science News reports: Hobbits disappeared from their island home nearly 40,000 years earlier than previously thought, new evidence suggests.

This revised timeline doesn’t erase uncertainty about the evolutionary origins of these controversial Indonesian hominids. Nor will the new evidence resolve a dispute about whether hobbits represent a new species, Homo floresiensis, or were small-bodied Homo sapiens.

Hobbits vanished about 50,000 years ago at Liang Bua Cave on Flores, an island situated between Borneo and Australia’s northern coast, say archaeologist Thomas Sutikna of the University of Wollongong, Australia, and his colleagues.

Cave sediment dating to about 12,000 years ago, which lies just above soil that yielded H. floresiensis remains, provided an initial estimate of when these diminutive hominids with chimp-sized brains died out. But that sediment washed into the cave long after H. floresiensis was gone, covering much older, hobbit-bearing soil, the researchers report in the March 31 Nature. [Continue reading…]

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How the tribal warfare of our ancestors explains the rise of ISIS

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Luke Glowacki writes: Humans are hard-wired to adopt their communities’ norms, and these norms can include rules for how to treat others — including whether to tolerate differences or attack outsiders. When norms provide status, material rewards or membership in a privileged group, they become even more potent.

Cultures are able to hijack this psychology for violent ends by providing status, promises of an afterlife and a sense of meaning. People belonging to communities that advocate violence will adopt norms of violence, whether those communities are tribal societies, neighbors and family, or Facebook friends. Cross-cultural research I’ve conducted shows that the most important predictor of warfare in a society is a cultural system that awards warriors with social benefits.

In East Africa, where groups battle each other for livestock, access to grazing lands and water, conflicts are fought with modern weapons such as AK-47s but occur along tribal borders and resemble the dynamics of ancestral warfare in important ways. Access to resources such as livestock and water can be critical for a group’s survival, and so these cultures award status and livestock to successful warriors. Such warriors are able to marry more wives and have more children than other men. Half a world away, in the Venezuelan Amazon, researchers found that warriors also ended up better off than non-warriors. Over the time scales at which humans and cultures evolve, benefits such as these may have had profound significance in the development of human behavior.

Such incentives help explain how people can be lured into supporting the Islamic State. The group promises its recruits prestige, a sense of community and the possibility of glory — the same types of incentives that cultures across the globe have historically used to motivate youth to take up arms. [Continue reading…]

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What makes fighters risk their lives?

Harvey Whithouse writes: Misrata, Libya, 2011. I am ushered into the boardroom of what was once an oil investment corporation. I am surrounded by youths with Kalashnikovs. On the other side of the table are several of Libya’s most respected rebel leaders, foremost among them Salim Jawha, a former colonel in Muammar Gaddafi’s army who defected on the first day of the revolution.

In the preceding months, over 1,000 rebels have been killed and many thousands more horrifically injured. Stories of heroism are commonplace. For example, on March 6, Gaddafi’s forces — supported by seven tanks and some 25 or so vehicles with mounted machine guns — attempted to re-take the city but were ambushed and overcome by rebels. Despite the imbalance of military hardware and heavy loss of life, the rebels prevailed through astonishing courage and determination.

I’m here because I want to know what motivated thousands of civilians, most of whom had never even held a gun before, to take up arms as part of a popular uprising in which death was far likelier than victory. A more general version of this question has been guiding my research for some years, in my work with a wide variety of military groups ranging from tribal warriors in the rainforests of Papua New Guinea to highly trained soldiers in the British special forces and Royal Marines. One of the themes that continually surfaces in these conversations is that fighters don’t put their lives on the line for abstract values like “king and country” or “God, freedom, and democracy.” They do it for each other.

At the University of Oxford, I lead an international network of researchers dedicated to understanding what makes bonds so strong that people will fight and die for the group when it is threatened. Our research suggests that one of the most powerful causes of extreme pro-group action is the sharing of self-defining experiences. If so, this has profound implications for the way we should approach conflict resolution and counter-terrorism. Public debate and policymaking has been dominated for years by the view that extreme beliefs are what motivate extreme behaviors. I disagree — but with such a tide of popular opinion against me, I need evidence not only from the laboratory or even from the assault course and training camp, but also from the frontlines. This has brought me to Libya. [Continue reading…]

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Slaughter at the bridge: Uncovering a colossal Bronze Age battle

Andrew Curry reports: About 3200 years ago, two armies clashed at a river crossing near the Baltic Sea. The confrontation can’t be found in any history books — the written word didn’t become common in these parts for another 2000 years — but this was no skirmish between local clans. Thousands of warriors came together in a brutal struggle, perhaps fought on a single day, using weapons crafted from wood, flint, and bronze, a metal that was then the height of military technology.

