Ancient DNA reveals two unknown human lineages hidden in modern genomes

​Representative Image of ancient human evolution showing the genetic connections between humans, Neanderthals, and Denisovans (AI-generated image) Modern humans already carry small amounts of Neanderthal and Denisovan DNA, evidence that our ancestors interbred with other human groups tens of thousands of years ago. Both lineages are known from ancient remains, including fossils from which scientists have successfully recovered DNA. Now, researchers at the University of California, Berkeley have identified genetic signatures from 2 additional ancient human lineages whose DNA has never been recovered directly from a fossil. One appears to have split from the lineage leading to modern humans around 800,000 years ago before eventually interbreeding with an ancestral human population in Africa. The other is far older, splitting from the human lineage roughly 1.8 million years ago before its descendants passed genetic material into Denisovans, who later transmitted a small portion of it to modern humans. The findings suggest that ancient human evolution involved repeated encounters and exchanges between populations that have left almost no physical trace behind.How TRACE found ancient DN...