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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Do chins have a purpose?

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Ed Wong writes: “Little pig, little pig, let me come in,” says the big, bad wolf. “No, no, not by the hair on my chinny chin chin,” say the three little pigs. This scene is deeply unrealistic and not just because of the pigs’ architectural competence, the wolf’s implausible lung capacity, and everyone’s ability to talk.

The thing is: Pigs don’t have chins. Nor do any animals, except for us.

The lower jaw of a chimpanzee or gorilla slopes backwards from the front teeth. So did the jaw of other hominids like Homo erectus. Even Neanderthal jaws ended in a flat vertical plane. Only in modern humans does the lower jaw end in a protruding strut of bone. A sticky-outy bit. A chin.

“It’s really strange that only humans have chins,” says James Pampush from Duke University. “When we’re looking at things that are uniquely human, we can’t look to big brains or bipedalism because our extinct relatives had those. But they didn’t have chins. That makes this immediately relevant to everyone.” Indeed, except in rare cases involving birth defects, everyone has chins. Sure, some people have less pronounced ones than others, perhaps because their lower jaws are small or they have more flesh around the area. But if you peeled back that flesh and exposed their jawbones — and maybe don’t do that — you’d still see a chin.

So, why do chins exist?

There are no firm answers, which isn’t for lack of effort. Evolutionary biologists have been proposing hypotheses for more than a century, and Pampush has recently reviewed all the major ideas, together with David Daegling. “We kept showing, for one reason or another, that these hypotheses are not very good,” he says.

The most heavily promoted explanation is that chins are adaptations for chewing — that they help to reduce the physical stresses acting upon a masticating jaw. But Pampush found that, if anything, the chin makes things worse. The lower jaw consists of two halves that are joined in the middle; when we chew, we compress the bone on the outer face of this join (near the lips) and pull on the bone on the inner face (near the tongue). Since bone is much stronger when compressed than pulled, you’d ideally want to reinforce the inner face of the join and not the outer one. In other words, you’d want the opposite of a chin. [Continue reading…]

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Finding a hunter-gatherer massacre scene that may change history of human warfare

By Marta Mirazon Lahr, University of Cambridge

The area surrounding Lake Turkana in Kenya was lush and fertile 10,000 years ago, with thousands of animals – including elephants, giraffes and zebras – roaming around alongside groups of hunter gatherers. But it also had a dark side. We have discovered the oldest known case of violence between two groups of hunter gatherers took place there, with ten excavated skeletons showing evidence of having been killed with both sharp and blunt weapons.

The findings, published in Nature, are important because they challenge our understanding of the roots of conflict and suggest warfare may have a much older history than many researchers believe.

Shocking finding

Our journey started in 2012, when Pedro Ebeya, one of our Turkana field assistants, reported seeing fragments of human bones on the surface at Nataruk. Located just south of Lake Turkana, Nataruk is today a barren desert, but 10,000 years ago was a temporary camp set up by a band of hunter-gatherers next to a lagoon. I led a team of researchers, as part of the In-Africa project, which has been working in the area since 2009. We excavated the remains of 27 people – six young children, one teenager and 20 adults. Twelve of these – both men and women – were found as they had died, unburied, and later covered by the shallow water of the lagoon.

Ten of the 12 skeletons show lesions caused by violence to the parts of the body most commonly involved in cases of violence. These include one where the projectile was still embedded in the side of the skull; two cases of sharp-force trauma to the neck; seven cases of blunt and/or sharp-force trauma to the head; two cases of blunt-force trauma to the knees and one to the ribs. There were also two cases of fractures to the hands, possibly caused while parrying a blow.

[Read more…]

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The new atheists’ faith in demons

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John Gray writes: An American scientist visiting the home of Niels Bohr, the Nobel Prize-winning Danish physicist and refugee from Nazism who was a leading figure in the Manhattan Project, which produced the atomic bomb, was surprised to discover a horseshoe hanging over Bohr’s desk: “Surely you don’t believe the horseshoe will bring you good luck, Professor Bohr?” he asked. “After all, as a scientist . . .”

Bohr laughed. “I believe no such thing, my good friend. Not at all. I am scarcely likely to believe such foolish nonsense. However, I am told that a horseshoe will bring one good luck whether you believe it or not.”

