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are associated in modern populations
with type A-positive blood and brown
eyes, as well as with thick, dark hair and
large, flat front teeth typical of Asians
and Native Americans. Inuk also possessed DNA signatures for an increased
susceptibility to baldness, dry earwax
characteristic of Asian populations,
a relatively slow metabolism and the
broad, short body type commonly found
in residents of cold climates.
DNA analyses of ancient humans and
their ancestors usually face enormous
technical challenges. Fossil bones get
contaminated with the DNA of those
who unearth these finds as well as with
fungal and bacterial DNA. Measures
to enrich paltry ancient DNA samples
include generating multiple samples of
the same genetic sequences and isolating genetic fragments that show no signs
of contamination.
Because DNA from hair typically contains little contamination from fungi or
bacteria, Rasmussen’s team focused on
Inuk’s locks. Frozen conditions following
death also helped to preserve Inuk’s DNA
and reduce contamination. The team
generated 20 copies of his genome to
Genetic material extracted from hair of
a long-dead Greenland man suggests
that he had brown eyes and dark hair,
as depicted in this artist’s illustration.
confirm that significant contamination
had not occurred.
About 84 percent of the DNA extracted
from Inuk’s hair was his. Rasmussen’s
team then sequenced 79 percent of
Inuk’s nuclear DNA and identified more
than 353,000 base pair variations.
“It is amazing how well-preserved
this ancient genetic sample is, presum-
ably due to its rather young age and
the permafrost in which it was found,”
remarks geneticist Svante Pääbo of the
Max Planck Institute for Evolutionary
Anthropology in Leipzig, Germany.
Back Story | NE W WORLD MIGRATIONS
DNA analyses have hinted at a number of possible dates and patterns for the peopling of the Americas.
3 Analyses of two rare sequences of mitochondrial DNA suggest that two separate groups
trekked across the land bridge and went their
separate ways. Other groups may have also
made separate entries (SN: 1/31/09, p. 5).
1 Early mitochondrial DNA analyses suggested three waves of migration that correspond to three Native American language
groups — Amerind (brown arrow), Na-Dene
(blue arrow) and Eskaleut (orange arrow).
2 Another study suggests that a founding group
of up to 5,400 people settled in Beringia (blue
arrow) and later moved south and east, once the
snow blocking their entry into the heart of the
Americas melted (SN: 2/16/08, p. 102).