Struggling to find solid footing on the banks of the Tollense River, a narrow ribbon of water that flows through the marshes of northern Germany toward the Baltic Sea, the armies fought hand-to-hand, maiming and killing with war clubs, spears, swords, and knives. Bronze- and flint-tipped arrows were loosed at close range, piercing skulls and lodging deep into the bones of young men. Horses belonging to high-ranking warriors crumpled into the muck, fatally speared. Not everyone stood their ground in the melee: Some warriors broke and ran, and were struck down from behind.

When the fighting was through, hundreds lay dead, littering the swampy valley. Some bodies were stripped of their valuables and left bobbing in shallow ponds; others sank to the bottom, protected from plundering by a meter or two of water. Peat slowly settled over the bones. Within centuries, the entire battle was forgotten. [Continue reading…]

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How we forgot how to feed ourselves

Karen Coates writes: Late in January, I boarded a long-haul flight, 27 hours and 5 minutes, 9,405 miles, three connections. I packed emergency Larabars (food for quick energy), ordered gluten-free meals (a topic for discussion another day), and thought about my meeting with the king of Boti.

Boti is a small kingdom in the Indonesian state of East Nusa Tenggara on the island of Timor. Centuries ago, this region was populated by dozens of small indigenous kingdoms, but most no longer exist in this vast and multicultural republic now united under the flag of Indonesia. Still, the villagers of Boti hold tight to their traditional customs and life from the land: They weave clothes from cotton they grow, and they never wear shoes. They make dishes from coconut shells, bags from banyan roots, candles from nuts, and tools from wood.

In 2002, my husband and I trekked 6 miles through parched, deforested hills, toward the secluded village, to meet the king, who was 96 at the time. He greeted us on his front porch. There, at his home, we were served coffee alongside bananas and sweet potatoes grown on site. The bananas were plump and juicy, not at all mealy or dull. There is a complexity to the flavor of a great banana—plucked fresh—that is experienced only in the tropics, eaten at the origins. So many wonderful bananas never make it to stores in the West.

The king, Ama Nune Benu, sat on a painted wooden chair on his porch, twisting a long root into a rope, as he told us about his way of life. “We are close with the nature,” he said. City folk are not. City folk do not work the land and grow their own food, he told us. “I have 10 fingers. If I use these 10 fingers to get something to eat, I feel better.” Processed, store-bought foods are humanity’s downfall, according to the king. [Continue reading…]

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400,000-year-old fossils from Spain provide earliest genetic evidence of Neandertals

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

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

“Sima de los Huesos is currently the only non-permafrost site that allow us to study DNA sequences from the Middle Pleistocene, the time period preceding 125,000 years ago”, says Matthias Meyer of the Max Planck Institute for Evolutionary Anthropology, lead author of an article that was published in Nature today. “The recovery of a small part of the nuclear genome from the Sima de los Huesos hominins is not just the result of our continuous efforts in pushing for more sensitive sample isolation and genome sequencing technologies”, Meyer adds. “This work would have been much more difficult without the special care that was taken during excavation.” [Continue reading…]

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What we could learn from bonobos

Cari Romm writes: In a lot of ways, we have more in common with chimpanzees than we do with bonobos. Both species of ape are considered humans’ genetically closest living relatives, but chimpanzees live in patriarchal societies, start wars with their neighbors, and, as a paper published today in Proceedings of the National Academy of Sciences put it, “do not take kindly to strangers.”

By contrast, bonobos, which form female-dominated societies, have no problem welcoming outsiders into the fold: They mate, share food, and readily form bonds with strangers. They’re also great at defusing conflicts before they escalate — when bonobos stumble upon a new feeding ground, for example, they tend to celebrate with group sex before eating, a habit researchers believe is meant to relieve tension that could otherwise translate into competition for food.

We do share some things with the warmer, fuzzier contingent of our ape family tree: In 2013, for example, researchers from Emory University found strong similarities between the emotional development of young bonobos to that of human children. But in the recent PNAS paper, a team of researchers from the Netherlands found one more difference: Where humans are primed to pay more attention to threats, bonobos are more captivated by examples of cooperation. [Continue reading…]

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Is it possible to get 15% of your calories from sugar and still be healthy?