Dominic Johnson, who tells this story, acknowledges that Bohr might have been joking. But the physicist’s response captured an important truth. Human beings never cease looking for a pattern in events that transcends the workings of cause and effect. No matter how much they may think their view of the world has been shaped by science, they cannot avoid thinking and acting as if their lives are subject to some kind of non-human oversight. As Johnson puts it, “Humans the world over find themselves, consciously or subconsciously, believing that we live in a just world or a moral universe, where people are supposed to get what they deserve. Our brains are wired such that we cannot help but search for meaning in the randomness of life.”

An evolutionary biologist trained at Oxford who also holds a doctorate in political science, Johnson believes that the need to find a more-than-natural meaning in natural events is universal – “a ubiquitous phenomenon of human nature” – and performs a vital role in maintaining order in society. Extending far beyond cultures shaped by monotheism, it “spans cultures across the globe and every historical period, from indigenous tribal societies . . . to modern world religions – and includes atheists, too”.

Reward and punishment may not emanate from a single omnipotent deity, as imagined in Western societies. Justice may be dispensed by a vast unseen army of gods, angels, demons and ghosts, or else by an impersonal cosmic process that rewards good deeds and punishes wrongdoing, as in the Hindu and Buddhist conception of karma. But some kind of moral order beyond any human agency seems to be demanded by the human mind, and this sense that our actions are overseen and judged from beyond the natural world serves a definite evolutionary role. Belief in supernatural reward and punishment promotes social co-operation in a way nothing else can match. The belief that we live under some kind of supernatural guidance is not a relic of superstition that might some day be left behind but an evolutionary adaptation that goes with being human.

It’s a conclusion that is anathema to the current generation of atheists – Richard Dawkins, Daniel Dennett, Sam Harris and others – for whom religion is a poisonous concoction of lies and delusion. These “new atheists” are simple souls. In their view, which derives from rationalist philosophy and not from evolutionary theory, the human mind is a faculty that seeks an accurate representation of the world. This leaves them with something of a problem. Why are most human beings, everywhere and at all times, so wedded to some version of religion? It can only be that their minds have been deformed by malignant priests and devilish power elites. Atheists have always been drawn to demonology of this kind; otherwise, they cannot account for the ­persistence of the beliefs they denounce as poisonously irrational. The inveterate human inclination to religion is, in effect, the atheist problem of evil. [Continue reading…]

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Evidence of a prehistoric massacre extends the history of warfare

University of Cambridge: Skeletal remains of a group of foragers massacred around 10,000 years ago on the shores of a lagoon is unique evidence of a violent encounter between clashing groups of ancient hunter-gatherers, and suggests the “presence of warfare” in late Stone Age foraging societies.

The fossilised bones of a group of prehistoric hunter-gatherers who were massacred around 10,000 years ago have been unearthed 30km west of Lake Turkana, Kenya, at a place called Nataruk.

Researchers from Cambridge University’s Leverhulme Centre for Human Evolutionary Studies (LCHES) found the partial remains of 27 individuals, including at least eight women and six children.

Twelve skeletons were in a relatively complete state, and ten of these showed clear signs of a violent death: including extreme blunt-force trauma to crania and cheekbones, broken hands, knees and ribs, arrow lesions to the neck, and stone projectile tips lodged in the skull and thorax of two men.

Several of the skeletons were found face down; most had severe cranial fractures. Among the in situ skeletons, at least five showed “sharp-force trauma”, some suggestive of arrow wounds. Four were discovered in a position indicating their hands had probably been bound, including a woman in the last stages of pregnancy. Foetal bones were uncovered.

The bodies were not buried. Some had fallen into a lagoon that has long since dried; the bones preserved in sediment.

The findings suggest these hunter-gatherers, perhaps members of an extended family, were attacked and killed by a rival group of prehistoric foragers. Researchers believe it is the earliest scientifically-dated historical evidence of human conflict – an ancient precursor to what we call warfare.

[Read more…]

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Humans inhabited Arctic 45,000 years ago

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Science magazine reports: In August of 2012, an 11-year-old boy made a gruesome discovery in a frozen bluff overlooking the Arctic Ocean. While exploring the foggy coast of Yenisei Bay, about 2000 kilometers south of the North Pole, he came upon the leg bones of a woolly mammoth eroding out of frozen sediments. Scientists excavating the well-preserved creature determined that it had been killed by humans: Its eye sockets, ribs, and jaw had been battered, apparently by spears, and one spear-point had left a dent in its cheekbone — perhaps a missed blow aimed at the base of its trunk.

