May 16, 2003
24,000-year-old European mtDNA
An interesting study of 24,000-year-old mtDNA from Southern Italy sheds some light on the earliest Europeans.
Evidence for a genetic discontinuity between Neandertals and 24,000-year-old anatomically modern Europeans.
Caramelli D et al.
Proc Natl Acad Sci U S A 2003 May 12; [epub ahead of print]
Abstract
During the late Pleistocene, early anatomically modern humans
coexisted in Europe with the anatomically archaic Neandertals for
some thousand years. Under the recent variants of the multiregional
model of human evolution, modern and archaic forms were
different but related populations within a single evolving species,
and both have contributed to the gene pool of current humans.
Conversely, the Out-of-Africa model considers the transition between
Neandertals and anatomically modern humans as the result
of a demographic replacement, and hence it predicts a genetic
discontinuity between them. Following the most stringent current
standards for validation of ancient DNA sequences, we typed the
mtDNA hypervariable region I of two anatomically modern Homo
sapiens sapiens individuals of the Cro-Magnon type dated at about
23 and 25 thousand years ago. Here we show that the mtDNAs of
these individuals fall well within the range of variation of today’s
humans, but differ sharply from the available sequences of the
chronologically closer Neandertals. This discontinuity is difficult to
reconcile with the hypothesis that both Neandertals and early
anatomically modern humans contributed to the current European
gene pool.
...
Specific mtDNA sites outside HVRI were also analyzed (by
amplification, cloning, and sequencing of the surrounding region)
to classify more precisely the ancient sequences within the
phylogenetic network of present-time mtDNAs (35-36).
Paglicci-25 has the following motifs: 17,025 AluI, 00073A,
11719G, and 12308A. Therefore, this sequence belongs to either
haplogroups HV or pre-HV, two haplogroups rare in general but
with a comparatively high frequencies among today’s Near-
Easterners (35). Paglicci-12 shows the motifs 00073G, 10873C,
10238T, and AACC between nucleotide positions 10397 and
10400, which allows the classification of this sequence into the
macrohaplogroup N , containing haplogroups W, X, I, N1a, N1b,
N1c, and N*. Following the definition given in ref. 36, the
presence of a single mutation in 16,223 within HRVI suggests a
classification of Paglicci-12 into the haplogroup N*, which is
observed today in several samples from the Near East and, at
lower frequencies, in the Caucasus (35). It is difficult to say
whether the apparent evolutionary relationship between
Paglicci-25 and Paglicci-12 and those populations is more than
a coincidence. Indeed, the haplogroups to which the Cro-
Magnon type sequences appear to belong are rare among
modern samples, and therefore their frequencies are poorly
estimated. However, genetic affinities between the first anatomically
modern Europeans and current populations of the Near
East make sense in the light of the likely routes of Upper
Paleolithic human expansions in Europe, as documented in the
archaeological record (37).