Origin: A Genetic History of the Americas

haplogroups found in the First Peoples of the Americas was estimated at
either between 20,000 to 15,000 years ago or between 30,000 to 20,000
years ago (see the “Mitochondrial and Y Lineages in the Americas” sidebar
in chapter 1 for a more recent and precise estimate). Neither of these was
compatible with the Clovis First model of initial peopling around 13,000-
ish years ago.
As geneticists were working on calculating these dates—and arguing
whether the Americas were peopled in a single migration or several—
archaeologists were turning up more and more convincing evidence of
humans’ presence in the Americas before Clovis.
THE RISE AND FALL OF THE THREE-WAVE MIGRATION
HYPOTHESIS
Evidence about the past from different fields can be frustratingly
hard to integrate and interpret. In 1986, when anthropological
genetics was still a very young field, a group of three
researchers—Joseph Greenberg (linguist), Christy Turner II
(anthropological linguist), and Stephen Zegura (anthropological
geneticist) attempted to reconcile the then available linguistic,
genetic, and dental evidence to produce a unified model for the
peopling of the Americas. Their model rested on the assumption
that the Americas were peopled by anatomically modern
humans from Asia after the terminal Pleistocene.
The savvy reader will notice that we have not talked about
linguistics much in this book. That is certainly not because I
believe that linguistic evidence can’t tell us much about human
history—quite the contrary! The extraordinary diversity of
language families in the Americas suggests that humans have
been present in the Western Hemisphere for a very long period
of time.
It is generally accepted by many linguists that there is a