Origin: A Genetic History of the Americas

The paper was immediately excoriated by other linguists.
The root of Greenberg’s hypothesis, and the reason why it was
controversial, was not because he “discovered” a later migration
of Arctic peoples using linguistic data; that was already well
understood from Arctic peoples’ own oral histories,
archaeological data, biological data, and linguistic data
preceding Greenberg’s work. Rather, Greenberg’s hypothesis
was controversial because he grouped all other languages
(besides those spoken by Athabaskans and Arctic peoples) into
the Amerind category. In a famous critique, Johanna Nicols
countered that the diversity among the languages grouped as
“Amerind” would require something on the order of 35,000 years
to develop, not the 12,000 years Greenberg assumed to fit the
Clovis First hypothesis.
The methods which he used to construct these groupings
were considered highly problematic by his colleagues.
Greenberg did not distinguish between homology and other
factors that might cause words to resemble each other. This
resulted, critics argued, in fundamental errors that were fatal to
his classification scheme. Furthermore, the alleged
“correspondences” between linguistic, genetic, and
morphological groupings broke down when it came to specifics:
The so-called Greater Northwest Coast Group identified by
dental traits did not correspond to the Na-Dene linguistic
grouping—it included Inuit-Aleut speakers and other people who
would have been classified as Amerind by Greenberg. The
genetics data did not fit either.
Despite these flaws, some geneticists eagerly adopted the
model. The three-wave migration hypothesis became the
standard model that all genetics studies of peoples in the
Americas tested with new evidence for decades. Between 1987
and 2004, 80 out of the 100 papers published on genetic
variation in Native American populations were influenced by (or
mentioned) this model.
Eventually, however, mitochondrial and Y chromosome DNA
produced clear patterns that did not correspond to these