Study finds modern humans carry DNA from two previously unknown extinct human lineages via new TRACE method
Every person alive today carries DNA from two extinct human relatives science did not know existed. A new method called TRACE found a ghost lineage that interbred with humans in Africa over 50,000 years ago, and a super-archaic lineage from 1.8 million years ago tied to Denisovan
Every person alive today carries genetic material from two extinct human lineages that scientists did not know existed until this study. Researchers developed a new computational method called TRACE, short for TRacking Archaic Contributions via ARG Estimation, to reconstruct genealogical relationships hidden inside hundreds of modern human genomes and identify DNA segments whose ancestry stretches back further than previously detected. The team identified a ghost lineage that interbred with modern humans in Africa more than 50,000 years ago, contributing about 0.5 to 1 percent of the genome in people today, and which itself split from the ancestors of modern humans roughly 800,000 years ago, around the same time Neanderthals and Denisovans branched off. A second population, described as super-archaic, diverged even earlier, about 1.8 million years ago, and interbred with Denisovans in Eurasia before that DNA reached modern humans secondhand through later interbreeding with Denisovans. The findings, published in the journal Science, add two more branches to a human family tree that already included Neanderthals and Denisovans.