6 DECEMBER 2010 BY ROBERT ADLER * MAGAZINE ISSUE 2789

They were technologically savvy, creative and cultured. So maybe it’s time we accepted that Neanderthals were people just like us.

EVER since the first fossils of a brawny, low-browed, chimp-chested hominin were unearthed in Germany in 1856, Neanderthals have stirred both fascination and disdain. German pathologist Rudolf Virchow decreed that the bones belonged to a wounded Cossack whose brow ridges reflected years of pain-driven frowns. French palaeontologist Marcellin Boule recognised the fossils as ancient, but ignored signs that the specimen he studied suffered from arthritis. It was he who reconstructed the bent-kneed, shambling brute that still lurks in the back of most people’s minds. Irish geologist William King found the creature so ape-like that he considered putting it into a new genus. In the end he merely relegated it to a separate species, Homo neanderthalensis.

Since then, hundreds of Neanderthal sites have been excavated. These show that Neanderthals occupied much of modern-day Eurasia, from the British Isles to Siberia, and from the Red Sea to the North Sea. Here they survived 200,000 years or more of climatic chaos before eventually disappearing around 30,000 years ago. The long-held view that Neanderthals were inferior to Homo sapiens is changing as, one by one, capabilities thought unique to us have been linked to them. What’s more, the two species clearly crossed paths, and the publication of the Neanderthal genome earlier this year shows that they interbred. We share over 99 per cent of our genes with Neanderthals, and after splitting from a common ancestor almost 500,000 years ago anatomically modern humans met and mated with Neanderthals, most likely in the Middle East around 45,000 years ago.

If our ancestors made love, not war, the same cannot be said for the researchers who study them. The new discoveries have been pounced upon by those who believe that Neanderthals thought like we did, talked like we did and enriched their world with music, decoration and symbols as we did. It has even been suggested that we are the same species. However, there are still some who vehemently argue that Neanderthal minds were no match for those of our H. sapiens ancestor. Surprisingly, they too point to the latest genetic evidence to bolster this view. So, were Neanderthals once our equal, or just another failed species of hominin?

The first pieces of evidence to support the revisionist camp come from Neanderthal lifestyles, which indicate parallels with early modern humans. We know, for example, that in addition to occupying caves and overhangs, Neanderthals also constructed shelters. Holes for wooden pegs and posts that probably supported lean-tos have been found at two sites in France (American Anthropologist, vol 104, p 50). Numerous hearths dating from 60,000 years ago indicate that Neanderthals also controlled fire – although they were not the first to do so. They may, however, have been the first to play music around their fires. The oldest known musical instrument has been attributed to Neanderthals by its discoverer Ivan Turk (Nature, vol 460, p 737), although sceptics argue that the 43,000-year-old bone “flute” found at Divje Babe in Slovenia is just a cave bear femur punctured by wild animals (Antiquity, vol 72, p 65).

Although typecast as incapable of change, it now seems that Neanderthals did innovate

There is also evidence that Neanderthals wore clothes. And Shara Bailey at New York University thinks that, like today’s traditional Inuit, they softened animal skins with their teeth. “If you get an adult skull, their incisors are often worn down to nubs, while the molars are fine. So they were probably using their front teeth to process skins,” she says.

Initially seen as mere scavengers, it is now clear that Neanderthals hunted formidable prey, including rhinos and fully grown mammoths. They also adapted their hunting strategies to the environment, ambushing solitary prey in forests, stalking bison and other herd animals on the steppes, and harvesting birds, rabbits and seafood at the shore (Proceedings of the National Academy of Sciences, vol 105, p 14319).

