Bone wars

Are we not who we thought we were? A boy's 25,000-year-old remains call into question our very roots and kick up a nasty battle among scientists.


Juno Gregory
August 27, 1999 8:00PM (UTC)

Under an overhanging shelter of limestone, in an area that would later become known as Abrigo do Lagar Velho in the Portuguese valley of Lapedo, a grieving family prepared a grave for a 4-year-old boy, whose small but sturdy body lay wrapped in a shroud of animal skins nearby. A pierced shell hung on a leather thread around his neck. More shells and pieces of animal bones were set up in a rough oval around the area where the child would be laid to rest.

Twenty-five thousand years later, in December 1998, the discovery of the child's fossilized remains launched another of the nasty academic tumults so common in the field of paleoanthropology. This one, however, was more bitter than usual, and more visible, because it was not confined to the stately rhythms and limited circulation of journal publication. This dispute was taken to the Web, and, as one observer put it, it quickly developed into "excursions and alarums all over the Internet."

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The "battle of the bones" began when the child's skeleton was examined by an international team headed by noted Neanderthal expert Erik Trinkaus of Washington University in St. Louis, who was surprised to discover an unusual combination of features in the bones. The Lagar Velho child seemed to have characteristics of both Neanderthals and modern humans, and to Trinkaus that meant that the child was an "intermediate" form, a kind of "missing link" between what he sees as two different species of humans, the Neanderthal and the so-called Cro-Magnon. To a scientific community still debating whether Neanderthals contributed to our modern line, Trinkaus' hypothesis -- reported in the European press as "The 'Clan of the Cave Bear' Love Child" -- was a bombshell.

Trinkaus and his team, which included Joco Zilhco, director of the Portuguese Institute of Antiquities, published the details of the skeleton and the team's Neanderthal-modern "admixture" hypothesis in the June 22 issue of the Proceedings of the National Academy of Sciences. The issue also featured a commentary by Ian Tattersall of the American Museum of Natural History and Jeffrey Schwartz of the University of Pittsburgh which dismissed the Trinkaus team's conclusions. And that's when the real trouble began.

Trinkaus later claimed that the commentary implied that he and his colleagues "didn't know their ass from their elbow." Most observers say that the Tattersall and Schwartz paper was polite and discreetly worded, but another anthropologist familiar with the players thinks that Trinkaus' fierce reaction to it was nevertheless inevitable: "Erik," he said, "has never taken criticism well."

PNAS does not publish responses to commentaries, so the furious Trinkaus and Zilhco resorted to the Internet. They posted a lengthy and venomous "correction" on the Instituto Portugues de Arqueologia Web site on June 24, in the form of a scathing treatise, which they also e-mailed to colleagues worldwide.

The return broadside on the IPA Web site was merciless. It called the Tattersall and Schwartz commentary "inappropriate, inaccurate and unethical," and "replete with mis-information ... mis-quotes ... poor logic, general incompetence ... [and] anatomical ignorance." Trinkaus and Zilhco expressed particular outrage over what they considered a breach of professional ethics: A large part of the commentary was apparently based on observations of slides shown during an informal oral presentation at a scientific meeting this spring. While acknowledging that they had some legitimate grievances, another paleoanthropologist described Trinkaus and Zilhco's vituperative Internet statement as "the nastiest, meanest criticism I have seen -- ever. And this is in a field that is noted for arguing and disputes."

At issue, beyond the personal reputations of the players -- a factor not to be taken lightly in a field where professional regard often translates directly into book contracts -- is a complicated mix of rival theories on human evolution in Europe. Competing paradigms in the sciences are nothing new, but when human origins are the issue, each piece of evidence can resonate with uncomfortable implications. "Neanderthals," says Kharlena Ramanan, who maintains a Web site on the subject, "are the ancestors nobody wants."

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Most paleoanthropologists agree that the common ancestor of both modern humans and Neanderthals arose in Africa several million years ago, and that this common ancestor's descendants spread widely over the Earth, evolving as they went. In general, hominids in tropical zones of the world, such as sub-Saharan Africa, tended to evolve toward a taller, more gracile form, and those venturing into colder areas moved toward a more compact, shorter and heavier-boned shape, which would expose less surface area and retain body heat better. Neanderthals, in coping with Ice Age Europe, evolved toward that heavy-boned "arctic" profile.

The question is, how far did Neanderthals drift from the African original? Some paleoanthropologists believe that Neanderthals became so distinct as a group that they were a totally separate species of hominid. This theory contends that when another wave of dispersal from Africa occurred -- supposedly bringing members of a highly successful and adaptable African line into the Neanderthals' European stomping grounds about 35,000 years ago -- the Neanderthals were doomed.

Over approximately 10,000 years of the fossil record, anatomically distinct Neanderthal skeletons disappeared and -- more or less concurrently, depending on who you ask -- more slender and "tropical" skeletons emerged. These so-called Cro-Magnon, or anatomically modern humans, were associated with increasingly sophisticated cultural artifacts and tools.

To many anthropologists, this pattern suggested that "Out of Africa" moderns simply replaced the Neanderthals. Some of the replacement scenarios suggest a Paleolithic version of Attila the Hun, in which invading Cro-Magnons ruthlessly exterminated fleeing Neanderthals. Others in the replacement school believe that the Neanderthals might have been infected with new Cro-Magnon diseases. By far the most common theory, however, is that anatomically modern humans simply outclassed the Neanderthals -- mentally, culturally and technologically -- in competition for survival resources.

