Archaeologists, historians, linguists, nutritionists come together in
symposium to explore Earth’s past
By Alvin Powell
Harvard News Office
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.
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