Their toolkit, typical of the Mousterian culture, which dates from between 300,000 and 30,000 years ago, required planning, concentration and great skill to make. Meticulous preparation of a stone core was needed so that a final rap from a hammer stone would yield a predetermined flake tool. “They developed techniques that modern humans find difficult to replicate,” says Thomas Wynn at the University of Colorado in Colorado Springs. They even manufactured and used compound tools made from more than one material, including the first hafted spears, some 127,000 years ago (Journal of Archaeological Science, vol 36, p 850). There is also evidence dating from 80,000 years ago that they created a kind of glue with which to attach stone points to spear hafts by heating birch pitch under anaerobic conditions (Journal of European Archaeology, vol 4, p 385).

In the past it was generally believed that advances in Neanderthal technology towards the end of their era were simply copied from early modern humans, but research from 42,000-year-old Neanderthal sites in southern Italy refutes this. There, at least, Neanderthals developed an array of stone and bone tools distinct from those used by the early humans living further north (Journal of Archaeological Method and Theory, vol 17, p 175). Although Neanderthals have been typecast as incapable of change, many researchers now accept that they did innovate.

There is also widespread acceptance that Neanderthals buried their dead (Extinct Humans, Basic Books, 2000). The earliest undisputed H. sapiens burial is in Skhul cave, on mount Carmel, Israel, around 120,000 years ago. Neanderthal burials have been found at several sites, including La Chapelle-aux-Saints in France, where the “Old Man” was interred with coloured earth around 60,000 years ago, and Teshik-Tash in Uzbekistan, where a 9-year-old boy was buried circled by ibex horns some 70,000 years ago (American Journal of Physical Anthropology, vol 3, p 151). Dating from around the same time are the graves of 10 individuals found at Shanidar cave in Iraq. Ian Tattersall from the American Museum of Natural History in New York, author of Extinct Humans, notes that one of these burials reveals Neanderthals took care of an injured individual for years before his death, providing “powerful, presumptive evidence for empathy and caring within the social group, and possibly for complex social roles”.

Shanidar is also the location of the famous “flower burial”. The high concentration of pollen from medicinal plants in this grave is sometimes cited as evidence of shamanism and ritualistic funerary practices by Neanderthals. Although this interpretation has been disputed, the case for Neanderthals’ capacity for symbolic thought has recently been bolstered. João Zilhão at the University of Bristol, UK, and Francesco d’Errico at the Institute of Prehistory and Quaternary Geology in Talence, France, found perforated seashells, red and yellow pigments, and shells encrusted with a mixture of several pigments in two caves in Spain, one 60 kilometres from the sea. This, they claim, shows that Neanderthals adorned themselves with symbolic artefacts and, since these date back 50,000 years, before modern humans arrived in the area, they also represent independent Neanderthal innovations (Proceedings of the National Academy of Sciences, vol 107, p 1023).

Admittedly there is no evidence that Neanderthals produced cave paintings, but Zilhão points out that early human cave painting only took off about 20,000 years ago, long after Neanderthals had died out. Instead, he says, Neanderthals may have created more ephemeral artworks, using pigments to decorate their bodies and convey symbolic information about group membership.

Symbolic thought is often associated with another characteristically human trait: language. So is there any evidence that Neanderthals could speak? Ralph Holloway at Columbia University in New York believes so. He has studied hundreds of brain casts from fossilised Neanderthal skulls and found that, even accounting for their big bodies, their brain size is within a few per cent of modern humans and, despite their sloping brows, they had frontal lobes and speech areas like ours.

As well as these physical clues, genetic tests reveal that Neanderthals had a version of a gene called FOXP2 that is associated with language in humans (Current Biology, vol 17, p 1908). Meanwhile, fossils from Kebara cave in Israel show that the Neanderthal hyoid, a U-shaped bone in the neck that anchors key speech muscles, matched ours. “I’m certain that they had language,” says Holloway.

Philip Lieberman, a linguist at Brown University in Providence, Rhode Island, agrees that Neanderthals had speech. However, he argues that before around 50,000 years ago neither Neanderthals nor modern humans could produce the full range of sounds we can today (Expedition, vol 49, p 15). Having studied skulls ranging from 1.6-million-year-old Homo erectus through to 10,000-year-old H. sapiens, Lieberman concludes that neither species was capable of the vowel sounds in “see”, “do” and “ma”. Computer simulations by Robert McCarthy at Florida Atlantic University in Boca Raton support this (newscientist.com/article/dn13672)Speaker.

