A newly published paper by an international group of collaborators demonstrates that ancient horse populations in North America and Eurasia maintained contact for hundreds of thousands of years, rather than becoming separate species. It is from this stock that the modern domestic horse developed.
The study, led by Alisa Vershinina, PhD, from the Paleogenomics Lab at University of California Santa Cruz, investigated whether certain kinds of genetic signals were shared by ancient horse populations on either side of the Bering Strait. These signals were embedded in their genomic sequences, which can be retrieved using DNA techniques. Using a forensic approach, the study’s authors show that ancient horse migrations can be traced over great distances. Modern horses first migrated from North America to Eurasia across a then-existing land bridge, called Beringia, about 1 million years ago. The bridge finally disappeared around 14,000 years ago. Until now, it was uncertain whether horse populations were able to maintain biological contact when the land bridge was intact.
“Genetics is destiny. Think of paleogenetics as seeing destiny in a rearview mirror,” said co-author Ross MacPhee, PhD, a senior curator at the American Museum of Natural History and head of the science committee at the CANA Foundation. “This study establishes that the connection between horse populations persisted until Beringia could no longer be crossed. They were the same species because they never lost the ability to interbreed.”
“This same pattern of genetic interchange across Beringia characterizes other ice age mammal species, such as bison, so the horse story is not unique,” said Grant Zazula, PhD, director of the Yukon Paleontology Program and another co-author.
The study will appear in an upcoming issue of the science journal, Molecular Ecology. The CANA Foundation has partly supported the Paleogenomics Lab at UCSC.