Biology Reference
In-Depth Information
been processed in a heavy-duty detergent and soaked in bleach after it had been found, all of
which would have significantly deteriorated any possible remaining DNA.
Later, one of the original investigators of the Leoma Patterson case rediscovered a hair mat
that had been at the site where the skeleton had been found. That hair mat was sent to Dr. Esh-
leman, who then took two samples that he and another specialist independently worked on in
different laboratories. This time the sample did yield mtDNA. At this point neither specialist
had prior knowledge of what the DNA of the maternal relatives looked like, but when they
finally made a comparison, the DNA from the hair mat matched those of the surviving
maternal relatives. Case solved: the exhumed skeleton was that of Leoma Patterson.
Here you can see that had the sample been sent to an experienced researcher and labora-
tory from the start, many of the problems would have been avoided, including the mis-
leading information received from the first analysis. The original lab was clearly not used
to dealing with skeletal samples and did not grasp the level of ambiguity that potential
contamination can introduce.
APPLICATION OF DNA ANALYSIS TO LONG-STANDING
ANTHROPOLOGICAL INQUIRIES INTO HUMAN VARIATION,
ITS PATTERN, AND ITS EXPLANATION
Without a doubt, genetic studies, whether conducted independently or in concert with
morphological studies will influence future anthropological inquiry. Already we have seen
their impact on important issues, the single most persistent of which is the biological race
concept as it applies to humans. Though anthropologists have rejected the categorical
view of biological race, bioanthropologists continue to apply it as a useful heuristic to
describe patterns of human biological variation. As we bring more data and analysis to
bear on the description and understanding of patterns of human variation, the ways in which
the biological race concept is used within bioanthropology are likely to change in response.
Human Genetic Variation: Is it Patterned?
Recent genomic studies argue that it is. A relatively recent set of landmark papers by
Rosenberg and colleagues (
Rosenberg et al., 2002, 2005
) looked at almost 400 STRs in a little
over 1000 individuals from 52 globally distributed populations. They argued that despite the
fact that over 90% of the STR variation could be found within populations, there was still
3
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5% of STR variation that differentiates on a “major” or continental level. This finding is
apparently robust (
Rosenberg et al., 2005
). This means that some human genetic variation
can form clusters that correspond with major geographic areas, which in turn broadly corre-
spond to traditionally used racial categories.
What Are the Possible Evolutionary Explanations for the Pattern?
In the last few years there has been intense discussion in the scholarly literature of what
evolutionary process(es) produced this continental distribution of human variation. At first,
several contemporaneous studies demonstrated that human genetic variation conforms to
