Of Neanderthals and dairy farmers

Harvard Archaeology Professor Noreen Tuross sought to rehabilitate the image of Neanderthals as meat-eating brutes last week, presenting evidence that, though they almost certainly ate red meat, Neanderthal diets also consisted of other foods — like escargot.

Evidence from Neanderthal bones collected from the Shanidar cave in Northern Iraq decades ago and analyzed recently by Tuross indicate that at least that particular Neanderthal was not a heavy carnivore. Neanderthals, she suggested, had a varied diet that included meat, but that was not solely or even largely made up of it. One possible alternative food was found in abundance in the cave, she said: land snails.

“This was not a heavy meat-eater,” Tuross said. “So what else can they be eating? I think the answer is escargot.”

Tuross, the Landon T. Clay Professor of Scientific Archaeology, was just one expert in disciplines ranging from anthropology to history to genetics attending a day-long symposium Friday (Dec. 5) that aimed to bridge divides between traditional fields in order to shed more light on the human past.

The event, “The Science of the Human Past,” was sponsored by the Harvard Provost’s Office and the Broad Institute of MIT and Harvard, and was organized by the Initiative for the Science of the Human Past at Harvard University.

Michael McCormick, the Francis Goelet Professor of Medieval History, said the symposium grew out of a series of workshops he organized three years ago after he received the Mellon Distinguished Achievement Award. McCormick said he decided to use the award money to bring together scientists and humanists who would not otherwise meet, to see if they could learn from one another’s data and methods. The meetings were so successful that McCormick and several colleagues, including Nick Patterson, David Reich, and Stuart Shieber, organized the symposium. They had expected about 50 people to attend, but the event drew more than 170.

“It’s really been remarkable,” McCormick said.

In addition to Tuross’ talk, the agenda included presentations on the Neanderthal Genome Project, the impact of sex-based evolutionary forces on the human genome, humans and the extinction of the megafauna, mathematical modeling of contact between linguistic groups, and the origins of dairy farming.

Tuross praised the effort to unify scholars in different disciplines who are seeking answers to similar questions.

Tuross’ attempt to show the Neanderthal’s dietary diversity comes on the heels of studies that examined the concentration of a type of nitrogen atom that increases in animals as they feed up the food chain. One study showed that Neanderthals living in Vindija Cave in Croatia had higher concentrations of this atom than even top predators, leading researchers to conclude that Neanderthals were heavy meat eaters.

Tuross questioned that conclusion, however, saying that scientists don’t know why that particular nitrogen isotope concentrates in predators, making it possible that other mechanisms are at work. In addition, she said, studies of Neanderthals on Gibraltar showed they had a varied diet, as do modern humans, who are among the most omnivorous animals on earth.

“Humans are promiscuous in our omnivory. We can eat almost anything and do eat almost anything, in prodigious quantities,” Tuross said.

The evolutionary forces that split humans from Neanderthals hundreds of thousands of years ago didn’t go away after the break. Mark Thomas, of University College, London, presented evidence about one of the strongest forces that has driven human evolution in Europe over the past 20,000 years: milk.

Thomas’ research showed that a gene variant for “lactase persistence” (LP) that allows humans to digest milk into adulthood — uncommon in most adult animals and in many human societies — swept across Europe sometime in the last 20,000 years.

To spread so rapidly, Thomas said, the gene must have conveyed an extraordinary survival advantage to those possessing it. Though science has not yet identified the specific advantages at play in early Europe, there are several potential candidates. Among them is that milk provides a ready source of calories, protein, calcium, and fat, particularly during the winter or during crop boom-and-bust cycles. It also provides an uncontaminated source of fluids, perhaps lessening illness and parasitic infections; and obtaining it may be a more economical use of lands than farming.

“In Europeans, this is probably the most strongly selected part of the genome in the last 20,000 years,” Thomas said.

Thomas found that the gene variant coincided well with the rise of animal domestication, indicating that humans became dairy farmers almost as soon as they began to keep animals.

To track the gene’s spread across Europe, Thomas designed a computer model that took into account both archaeological and genetic data. He then ran multiple simulations, randomly changing other variables and looking for patterns that matched what is known today.

The closest matches pegged the rise of milk-drinking Europeans to about 7,400 years ago in central Europe. The spread matched the known rapid spread of Europe’s first farmers, the Linearbandkeramik culture.

“The spread of the LP variation was shaped by selection and by an underlying demographic process, the spread of farming,” Thomas said.

alvin_powell@harvard.edu