April 2018^ DISCOVER^41HENSHILWOOD/GRETHE MOELL PEDERSEN
have territories of 12 to 25 miles in diameter, and
researchers believe early human groups had similar
ranges. The presence of exotic objects from well
beyond that range implies different groups were
interacting in some way.
“Whether you got it by trade or got it yourself,
you had to make contact with people from another
group,” Brooks says. At more than 300,000 years
old, Olorgesailie is significant because this kind of
interaction is a hallmark of modern humans that
researchers previously thought developed around
100,000 years ago.
“We see this as the first evidence of a social
network,” says Brooks. “The picture of modern
human behavior was being put together much
earlier than we thought.”FEED YOUR HEAD
Ochre reveals details about our ancestors’
behavior, but could it have played a more active
role in our evolution?
Marine ecologist Carlos
Duarte of Saudi Arabia’s
Abdullah University
thinks so. The idea came
to him when preparing
to give a talk on the role
of the ocean in our past
and future.
“I was aware of research
arguing that the use of
the marine food web had
played a significant role
in brain evolution, and
expansion, through the
supply of omega-3 fatty
acids,” Duarte says via email while traveling.
“However, when I searched for new research on
evidence of use of marine food by early humans,
I noticed that over and over, the traces of it,
shells, were accompanied by ochre. This link is so
prevalent that it could not be a coincidence.”
Indeed, different types of shells have been
found with ochre at numerous prehistoric sites
around the world. Duarte dug deeper into the
archaeological record, eventually publishing a
provocative commentary in Trends in Ecology &
Evolution. The ingestion of red ochre, suggests
Duarte, combined with consumption of seafood,
boosted early humans’ supply of docosahexaenoic
acid (DHA) and iodine as well as, potentially,
iron and other nutrients essential for brain
development.
Duarte believes the advantage conferred
was particularly valuable for pregnant women:
Fortifying a diet with iron from ochre might staveoff anemia, a common problem in pregnancy.
Combined with seafood, it might also result
in a healthier baby. A significant amount of
brain development occurs prenatally, when the
developing fetus would have received DHA,
iodine and other essential nutrients.
The key, Duarte says, is the combination of
nutrient-rich seafood and red ochre — the iron
in other types of ochre, or in red ochre ingested
without protein supplied by the seafood, cannot
be absorbed by the body.
But Stanley Ambrose, a paleoanthropologist at
the University of Illinois at Urbana-Champaign,
dismisses Duarte’s idea. In addition to studying
ochre use in the Middle Stone Age, Ambrose
is a leading expert in reconstructing the diet of
Paleolithic people through chemical analysis of
their remains.
“There were plenty of big-brained hominins
running around without any access to sea life,”
Ambrose says. “Ochre gets smeared on a lot of
things, but he’s made a false
connection. ... They’re good
ideas, but you have to put
them in context.”
Other researchers are
keeping a more open
mind. “It wasn’t necessary
for them to eat ochre,”
says Hodgskiss. “But
it’s plausible.”
In fact, geophagy, or
intentionally consuming
dirt, has been documented
in multiple historical and
present-day cultures, many
of which ingest specific
soils medicinally to prevent
diarrhea or increase
iron intake.
“People certainly engage in geophagy all over
the world, especially while pregnant,” Zipkin says.
“But I think it’s very, very hard to demonstrate
in any meaningful way consumption in the
archaeological record.”
While Duarte’s idea has yet to gain traction
in the paleoanthropological world, it’s just
one of several new directions ochre research is
taking. Together with elemental fingerprinting,
experimental archaeology and the discovery of
new sites, it’s likely the story of humans and ochre
has many more chapters to go.
“Fifteen years ago, no one did this work,” Zipkin
says. “There are more things now that you can do
with ochre than we ever thought possible.”^ DGemma Tarlach is senior editor at Discover.Ingesting seafood
and ochre may have
given our ancestors a
nutritional advantage.