A new genomic analysis of ancient cattle appearing in this week's Science reveals complex regional variation that has been obscured by admixture in modern-day populations. In the study, a group led by investigators at Trinity College compare the genomes of 67 early domestic cattle known as Bos taurus to the genome of their progenitor, the extinct Eurasian auroch Bos primigenius. They find that the first domesticated cattle populations had diverse origins among aurochs with multiple separate introgressions of wild stock, and that several thousand years later during a multi-century drought there was a rapid and widespread introgression of zebu, Bos indicus, from the Indus Valley. This introgression of drought-tolerant zebu may have helped domestic cattle survive in arid conditions, they write.
Archeological findings, bolstered by genomic analyses, suggest that humans began populating the American continents around 15,000 years ago — earlier than had previously been believed, according to a review appearing in Science this week. Over the past 30 years, archaeological investigations in North and South America revealed human occupations predating what had previously been believed to be the oldest sites of human settlement in the Americas, Texas A&M University's Michael Waters writes. "In tandem with these archaeological discoveries, genetic studies of contemporary Indigenous Americans and prehistoric individuals provided new perspectives on the origin and population history of the first Americans." Now, through a combination of genomics and archeology, researchers find that regional complexes were established by humans at least 13,000 years ago in North America, about 12,900 years ago in South America, and that a western coastal route for migration might have been available as early as 16,000 years ago.