By Claire Marriott, University of Brighton

It would be fair to say that most of us lead a life far removed from our hunter-gatherer days. Consequently, studies into remote tribes, and the effect of their diet and foraging behaviour, have been used to try to understand the effect of our modern lifestyle on conditions such as obesity and type 2 diabetes.

Members of the Hadza, a hunter-gatherer community from Tanzania, obtain 15% of their calories from honey. They have a relatively long life expectancy and little to no incidence of metabolic disease.

Research suggests that people in the UK consume an almost equivalent amount of sugar (guidelines recommend no more than 5%) yet there is an obesity epidemic, with a comparable increase in the number of people developing type 2 diabetes. So, are the guidelines wrong? Or are we simply consuming the wrong kind of sugar? If we replaced all table sugar with honey would we see a dramatic decrease in the number of people who develop type 2 diabetes?

Perhaps predictably, it’s not that simple. A hunter-gatherer tribe will spend a large proportion of their time, well, hunting and gathering – a less common urban activity these days. A diet containing such high levels of honey is going to have a very different effect on a population with higher physical activity. We would definitely need to move a lot more to earn that 15%. Although obesity is an incredibly complex condition (as the graphic below shows), the benefits of exercise on physical (and mental) well-being can’t be argued.

[Read more…]

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The secret of our evolutionary success is faith

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Brian Gallagher writes: The staunch atheist and essayist Christopher Hitchens once said that “the most overrated of the virtues is faith.” It’s a reasonable conclusion if you believe, as the astrophysicist Carl Sagan did, that “extraordinary claims require extraordinary evidence.” To believe something without evidence — or have faith — is, in their view, something to avoid (and, when called for, to mock).

Yet it was arguably faith — rather than reason — that had been instrumental to our ancestors’ survival. That’s just one of the many intriguing and paradoxical claims that Joseph Henrich, an evolutionary anthropologist at Harvard University, defends in his new book, The Secret of Our Success: How Culture Is Driving Human Evolution, Domesticating Our Species, and Making Us Smarter. His central thesis, reiterated confidently, is that natural selection — the mechanism of biological evolution — is not the “only process capable of creating complex adaptations.” Cultural evolution, he says, is quite capable of generating “complex adaptive products” essential to our survival, which no one designed or understood “before they emerged.”

Consider, for example, the art of hunting, a complex adaptive product that Henrich unpacks in a section titled “Divination and Game Theory.” To decide where to go looking for caribou, the hunters of the Naskapi tribe, in Labrador, Canada, would not do something most would consider common sense: Go to the spot where you last killed some. That tactic would be ineffective because the caribou know to avoid places where their comrades were last slayed. Of course, the Naskapi don’t realize this; the reason they don’t go to the spot of their last kill is because they rely on the result of a ritual to point the way instead. [Continue reading…]

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How humans became meat eaters

Marta Zaraska writes: Just as modern chimps occasionally hunt colobus monkeys, our ancestors may have occasionally dined on the raw meat of small monkeys, too. Yet the guts of early hominins wouldn’t have allowed them to have a meat-heavy diet, like the one Americans eat today. Their guts were characteristic of fruit-and-leaf eaters, with a big caecum, a bacteria-brimming pouch at the beginning of the large intestine. If an australopith gorged himself on meat — say, ate a few zebra steaks tartare in one sitting — he likely would have suffered twisting of the colon, with piercing stomach pains, nausea, and bloating, possibly resulting in death. And yet in spite of these dangers, by 2.5 million years ago, our ancestors had become meat eaters.

It seems that our bodies had to adjust gradually, first getting hooked on seeds and nuts, which are rich in fats but poor in fiber. If our ancestors ate a lot of them, such a diet would have encouraged the growth of the small intestine (where the digestion of lipids takes place) and the shrinking of the caecum (where fibers are digested). This would have made our guts better for processing meat. A seed-and-nut diet could have prepared our ancestors for a carnivorous lifestyle in another way, too: It could have given them the tools for carving carcasses. Some researchers suggest that the simple stone tools used for pounding seeds and nuts could have easily been reassigned to cracking animal bones and cutting off chunks of flesh. And so, by 2.5 million years ago, our ancestors were ready for meat: They had the tools to get it and the bodies to digest it.