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All of these replacement theories assume that the Neanderthals were merely an unsuccessful branch on the family tree, Mother Nature's failed experiment. Any similarities that we can see between ourselves and Neanderthals, these scientists argue, are only the result of our both having descended from that much older common African ancestor.

However, David W. Frayer of the University of Kansas, along with Milford Wolpoff and C. Loring Brace of the University of Michigan, has been arguing for at least a decade that the apparent succession in the fossil record is deceptive. Frayer maintains that there really was no abrupt shift between separate populations, but a transition within Neanderthals over time, which eventually led to our own body type. "There undoubtedly were population movements into Europe bringing in new genes," he says, "but there was no rapid replacement."

In Trinkaus' version of what happened in Europe, the two distinct groups coexisted, then came together, interbred and thus merged genetically. The Lagar Velho child, Trinkaus and his team contend, is an example of an "intermediate" form between two distinct types of humans, and thus constitutes proof of the "genetic admixture" hypothesis.

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Most of the child's skull was destroyed by earth-moving equipment which inadvertently uncovered his burial site during the building of a farm road. The loss of the skull was especially unfortunate given that most of the distinguishing Neanderthal characteristics on which scientists can agree are found in the skull. The Trinkaus team's argument was therefore forced to depend heavily on the very robust and "arctic" characteristics of the child's arm and leg bones, which align it with the Neanderthals, and the unusual combination of a retreating angle at the front of the jaw (a common feature of Neanderthals) with a sharply pointed chin bone, a distinguishing feature of moderns. Most of the rest of the child's characteristics, like the proportions of his teeth, were arguably modern, so replacement theorists like Tattersall and Schwartz found the Trinkaus team's hypothesis unconvincing. They tend to think that the fossil is merely a particularly short and sturdy "modern" specimen.

The child is indeed short and sturdy for a modern: The long bone proportions and the angle of the retreating jaw are more than two standard deviations from the mean of anatomically modern humans. Though possible, it's statistically unlikely that a given skeleton will demonstrate characteristics which are at the tail-end of the bell curve for its group. It's even more improbable that the child was the result of a single unusual Neanderthal-modern mating, ` la "Clan of the Cave Bear." It's far more likely that the child's characteristics were common in the local population of his time.

While he allows that Trinkaus' "admixture" hypothesis is "certainly still plausible," Chris Stringer, professor of paleontology at the Natural History Museum in London, thinks there might be another explanation for the boy's apparently "arctic" body shape: The population in the area may have adapted to a shift in the local climate. "There is evidence that the polar front was diverted down to the Portuguese coast about 2,000 to 3,000 years before this boy was alive," says Stringer. "At that time, the average temperature in the region could have fallen by at least seven degrees and there may have been icebergs floating off the north Portuguese coast."

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Tattersall and Schwartz have spent considerable professional energy annotating and distinguishing different forms, or morphologies, in hominid evolution. Schwartz assumes that human beings are not a special case in biological history. "If you let morphology do the talking," he says, "you are impressed by the record's diversity." The human fossil evidence, he contends, reflects a pattern common in other animals' family trees, characterized by numerous deadfalls and withered branches along the way. He thinks it is absurd to assume that virtually all the ancient hominid lines converged into our own. "That's just not the way nature works," he says, "and we are part of nature."

Tattersall distributed a pointedly brief reply to Trinkaus and Zilhco's vitriolic screed, which he described as "inappropriate" and "defamatory." It was, he says, "a grave abuse of the privilege of unfettered communication that is conferred by the Internet," and he was "saddened" that Trinkaus and Zilhco chose to portray him and Schwartz as "self-deluding and intellectually dishonest incompetents."

When asked why he and Tattersall had not made a more substantive answer to Trinkaus and Zilhco's pages of detailed charges, Schwartz said he considers it pointless to get into a "pissing contest" with Trinkaus. In any case, he says, he and Tattersall expect to be vindicated by new data, particularly on Neanderthal DNA, which should accumulate rapidly over the next few years.

Trinkaus, for his part, considers the matter closed. "Our 'correction' on the IPA Web site was intended simply as that," he says, "a correction to an abysmal piece of scholarship, in the hope that it would minimize the scientific damage caused by the commentary."

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Ultimately, however, both sides of this disagreement are battling over a false distinction, says Loring Brace: "To Ian, the Lagar Velho fossil is just a robust 'modern,' while to Erik that robustness has to indicate a mixture between a set vision of the modern on the one side and the Neanderthal on the other. It does not occur to either one that this is just what you would expect at that time if the robust earlier Neanderthals had evolved ... until they were modern in form. That is the evolutionary perspective that is missing in both their approaches."

Thousands of years before the scientists started arguing about their son, the family of the Lagar Velho child transferred his shrouded body to its prepared place. They sprinkled dark red earth over and around him, because the red ochre symbolized something to them -- their life's blood, perhaps. Then they heaped in more soil and covered him with rocks to keep wild animals from scavenging in the grave. He would lie undisturbed for 25 millennia, until his civilized descendants unearthed him and began snapping and snarling over the meaning of his remains.


Juno Gregory

Juno Gregory is a freelance writer and book doctor who lives in Charleston, South Carolina.

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