When they dated the remains, the researchers got another surprise: The mammoth died 45,000 years ago. That means that humans lived in the Arctic more than 10,000 years earlier than scientists believed, according to a new study. The find suggests that even at this early stage, humans were traversing the most frigid parts of the globe and had the adaptive ability to migrate almost everywhere.

Most researchers had long thought that big-game hunters, who left a trail of stone tools around the Arctic 12,500 years ago, were the first to reach the Arctic Circle. These cold-adapted hunters apparently traversed Siberia and the Bering Straits at least 15,000 years ago (and new dates suggest humans may have been in the Americas as early as 18,500 years ago).

But in 2004, researchers pushed that date further back in time when they discovered beads and stone and bone tools dated to as much as 35,000 years old at several sites in the Ural Mountains of far northeastern Europe and in northern Siberia; they also found the butchered carcasses of woolly mammoths, woolly rhinoceros, reindeer, and other animals.

The Russian boy’s discovery — of the best-preserved mammoth found in a century — pushes back those dates by another 10,000 years. [Continue reading…]

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Here’s how genetics helped crack the history of human migration

By George Busby, University of Oxford

Over the past 25 years, scientists have supported the view that modern humans left Africa around 50,000 years ago, spreading to different parts of the world by replacing resident human species like the Neanderthals. However, rapid advances in genetic sequencing have opened up a whole new window into the past, suggesting that human history is much more complicated.

In fact, genetic studies in the last few years have revealed that since our African exodus, humans have moved and mixed a lot more than previously thought – particularly over the last 10,000 years.

The technology

Our ability to sequence DNA has increased dramatically since the human genome was first sequenced 15 years ago. In its most basic form, genetic analysis involves comparing DNA from different sets of people, whether between people with or without a particular type of cancer, or individuals from different regions of the world.

The human genome is 3 billion letters long, but as people differ at just one letter in every thousand, on average, we don’t have to look at them all. Instead, we can compare people where we know there are these differences, known as genetic markers. Millions of these markers have been discovered and, together with a genetic sequencing technology that allows us to cheaply look at these markers in lots of people, there has been an explosion in the data available to geneticists.

[Read more…]

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Pathogens found in Otzi’s stomach reveal unexpected insights into the coexistence of humans and bacterium

The European Academy of Bozen/Bolzano (EURAC) reports: Scientists are continually unearthing new facts about Homo sapiens from the mummified remains of Ötzi, the Copper Age man, who was discovered in a glacier in 1991. Five years ago, after Ötzi’s genome was completely deciphered, it seemed that the wellspring of spectacular discoveries about the past would soon dry up. An international team of scientists working with paleopathologist Albert Zink and microbiologist Frank Maixner from the European Academy (EURAC) in Bozen/Bolzano have now succeeded in demonstrating the presence of Helicobacter pylori in Ötzi’s stomach contents, a bacterium found in half of all humans today. The theory that humans were already infected with this stomach bacterium at the very beginning of their history could well be true. The scientists succeeded in decoding the complete genome of the bacterium.

When EURAC’s Zink and Maixner first placed samples from the Iceman’s stomach under the microscope in their ancient DNA Lab at EURAC, almost three years ago, they were initially sceptical.

“Evidence for the presence of the bacterium Helicobacter pylori is found in the stomach tissue of patients today, so we thought it was extremely unlikely that we would find anything because Ötzi’s stomach mucosa is no longer there,” explains Zink. Together with colleagues from the Universities of Kiel, Vienna and Venda in South Africa as well as the Max Planck Institute for the Science of Human History in Jena, the scientists tried to find a new way to proceed. “We were able to solve the problem once we hit upon the idea of extracting the entire DNA of the stomach contents,” reports Maixner. “After this was successfully done, we were able to tease out the individual Helicobacter sequences and reconstruct a 5,300 year old Helicobacter pylori genome.” [Read more…]

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Why wealth hasn’t brought health: The body isn’t built to be an exclusive neighborhood

microbiome

Matt Ridley writes: As Stewart Brand acutely says, most of the things that dominate the news are not really new: love, scandal, crime, and war come round again and again. Only science and invention deliver truly new stuff, like double helixes and search engines. In this respect, the new news from recent science that most intrigues me is that we may have a way to explain why certain diseases are getting worse as we get richer. We are defeating infectious diseases, slowing or managing many diseases of ageing like heart disease and cancer, but we are faced with a growing epidemic of allergy, auto-immunity, and things like autism. Some of it is due to more diagnosis, some of it is no doubt hypochondria, but there does seem to be a real increase in these kinds of problems.