But being capable is one thing; having the will and skill to go out and get meat is quite another. So what inspired our ancestors to look at antelopes and hippos as potential dinners? The answer, or at least a part of it, may lie in a change of climate approximately 2.5 million years ago. [Continue reading…]

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Do the Hadza give their honeyguides a fair wage?

Cara Giaimo writes: In the tree-strewn savannah of northern Tanzania, near the salty shores of Lake Eyasi, live some of the planet’s few remaining hunter-gatherers. Known as the Hadza, they live in Hadzaland, which stretches for about 4,000 square kilometers around the lake. No one is sure how long they’ve been there, but it could be since humans became human. As one anthropologist put it in a recent book, “their oral history contains no stories suggesting they came from some other place.”

Anthropologists have been scrutinizing the Hadza for centuries, seeking in their stories and behavior windows to the past. The Hadza themselves, at least at times, subscribe to a food-based method of self-understanding: they describe their predecessors based on what, and how, they ate. The first Hadza, the Akakaanebe, or “ancestors,” ate raw game, plentiful and easily slain–as one ethnographer relays, “they simply had to stare at an animal and it fell dead.” The second, the Tlaatlaanebe, ate fire-roasted meat, hunted with dogs. The third, the Hamakwabe, invented bows and arrows and cooking pots, and thus expanded the menu.

The Hamaishonebe, or “modern people” — the people of today — have a variety of meal strategies. Hadza hunting and gathering grounds are shrinking, under pressure from maize farms, herding grounds, and private game reserves, and some work jobs and buy food from their neighbors. But between two and three hundred of the 1300 Hadza remaining still survive almost entirely on wild foods: tubers, meat, fruit, and honey.

Of these staples, honey is the Hadza’s overwhelming favorite. But beehives, located high up in thick-trunked baobabs and guarded fiercely by their stinging occupants, are hard to get at, and even harder to find. Enter the greater honeyguide, an unassuming black and white bird about the size of a robin. Greater honeyguides, a distinct species within the honeyguide family, love grubs and beeswax, and are great at locating hives. This is a boon for the Hadza, who, according to some estimates, get about 15 percent of their calories from honey.

When Hadza want to find honey, they shout and whistle a special tune. If a honeyguide is around, it’ll fly into the camp, chattering and fanning out its feathers. The Hadza, now on the hunt, chase it, grabbing their axes and torches and shouting “Wait!” They follow the honeyguide until it lands near its payload spot, pinpoint the correct tree, smoke out the bees, hack it open, and free the sweet combs from the nest. The honeyguide stays and watches.

It’s one of those stories that sounds like a fable — until you get to the end, where the lesson normally goes. Then it becomes a bit more confusing. [Continue reading…]

The way this story plays out has commonly been depicted as shown in the video below, but it turns out that this relationship between humans and birds might not be quite as mutually beneficial as first thought.

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Evidence mounts for interbreeding bonanza in ancient human species

Nature reports: The discovery of yet another period of interbreeding between early humans and Neanderthals is adding to the growing sense that sexual encounters among different ancient human species were commonplace throughout their history.

“As more early modern humans and archaic humans are found and sequenced, we’re going to see many more instances of interbreeding,” says Sergi Castellano, a population geneticist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. His team discovered the latest example, which they believe occurred around 100,000 years ago, by analysing traces of Homo sapiens DNA in a Neanderthal genome extracted from a toe bone found in a cave in Siberia.

“There is this joke in the population genetics community — there’s always one more interbreeding event,” Castellano says. So before researchers discover the next one, here’s a rundown of the interbreeding episodes that they have already deduced from studies of ancient DNA. [Continue reading…]

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Race is a social construct, scientists argue

Scientific American: More than 100 years ago, American sociologist W.E.B. Du Bois was concerned that race was being used as a biological explanation for what he understood to be social and cultural differences between different populations of people. He spoke out against the idea of “white” and “black” as discrete groups, claiming that these distinctions ignored the scope of human diversity.

Science would favor Du Bois. Today, the mainstream belief among scientists is that race is a social construct without biological meaning. And yet, you might still open a study on genetics in a major scientific journal and find categories like “white” and “black” being used as biological variables.

In an article published today (Feb. 4) in the journal Science, four scholars say racial categories are weak proxies for genetic diversity and need to be phased out. [Continue reading…]

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