The Genomic Timeline of Becoming Homo sapiens

Rewriting the Genetic History of Modern and Archaic Humans

Modern humans carry a genetic record that connects us to ancient populations like Neanderthals and Denisovans. A new study, led by Luca Pagani and colleagues and published on the preprint server bioRxiv¹, dives deeply into the genetic transitions that sculpted Homo sapiens. The research challenges long-standing assumptions about when and how key genomic features emerged, suggesting that many hallmarks of modern humans originated before our lineage split from archaic relatives.

Parsing the Timeline of Evolutionary Events

The researchers analyzed genomic sequences from modern humans, Neanderthals, and Denisovans, identifying key moments that shaped our evolutionary trajectory. Using tools like coalescence analyses and molecular clock assessments, they reconstructed a timeline of genetic shifts divided into three major events:

Events Partitioning. Defining Event 1 (the period preceding the separation between modern and archaic lineages, characterized by a putative bottleneck at around 1000 kya), Event 2 (the separation of modern and archaic lineages, at around 650 kya) and Event 3 (the contribution of modern human lineages to the gene pool of Neanderthals, after 350 kya), along the population tree of modern and archaic humans. The gene tree depicted in red exemplifies a Human650 region that entered and was also fixed within the Neanderthal gene pool as a consequence of Event 3.