Given this accruing evidence, Eric Trinkaus at Washington University in St Louis, Missouri, sums up the case for the revisionists: “If you look at the archaeological record of Neanderthals in Europe and modern humans in Africa or the Near East at the same time period, with rare exceptions they are remarkably similar,” he says. “Neanderthals were people, and they probably had the same range of mental abilities we do.”

Case closed? You might think so, but there are still some researchers who disagree with this wholesale reappraisal. “Neanderthals and modern humans separated 500,000 years ago and evolved separately in Europe and Africa. Cumulatively, that represents a million years of evolution,” says Paul Mellars at the University of Cambridge. “It would be staggering if there were not changes in their brains as well as anatomically.” He thinks that cognitive differences between the two species were biologically based and substantial.

The publication in May of the partial Neanderthal genome lends some support to this argument. Although there is less than 1 per cent difference between the genomes of today’s humans and those of Neanderthals, that could equate to mutations in hundreds of genes. Pinpointing these variations has been difficult because the genome’s reconstruction is still incomplete. Even so, Johannes Krause at the University of Tübingen in Germany notes that among those identified so far, several are in genes that underlie brain functioning and cognition, including social and interpersonal skills. “It might be this social aspect where Neanderthals and humans were really different,” he says.

Further support comes from a study by Philipp Gunz and colleagues at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. Their comparison of a virtual reconstruction of the brain case of a Neanderthal newborn and those of modern human infants indicates that the brains were similar at birth, but developed differently during the first year of life, a critical period for cognitive development (Current Biology, vol 21, p R921).

Neanderthals may have other cognitive shortcomings, according to some well-respected researchers. Lewis Binford at Southern Methodist University in University Park, Texas, argues that their lifestyles show little forward planning. Wynn believes that they had less working memory capacity than modern humans, limiting how much information they could process at a given time. “That’s one of the things that could account for their glaring lack of innovation,” he says. Steven Mithen at the University of Reading, UK, grants Neanderthals modern capacities in knowledge of the natural world, manipulating materials and social interaction. However, he thinks they lacked the “cognitive fluidity” and “capacity for metaphor” to link these domains, leaving them unable to produce complex symbolic objects (The Singing Neanderthals, Harvard University Press, 2006). Mellars, too, is not convinced that they were capable of the symbolic thought Zilhão infers from the shell artefacts from Spain. “I think the views of Zilhão are profoundly mistaken. If those are the best things the Neanderthals did in 250,000 years over the whole of Europe, God help them.”

Yet for most of this period early modern humans were not that innovative either. Even Mellars accepts that there are few differences between their accomplishments and those of Neanderthals up until about 50,000 years ago. At this point, however, early modern humans pulled away, undergoing a “big bang” of symbolic activity typified by carved statuettes, elaborate burials, an abundance of personal decorations and, eventually, elaborate cave paintings. Mellars argues that by the time modern humans entered Europe, they had better technology, better social organisation and better brains. “The Neanderthals were playing against a better team,” he says.

Anthropologist Richard Klein at Stanford University in California agrees. Like Mellars, he thinks significant genetic changes underlie the cognitive and symbolic flowering that occurs in modern humans. “Some people think it’s almost racist to suggest that Neanderthals or earlier humans differed from us genetically,” he says. “I’ve been accused of Neanderthal bashing, as if I were trying to keep them out of Harvard.” Yet Klein is standing his ground. “Those genes which are uniquely modern could help explain why Neanderthals aren’t around anymore.”

That, for traditionalists, is the crux of this debate: Neanderthals became extinct, while we are still very much extant. But here the revisionists seem to have the last laugh. Neanderthals may no longer be with us in the flesh, but their genes live on, accounting for as much as 4 per cent of the genome of anyone of non-African ancestry. That is the equivalent of a great-great-great grandparent (see “What DNA can say”).

