November-December 1996
November-December 1996
Roy Larick and Russell L. Ciochon
Western Temperate Habitats
If early Homo was able to disperse early and quickly
across subtropical East Asia, why does it seem to arrive later in West Asia
and yet later in Europe? For West Asia, the sites of 'Ubeidiya in the western
Jordan Rift of Israel, and Dmanisi, southeast of Tblisi, Georgia, provide
the most information on early occupation. 'Ubeidiya's 150 vertical meters
of geological infill appear to have been deposited over a short period.
The assemblage of animal fossils in the stratigraphic column suggests that
much of the deposit dates to nearly 1.4 mya. The lower archaeological levels
contain a range of stone flakes and tools, some having the standardized
forms associated with contemporary assemblages in East Africa, but there
are no biface tools. The upper levels, not greatly different in age, clearly
have these Acheulian tools. As only a few isolated human teeth have been
recovered from the site--only one in geological context-the hominids responsible
for the stone tools remains unknown. Ofer Bar-Yosef of Harvard University
interprets the sequence as the result of two separate hominid occupations
within a relatively short time. Both groups shared an advanced core-tool
technology; one group used biface tools, the other did not.
The deposits at Dmanisi were first excavated in the 1980s
for their faunal remains. Later, an assemblage of simple flake and core
tools was found and, finally, in 1991, a complete jaw of Homo erectus.
The age of the hominid and the artifacts is debatable. The enveloping sediments
have a paleomagnetic interpretation of about 1.8 mya and a potassium-argon
determination on the underlying lava flow corroborates with 1.8 mya. Nevertheless,
the hominid fossils and tools appear to lie in pockets having a younger
paleomagnetic reading. A conservative biostratigraphic estimate for the
remains is 1.4 mya, nearly identical with the dating of 'Ubeidiya. Combining
the information from these two sites suggests that the Levant provided a
corridor northward from Egypt and Saudi Arabia into Europe and northwestern
Asia. Possibly, the eastern Mediterranean region has remained too rugged
to support a Pliocene population of Homo, no matter how open the
habitat. One other very enigmatic site plays into the timing of hominid
dispersals to the Middle East. In the western Jordan Rift, the site of Erq-el-Ahmar
has yielded a few probable core tools in a geological formation that antedates
that of 'Ubeidiya. A paleomagnetic analysis indicates an age of about 1.8
mya, but some doubt remains about the date and the artifacts themselves.
As for Europe, it is fairly clear that mountain ranges, large watercourses
and generally rigorous climates inhibited any significant early dispersal.
It is certain, however, that a precursor to Homo sapiens colonized
much of central and western Europe with the aid of a mature Acheulian technology.
The earliest of those fossils and assemblages date to 600,000 years ago.
Paleoanthropologists have argued for years about the name of this hominid
species. Recently, Philip Rightmire of Binghamton University has proposed
that a number of similar cranial and dental fossils from across Africa and
Europe can be assigned to the species Homo heidelbergensis, which
was first applied to a jaw found at Mauer, near Heidelberg, Germany, in
1908. Homo heidelbergensis is best described as a large-brained form
of Homo, but still with a massive face. This hominid seems to have
emerged in southern Africa around an advanced Acheulian technology at sites
such as Bodo and Elandsfontein. The combination of a large brain and an
advanced technology may account for the hominid's quick dispersion into
Europe, as both Homo heidelbergensis and the Acheulian appear at
sites such as Mauer and Boxgrove (in far northern Europe) by 500,000 years
ago. In Europe, Homo heidelbergensis is the hominid that begins to
show traits similar to the Neanderthals about 250,000 years ago, starting
a trend of anatomical specialization that probably leads to extinction less
than 30,000 years ago. Neither Homo heidelbergensis nor the Acheulian
follow the path of early dispersal across southern Asia.
In Europe, as in Asia, recent finds and more penetrating age analyses bring
up the possibility of African arrivals earlier than commonly hypothesized.
Thus at Isernia la Pineta, in southern Italy, an elementary core-flake assemblage
has a date of about 800,000 years ago, based on paleomagnetic and biostratigraphic
methods. Even more intriguing are two Spanish sites where recent excavations
have produced hominids and technological assemblages at an equally early
age. At Atapuerca, in north-central Spain, core and flake tools accompany
an early representative of Homo at greater than 780,000 years ago.
Artifacts in a yet lower level of this locality may be significantly older.
At Orce, in south-central Spain, excavators have recovered simple core and
flake tools as well as purported hominid skull fragments and limb elements.
Paleomagnetic analysis suggests an age of about 1.0 mya. Although hominid
taxonomy and age determinations are tenuous at both localities, the Spanish
sites represent possible evidence for an early species of Homo arriving
from Africa before Homo heidelbergensis and its Acheulian technology.
It is also possible that Homo reached Europe via Gibraltar at least
once.
© American Scientist 1996
