Goldfish Learn To Drive

Pediatrician Erica Esrick
is testing a possible gene 
therapy for sickle cell disease. The painful, life-threatening 
disorder affects millions of people around the world.
Philosopher of science Yafeng Shan 
looks back at how the 
study of Mendelian genetics as we know it today emerged 
from a muddle of ideas at the turn of the 20th century.
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www.sciencenews.org 
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February 12, 2022 
29
CENTER FOR THE STUD
Y OF THE FIRST AMERICANS/TEXAS A&M UNIV
.
Scientific understanding of the peopling 
of the Americas is as unsettled as the 
Western Hemisphere once was. Skeletal 
remains, cultural artifacts such as stone 
tools and, increasingly, microscopic 
pieces of ancient DNA have sparked 
heated debates about which of several 
origin stories best explains available 
evidence. Additional conflict stems from a tragic scientific 
legacy of ignoring and exploiting Indigenous groups whose 
ancestries are on the line.
Anthropologist and geneticist Jennifer Raff offers her take 
on the state of this fascinating and turbulent research field 
in Origin: A Genetic History of the Americas.
Raff wants to tell the most accurate, if still incomplete, 
story of how humans settled the Americas by integrating 
research on ancient and modern DNA with archaeological 
finds. She refers to people who inhabited the Western 
Hemisphere before Europeans arrived as First Peoples, 
a term favored by some of her Indigenous colleagues.
Most researchers think that ancestors of the First Peoples 
lived in Siberia and East Asia 20,000 years ago or more dur-
ing the Ice Age, Raff explains. A consensus view holds that 
those groups eventually crossed a now-submerged expanse 
of land — the Bering Land Bridge — that connected north-
eastern Asia and North America. Analyses of ancient human 
DNA indicate that these migrants gave rise to populations 
that lived south of an ice sheet that ran across northern 
North America from around 80,000 to 11,000 years ago. But 
much remains unexplained.
Raff delves into several competing models of how, when 
and where people first made inroads into the Americas. One 
approach holds that Ice Age Siberians, known from archaeo-
logical finds, reached North America between 16,000 and 
14,000 years ago and, within a few millennia, journeyed 
south across the continent through a gap in the melting ice 
sheet. Those settlers probably founded the Clovis culture, 
known for its distinctive stone points (SN: 1/15/22, p. 22).
Another view contends that people came to the Americas 
much earlier, 30,000 years ago or more. A minority of 
researchers in this camp contends that settlers may 
have even reached what’s now southern California by 
130,000 years ago (SN: 5/27/17, p. 7).
But archaeological and genetic evidence best fits a third 
model, Raff writes. In this scenario, First Peoples reached the 
Americas as early as 18,000 years ago and perhaps over 20,000 
years ago. These folks — including groups that were not prede-
cessors of Clovis people — probably traveled by boat or canoe 
along North America’s west coast, arriving in South America 
no later than about 14,000 years ago (SN: 12/26/15, p. 10).