Take hay fever. It is plainly a modern disease, far more common in urban, middle-class people than it used to be in peasants in the past, or still is in subsistence farmers in Africa today. There’s really good timeline data on this, chronicling the appearance of allergies as civilization advances, province by province or village by village. And there’s really good evidence that what causes this is the suppression of parasites. You can see this happen in eastern Europe and in Africa in real time: get rid of worms and a few years later children start getting hay fever. Moises Velasquez-Manoff chronicles this in glorious detail in his fine book An Epidemic of Absence.

This makes perfect sense. In the arms race with parasites, immune systems evolved to “expect” to be down-regulated by parasites, so they over-react in their absence. A good balance is reached when parasites try down-regulating the immune system, but it turns rogue when there are no parasites. [Continue reading…]

Nina Jablonski writes: The taxonomic diversity and census of our resident bacteria are more than just subjects of scientific curiosity; they matter greatly to our health. The normal bacteria on our skin, for instance, are essential to maintaining the integrity of the skin’s barrier functions. Many diseases, from psoriasis to obesity, inflammatory bowel disease, some cancers, and even cardiovascular disease, are associated with shifts in our microbiota.

While it’s too early to tell if the changing bacteria are the cause or the result of these problems, the discovery of robust associations between bacterial profiles and disease states opens the door for new treatments and targeted preventive measures. The body’s microbiota also affects and is affected by the body’s epigenome, the chemical factors influencing gene expression. Thus, the bugs on us and in us are controlling the normal action of genes in the cells of our bodies, and changes in the proportions or overall numbers of bacterial affect how our cells work and respond to stress.

Let’s stop thinking about our bodies as temples of sinew and cerebrum, and instead as evolving and sloshing ecosystems full of bacteria, which are regulating our health in more ways than we could ever imagine. As we learn more about our single-celled companions in the coming years, we will take probiotics for curing acute and chronic diseases, we’ll undertake affirmative action to maintain diversity of our gut microflora as we age, and we’ll receive prescriptions for increasingly narrow-spectrum antibiotics to exterminate only the nastiest of the nasties when we have a serious acute infection. Hand sanitizers and colon cleansing will probably be with us for some time, but it’s best just to get used to it now: Bugs R us. [Continue reading…]

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New human species may rewrite history

New Scientist reports: We may have lived alongside an archaic human species just 10,500 years ago in China. Controversial bone discoveries suggest we even interbred with and cannibalised these mystery hominins.

Some think the findings could overturn our understanding of what it means to be human. “If true, this would be rather spectacular and it would make the finds of truly global importance,” says Michael Petraglia at the University of Oxford, who wasn’t involved in the discoveries.

One of the most exciting finds is a hominin femur found in Muladong cave in south-west China, alongside other human and animal bones. It shows evidence of having been burned in a fire that was used for cooking other meat, and has marks consistent with it being butchered. It has also been broken in a way that is used to access bone marrow. Unusually, it has been painted with a red clay called ochre, associated with burial rituals (PLoS One, doi.org/97c).

Things got more interesting when the team tried to identify the bone. “Our work shows clearly that the femur resembles archaic humans,” says Darren Curnoe of the University of New South Wales in Sydney, Australia, who led the team behind the discoveries. Yet the sediment the bone was found in dates to just 14,000 years ago. This would make it the most recent human species to go extinct. [Continue reading…]

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The migrant roots of ancient European ancestry

University of Cambridge

The first sequencing of ancient genomes extracted from human remains that date back to the Late Upper Palaeolithic period over 13,000 years ago has revealed a previously unknown “fourth strand” of ancient European ancestry.

This new lineage stems from populations of hunter-gatherers that split from western hunter-gatherers shortly after the ‘out of Africa’ expansion some 45,000 years ago and went on to settle in the Caucasus region, where southern Russia meets Georgia today.

Here these hunter-gatherers largely remained for millennia, becoming increasingly isolated as the Ice Age culminated in the last ‘Glacial Maximum’ some 25,000 years ago, which they weathered in the relative shelter of the Caucasus mountains until eventual thawing allowed movement and brought them into contact with other populations, likely from further east.

