Neanderthal–Sapiens Interbreeding Study Reveals Directional Mating Bias and Two Unknown Archaic Lineages

Genetic analysis of Neanderthal and modern human DNA shows that most interbreeding events involved Neanderthal males and Homo sapiens females, a pattern inferred from the distribution of Neanderthal DNA on the X chromosome. The study, led by researchers at the University of Pennsylvania, argues that this directional bias persisted for thousands of years.

A separate investigation by scientists at the University of California, Berkeley introduced a new computational method called TRACE, which identified DNA from two previously unknown archaic hominin groups: one that interbred with modern humans in Africa more than 50,000 years ago, and another that contributed DNA in Eurasia over 1.7 million years ago. These “ghost” lineages account for about 1% of the genome of all present‑day humans and have influenced traits such as skin pigmentation and immune function.