Early
Homo sapiens, known from fossils found at Omo and Herto in Ethiopia, began
making stone tools in the Nile Valley of Egypt some 150,000 years ago. Previous
studies have traced their path out of Africa through Sinai to the Levant. New
research reveals a second, more southerly route through Arabia, where modern
human populations lingered for some 50,000 years before migrating north to the
Levant. There they interbred with Neanderthals—and perhaps borrowed some of
their tool-making techniques.
Stylistic
and manufacturing similarities, the archaeologists say, connect the dots between
tools made first in the Nile Valley of Egypt, then in the Arabian Peninsula,
and, finally, in Israel. Those tools became progressively smaller and more
sophisticated, similar to the evolution of mobile phones today.
"Archaeologists have always focused so
much on 'out of Africa and into the Middle East' that we've missed an entire
chapter of the human expansion in Arabia," says archaeologist Jeffrey Rose
of the Ronin Institute, based in New Jersey, co-author of a new report
published this month in Quartär.
Our
species' birthplace was in Africa about 200,000 years ago, according to fossils
from sites such as Omo and Herto Bouri in Ethiopia. While these fossils look
modern, however, the populations they represent didn't begin to act fully
modern until later.
A
tool kit known as the Emiran, dated to almost 50,000 years ago, defines the
transition between archaic and modern human behavior—at least as far as
tool-making goes. But since the discovery of the first Emiran tools—points,
blades, and scrapers found in a cave near the Sea of Galilee in Israel in
1951—archaeologists have puzzled over where this more advanced way of making
tools began.
"The Emiran is the bridge
technology," says Rose, who is also a National Geographic Emerging
Explorer. "But where did these guys come from?"
Out
of ... Arabia ?
Working
with his former thesis adviser, archaeologist Anthony Marks of Southern
Methodist University in Dallas, Rose studied all of the stone tools he could
get his hands on in Arabia, northeastern Africa, and the Middle East.
In
their new report, the pair says the evolution of stone tools in the region
began in the Nile Valley of Egypt 150,000 to 130,000 years ago. These Nilotic
hunter-gatherers in Egypt made Nubian tools by chipping away edges of a stone
core in a systematic way to produce a single triangular point, which could be
attached to a spear, for example.
While
other researchers have proposed that the Egyptian Nubian toolmakers moved
rapidly to the Middle East, where they invented the Emiran, Rose and Marks
argue that they went to Arabia first—and that it was their Arabian descendants
who would later develop the Emiran.
In
their report, the researchers describe two different types of tool kits that
appear to be offshoots of the Egyptian Nubian in Arabia and were developed
110,000 to 50,000 years ago: the Dhofar Nubian and the Mudayyan industries of
the Nejd Plateau of Oman.
From
the Dhofar Nubian to the Mudayyan, stone points get smaller and more elongated
over time, becoming more similar to the Emiran tools, perhaps because the
modern humans were using them as projectile points to hunt smaller,
quick-moving animals as the climate got drier and finding food became more
challenging. The people who made the Mudayyan tools in Oman were most likely hunting
small animals like lizards and rodents, says Rose.
Picture
of a Nubian Levallois core and point refit back together
A
Nubian stone core (bottom right) and point (bottom left) are fit back together
(top). Early modern humans in Egypt around produced such triangular points by
chipping away the edges of a core. Later modern humans in the Middle East used
a more efficient technique to make multiple points from a single core.
In
their scenario, Rose and Marks suggest that the Arabian toolmakers pushed north
into the Middle East when the climate changed dramatically in Arabia about
75,000 years ago. At that time, Arabia was beset by drought, which parched
lakes and underground streams and converted grasslands into sand dunes.
By
contrast, the climate began to grow wetter and more humid in the Middle East
60,000 years ago, drawing animals—and hunters—northward, according to the
scenario proposed by Rose and Marks. There, modern humans made a major
breakthrough: Instead of producing just one tool from a single stone by
striking the core in one direction, from top to bottom, as their Nubian
ancestors did, they learned how to strike many elongated blades from the top
and the bottom of a single core, in succession—a telltale feature of the Emiran
and subsequent Upper Paleolithic industries.
But
in a surprising twist, the researchers also propose that the modern humans who
made the Emiran were influenced by archaic people, possibly Neanderthals, who
left behind fossils in Israel some 70,000 to 50,000 years ago, as well as more
primitive tools, called Mousterian. The scientists say the Emiran tools are
made in the same systematic manner as Egyptian Nubian tools, but closely
resemble the local Mousterian tools.
The
timing fits with genetic studies that suggest that modern humans interbred with
Neanderthals when they arrived in the Middle East. A 55,000-year-old modern
human skull from Manot Cave in Israel, reported last month, has provided new
evidence that the moderns were there at the same time as Neanderthals.
Not
everyone agrees that the Emiran hunter-gatherers' tool-making was influenced by
their Neanderthal neighbors. The Emiran "has nothing to do with
Neanderthals," says Harvard University archaeologist Ofer Bar-Yosef, who
proposed a decade ago that the Emiran was made by Egyptian Nubians when they
moved directly to the Middle East.
Regardless
of who influenced the Emiran toolmakers, the long and winding path that led to
modern tools may have taken a lengthy detour through Arabia.
"The Arabian region was not just the
route to somewhere else, which it has often been considered in various
dispersal scenarios," says paleoanthropologist Chris Stringer of the
Natural History Museum in London. "It was at times a significant location
in its own right for early modern humans and perhaps for Neanderthals too."
هیچ نظری موجود نیست:
ارسال یک نظر