November 2003 issue/ Scientific American
Stunning finds in the Republic of Georgia upend long-standing ideas
about the first hominids to journey out of Africa.
By Kate Wong
With a brain half the size of a modern one and a brow reminiscent of
Homo habilis, this hominid is one of the most primitive members of our
genus on record. Paleoartist John Gurche reconstructed this 1.75-
million-year-old explorer from a nearly complete teenage H. erectus
skull and associated mandible found in Dmanisi in the Republic of
Georgia. The background figures derive from two partial crania recovered
at the site.
Overview / The First Colonizers
We shall not cease from exploration
And the end of all our exploring
Will be to arrive where we started
And know the place for the first time.
--T. S. Eliot, Four Quartets: "Little Gidding"
In an age of spacecraft and deep-sea submersibles, we take it for
granted that humans are intrepid explorers. Yet from an evolutionary
perspective, the propensity to colonize is one of the distinguishing
characteristics of our kind: no other primate has ever ranged so far and
wide. Humans have not always been such cosmopolitan creatures, however.
For most of the seven million years or so over which hominids have been
evolving, they remained within the confines of their birthplace, Africa.
But at some point, our ancestors began pushing out of the motherland,
marking the start of a new chapter in our family history.
It was, until recently, a chapter the fossil record had kept rather
hidden from view. Based on the available evidence--a handful of human
fossils from sites in China and Java--most paleoanthropologists
concluded that the first intercontinental traveling was undertaken by an
early member of our genus known as Homo erectus starting little more
than a million years ago. Long of limb and large of brain, H. erectus
had just the sort of stride and smarts befitting a trailblazer. Earlier
hominids, H. habilis and the australopithecines among them, were mostly
small-bodied, small-brained creatures, not much bigger than a modern
chimpanzee. The H. erectus build, in contrast, presaged modern human
body proportions.
Curiously, though, the first representatives of H. erectus in Africa, a
group sometimes referred to as H. ergaster, had emerged as early as 1.9
million years ago. Why the lengthy departure delay? In explanation,
researchers proposed that it was not until the advent of hand axes and
other symmetrically shaped, standardized stone tools (a sophisticated
technological culture known as the Acheulean) that H. erectus could
penetrate the northern latitudes. Exactly what, if anything, these
implements could accomplish that the simple Oldowan flakes, choppers and
scrapers that preceded them could not is unknown, although perhaps they
conferred a better means of butchering. In any event, the oldest
accepted traces of humans outside Africa were Acheulean stone tools from
a site called 'Ubeidiya in Israel.
Brawny, brainy, armed with cutting-edge technology--this was the hominid
hero Hollywood would have cast in the role, a picture-perfect pioneer.
Too perfect, it turns out. Over the past few years, researchers working
at a site called Dmanisi in the Republic of Georgia have unearthed a
trove of spectacularly well preserved human fossils, stone tools and
animal remains dated to around 1.75 million years ago--nearly half a
million years older than the 'Ubeidiya remains. It is by
paleoanthropological standards an embarrassment of riches. No other
early Homo site in the world has yielded such a bounty of bones,
presenting scientists with an unprecedented opportunity to peer into the
life and times of our hominid forebears. The discoveries have already
proved revolutionary: the Georgian hominids are far more primitive in
both anatomy and technology than expected, leaving experts wondering not
only why early humans first ventured out of Africa but how.
AdvertisementImage: GOURAM TSIBAKHASHVILI (fossils); CHRISTIAN SIDOR
(New York College of Osteopathic Medicine (modern skull)
Sidebar: Skull SurprisesA Dubious Debut
As the crow flies, the sleepy modern-day village of Dmanisi lies some 85
kilometers southwest of the Georgian capital of Tbilisi and 20
kilometers north of the country's border with Armenia, nestled in the
lower Caucasus Mountains. During the Middle Ages, Dmanisi was one of the
most prominent cities of the day and an important stop along the old
Silk Road. The region has thus long intrigued archaeologists, who have
been excavating the crumbling ruins of a medieval citadel there since
the 1930s. The first hint that the site might also have a deeper
significance came in 1983, when paleontologist Abesalom Vekua of the
Georgian Academy of Sciences discovered in one of the grain storage pits
the remains of a long-extinct rhinoceros. The holes dug by the citadel's
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
To Search in the Gambia-L archives, go to: http://maelstrom.stjohns.edu/CGI/wa.exe?S1=gambia-l
To contact the List Management, please send an e-mail to:
[log in to unmask]
To unsubscribe/subscribe or view archives of postings, go to the Gambia-L Web interface
at: http://maelstrom.stjohns.edu/archives/gambia-l.html
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|