This led to a genetic mixture that resulted in the Yamnaya culture: horse-borne Steppe herders that swept into Western Europe around 5,000 years ago, arguably heralding the start of the Bronze Age and bringing with them metallurgy and animal herding skills, along with the Caucasus hunter-gatherer strand of ancestral DNA – now present in almost all populations from the European continent.

The research was conducted by an international team led by scientists from Cambridge University, Trinity College Dublin and University College Dublin. The findings were published last month in the journal Nature Communications.

[Read more…]

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The holly and the ivy: How pagan practices found their way into Christmas

By Peter Glaves, Northumbria University, Newcastle

Every year, almost without thinking about it, we incorporate certain plant species into out Christmas celebrations. The most obvious is the Christmas tree, linked historically in England to Prince Albert – but its use in British homes goes back to at least 1761 when Charlotte wife of George III put up a tree at the royal court.

(It’s probably worth noting here that the first artificial-brush Christmas tree was produced using the same machinery that was originally designed to produce toilet brushes.)

Three other plants are intimately associated with Christmas: holly, ivy and mistletoe – and in all cases their ecology is closely linked to their cultural uses.

[Read more…]

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Humans sleep less but more deeply than any other primate

Carl Zimmer writes: Over the past few million years, the ancestors of modern humans became dramatically different from other primates. Our forebears began walking upright, and they lost much of their body hair; they gained precision-grip fingers and developed gigantic brains.

But early humans also may have evolved a less obvious but equally important advantage: a peculiar sleep pattern. “It’s really weird, compared to other primates,” said Dr. David R. Samson, a senior research scientist at Duke University.

In the journal Evolutionary Anthropology, Dr. Samson and Dr. Charles L. Nunn, an evolutionary biologist at Duke, reported that human sleep is exceptionally short and deep, a pattern that may have helped give rise to our powerful minds. [Continue reading…]

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6,000 years ago humans upturned 300 million years of evolution

Smithsonian.com reports: It’s hard to imagine a global force strong enough to change natural patterns that have persisted on Earth for more than 300 million years, but a new study shows that human beings have been doing exactly that for about 6,000 years.

The increase in human activity, perhaps tied to population growth and the spread of agriculture, seems to have upended the way plants and animals distribute themselves across the land, so that species today are far more segregated than they’ve been at any other time.

That’s the conclusion of a study appearing this week in the journal Nature, and the ramifications could be huge, heralding a new stage in global evolution as dramatic as the shift from single-celled microbes to complex organisms.

A team of researchers led by S. Kathleen Lyons, a paleobiologist at the Evolution of Terrestrial Ecosystems (ETE) program in the Smithsonian’s National Museum of Natural History, examined the distribution of plants and animals across landscapes in the present and back through the fossil record in search of patterns.

Mostly they found randomness, but throughout time, there was always a small subset of plants and animals that showed up in relationship to one another more often than can be attributed to chance. That relationship either meant that pairs of species occur together, so when you find one, you usually find the other. Or it meant the opposite: when you find one, the other is usually not present, in which case they’re considered segregated. [Continue reading…]

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Possessed by a mask

Sandra Newman writes: It is an acknowledged fact of modern life that the internet brings out the worst in people. Otherwise law-abiding citizens pilfer films and music. Eminent authors create ‘sock puppets’ to anonymously praise their own work and denigrate that of rivals. Teenagers use the internet for bullying; even more disturbingly, grown-ups bully strangers with obsessive zeal, sometimes even driving them from their homes with repeated murder threats. Porn thrives, and takes on increasingly bizarre and often disturbing forms.

Commentators seem at a loss to satisfactorily account for this surge in antisocial tendencies. Sometimes it’s blamed on a few sociopathic individuals – but the offenders include people who are impeccably decent in their offline lives. The anonymity of online life is another explanation commonly given – but these behaviours persist even when the identities of users are easily discovered, and when their real names appear directly above offensive statements. It almost seems to be a contagion issuing from the technology itself, or at least strong evidence that computers are alienating us from our humanity. But we might have a better chance of understanding internet hooliganism if we looked at another form of concealment that isn’t true concealment, but that nonetheless has historically lured people into behaving in ways that are alien to their normal selves: the mask.

There doesn’t seem to be any culture in which masks have not been used. From the Australian outback to the Arctic, from Mesolithic Africa to the United States of the 21st century, people have always made and employed masks in ways that are seemingly various and yet have an underlying commonality. Their earliest appearance is in religious ritual. [Continue reading…]

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