56 DISCOVERMAGAZINE.COM
AQUAPIX/SHUTTERSTOCKFor decades, textbooks taught that humans left our ancestral
African homeland and spread across the world via the land-
masses we know today, reaching Australia less than 50,000 years
ago and the Americas a mere 13,500 years ago. But there’s a
continent-sized gap in our knowledge about our collective past
that scientists are only now starting to fill in.
From the North Sea to the island-dotted tropics between Asia
and Australia, from the frigid waters of the Bering Strait to the
sunny Arabian Peninsula, now-submerged coastal landscapes
were exposed and accessible to our ancestors at multiple times
in prehistory, including key periods of human expansion across
the globe. The square mileage of these areas now under the seas
is equal to that of modern North America.
“My own view is that there are certainly sites out there,” says
University of York archaeologist Geoff Bailey. “Some of the
areas [that would have been] most attractive to humans are
now underwater.”
Long out of scientists’ reach, these submerged landscapes,
which some researchers collectively call Aquaterra, are finally
emerging from beneath the waves — at least figuratively. Thanks
to cutting-edge technologies and increasing evidence that the old
models of early human dispersal no longer make sense, several
projects are underway to reconstruct these ancient worlds and
search for evidence that will likely rewrite the human story.
SEA CHANGE
The first members of the genus Homo emerged at roughly the
dawn of the Pleistocene, which began about 2.6 million years ago
and ended with the final drips of the last great glacial melt, about
12,000 years ago. It is, essentially, the epoch of human evolution.
By its end, only one species of human remained — us — and we
had settled and thrived on every continent except Antarctica.
For 95 percent of the time that humans have existed,
sea levels have been lower than they are now, usually by about
130 feet. At their lowest, they were about 400 feet lower, globally,
than they are today.
These dramatic shifts in sea level occurred during the
Pleistocene, during which the world seesawed between multiple
glacial maxima, when much of the world’s water was locked up in
massive ice sheets, and interglacial periods, when the ice melted
and inundated low-lying continental shelf edges.
Many researchers refer to these now-flooded lowlands by their
regional names, such as Beringia, which once connected Siberia
with Alaska. But retired University of Kansas geographer Jerome
Dobson has led a crusade for two decades to give these lost lands
a single name, Aquaterra, to underscore their significance to the
human story.
Just as today’s human populations cluster along coastlines —
nearly half of us globally live within an hour of a coast — our
ancestors likely did as well. These lost regions are not merely
stretches of continental shelf now underwater, but rather
resource-rich ecosystems and corridors once used for exploration
by early humans.
“If you look at the factors that drove our evolution, a lot
of them were coastal,” Dobson says. For example, the richest
sources of the element iodine — essential for our thyroids to
function — are fish, seaweed and shellfish. “Iodine is a coastal
resource,” he says. “We have to have it to survive. We’re dependent
on it.”
Hunters and foragers on the coasts would have enjoyed the best
of both worlds, terrestrial and marine, with access to fresh water,
land animals and plants as well as shellfish, seaweed, seabirds
and fish.
The appeal of coastal living is not just limited to humans, either.
“If you look at ecological data for mammals, both herbivores
and carnivores occur in greater densities in coastal regions,”
says Bailey.
He adds that glacial maxima, when ice sheets were expansive andWhatever you learned in school
about how our species spread
across the planet is wrong.