Archaeology Magazine - November/December 1996 - 128

North, Central, and South America," he says. "It is not
realistic to believe that the same lineages ended up in all
these populations across two continents by separate
migrations."
Merriwether believes the first Americans came from a
single population in Asia, probably in a single wave,
though the wave may well have lasted for some thousands of years. "From the data I look at there is no way
to tell how long the door was open, but you can easily
imagine it as anywhere from one big migration with lots
of people to a sort of continuous migration over a long
period of time." What the genetic evidence does not tell
us, according to Merriwether, is when they arrived.
Unlike Torroni and Schurr, he contends that some of the
variation within the A, C, and D lineages occurred
before the arrival of Native Americans in the New
World. If so, the dates calculated for their arrival would
be inflated. This, Merriwether says, may also explain

why the B lineage appeared to be younger than the
other three in Torroni and Schurr's analysis. He argues
it arrived at the same time as the others but with less
variation. Merriwether also does not agree that Native
Américain and Siberian populations are descended from
a common ancestor. He believes that the absence of the
B lineage in indigenous Siberians rules out such a possibility. A better match, he says, can be found in Tibetans,
who have eight of the nine mtDNA lineages known in
Native Americans, and in Mongolians; who have seven.
Because the Tibetans studied were identified by Torroni
as displaced Mongolians, Merriwether concludes that
Mongolians and Native Americans are descended from a
single ancestral population. An independent study of
mtDNA variation in Mongolian populations by Connie
Kolman of the Smithsonian Tropical Research Institute
reached the same conclusion. The date of this divergence
has yet to be established.

a new study, Texas A&M University chemists Ronnie Reese, Marian
Iii Hyman, and Marvin Rowe and biologists James Derr and Scott Davis applied
DNA analysis to the paints used on rock
art in the Lower Pecos region, at the confluences of the Pecos, Devils, and Rio
Grande rivers in southwestern Texas.
Rock art weis an essential component of
many ancient symbolic, religious, and
artistic systems, and the materials used for
preparing paints may have had special
significance. In the Lower Pecos area a
variety of minerals were used in pictographs. Dark and light red, black, yellow, and orange pigments are common,
prepared from iron and manganese oxides
I
and hydroxides. White is rare. Until now,
*
was
known
however, virtually nothing
about the organic substances that served
I
as binders for the pigments. Many readily
i
oo
available materials may have been usedDNAanalysis, left, of two rock-art pigment samplesfrom a Pecos River,
blood, urine, milk, eggs, vegetable juices,
or animal fats- but no chemical or bioTexas,pictograph, like the one at right,
sequence of bases (A, C, G,
and
in
amino
acids
similar
to
that
or
bison.
deer
had
been
The
T)
of
logical analyses
attempted.
Texas A&M researchers used samples
from two Pecos River-style pictographs in Seminole
related to that of deer and bison. The binder may have
that
had
been
dated
to
ca.
to
been
bone marrow, which would be a good source for
2,950
Canyon
directly
was
chosen
the
The
site
because
4,200 years ago.
DNA; blood is questionable since mammalian red
picthere
have
severe
exfoliation
blood
cells lack nuclei (only scarcer white blood cells
undergone
tographs
more than 50 percent have spalled from the limestone
have them). Now that the general identity of the
wall. The pigment layer, sandwiched between the limeorganic component has been established, part of the
stone and later calcite and gypsum deposits, was intact.
sequence that is more susceptible to diagnosis will be
examined to determine which animal was used. - M.R.
Nuclear DNA recovered from it proved to be closely

November/December 1996

Archaeology Magazine - November/December 1996

Table of Contents for the Digital Edition of Archaeology Magazine - November/December 1996