An international team of geneticists and AI experts, led by Joshua Akey from Princeton University, has uncovered new insights into the genetic relationship between modern humans and Neanderthals.

The study utilized genomic data from 2,000 living humans, three Neanderthals, and one Denisovan, employing a machine learning tool called IBDmix to trace genetic flow over the past 250,000 years.

Researchers identified three significant waves of contact between modern humans and Neanderthals: the first occurred 200,000 to 250,000 years ago, the second from 100,000 to 120,000 years ago, and the largest wave from 50,000 to 60,000 years ago.

These interactions suggest that modern humans migrated out of Africa and back more frequently than previously thought, coexisting with Neanderthals for approximately 200,000 years before their extinction around 30,000 years ago.

The research indicates that there were multiple waves of interbreeding between modern humans and Neanderthals, challenging previous beliefs about their interactions.

The findings support the 'assimilation model' proposed by Fred Smith in 1989, suggesting that Neanderthals were absorbed into modern human populations rather than facing outright extinction.

By searching for modern human DNA in Neanderthals, the team discovered that many Neanderthal offspring likely remained within their populations, leaving little trace in modern humans.

Additionally, the estimated Neanderthal breeding population size was revised down from about 3,400 to 2,400 individuals, indicating a smaller population than previously believed.

These findings enhance our understanding of human evolution, emphasizing a complex history of migration and interaction between early humans and Neanderthals.

The research also revealed that Neanderthals were skilled hunters and toolmakers, challenging earlier stereotypes of them being unintelligent and primitive.