This is even more remarkable given the size of Neanderthal populations: the limited variation in their mitochondrial DNA indicates a sustained breeding population of just 3500 individuals (newscientist.com/article/dn17477). As Zilhão points out, the genetic reservoir of modern humans in Africa was many times greater than that of the Neanderthals. “What happens when you mix one litre of white paint with 100 litres of black paint? You get 101 litres of black paint,” he says. “That’s just what the geneticists found.”
What DNA can say

In May 2010, a team led by Richard Green from the University of California, Santa Cruz, and Svante Pääbo from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, reported an astonishing feat. From fossilised bone fragments of three Neanderthals who lived 40,000 years ago in what is now Croatia, they reassembled 60 per cent of the Neanderthal genome and made the first detailed genetic comparison of Neanderthals and modern humans (Science, vol 328, p 710).

Extrapolating from the available sequences, the team estimate that Neanderthals and modern humans are almost as closely related as any two living humans: you might share 99.9 per cent of your DNA with a randomly selected human, and 99.8 per cent with a Neanderthal. This reflects our shared common ancestors, from whom we split around 500,000 years ago.

Two species or one?

The biggest surprise, however, was that people of non-African ancestry are more similar to Neanderthals than Africans are, leading the researchers to conclude that between 1 and 4 per cent of the DNA of all non-African people comes directly from Neanderthals. The only way that non-Africans worldwide could have acquired this dose of Neanderthal DNA is if modern humans leaving Africa mated with Neanderthals before colonising the rest of the world, something the researchers think happened in the Middle East about 45,000 years ago. This was unexpected, as previous studies of Neanderthal mitochondrial and Y-chromosome DNA showed no signs of mating with modern humans.

The DNA that sets us apart from Neanderthals is also interesting. The team discovered 78 genes and 200 longer stretches of genome in which modern humans all share the same DNA sequences but Neanderthals don’t. These represent mutations that occurred in the human line after it split from our common ancestor. The sequences include genes affecting sensory functioning, cognition, social interaction, metabolism and immunity. “Exactly how our brain physiology and cognition are different we don’t understand yet,” says Green. “But now we know where to look.”

No one ever expected there to be a single gene separating Neanderthals and us, yet the researchers were intrigued by RUNX2. A mutation in RUNX2 causes a suite of skeletal changes, including the brow ridges and bell-shaped chest typical of Neanderthals. “It’s extremely tantalising,” says Pääbo. “It might be a gene that actually reflects what you see in the archaeological record.”

Some had hoped the genome comparison might resolve the 150-year-old debate over whether Neanderthals and humans belong to the same species. After all, one definition of distinct species is that they cannot mate and produce fertile offspring. Pääbo won’t be drawn in. “I think that when we come to such closely related groups as Neanderthals and humans, these definitions contribute more confusion than clarity,” he says. “It just makes people excited for no reason.”

Roads to extinction

Everyone, it seems, has a different idea about why Neanderthals became extinct. Those who see them as an inferior species suspect that smarter, more talkative, more social and adaptable early modern humans were to blame, outcompeting Neanderthals in terms of resource use, organisation and reproductive success, if not direct confrontation. Meanwhile, those who believe that Neanderthals were just as smart as early humans typically look to climate change, natural catastrophes and cumulative cultural differences to explain the extinction. In The Humans Who Went Extinct (Oxford University Press, 2009), for example, Clive Finlayson argues that the Neanderthals’ stocky build and close-in hunting style limited them to a shrinking environment and made them increasingly vulnerable to a deteriorating climate, inbreeding, disease and competition. Chris Stringer at the Natural History Museum in London thinks the last Neanderthals were just unlucky. “It was one of the most unstable periods in terms of Earth’s climate. They had to cope with those changes and they had a competing species alongside them,” he says. “It was a kind of double whammy.”

Robert Adler is a writer based in California and Mexico