The Human Family Tree is a Bush

More evidence of branching off and reconnecting in the early history of humans

It has been an exciting week week for human ancestry. First, a new species of hominid was identified in the Philippines, Homo luzonensis, and now there’s evidence of the formerly elusive Denisovans in the ancient ancestry of Papuans. Adding to the excitement, this group found evidence of at least three distinct Denisovan lineages, and that humans likely interbred with Denisovan cousins somewhere around New Guinea. This is all pretty amazing, considering we first became aware of Denisovans from a single DNA sample from a finger, found in a cave, in Siberia.

Multiple Deeply Divergent Denisovan Ancestries in Papuans

Jacobs et.al, Cell (Research Article)

Highlights

•A new dataset of 161 genomes covering the understudied Indonesia-New Guinea region

•Introgressing Denisovans comprise at least three genetically divergent groups

•Papuans carry haplotypes from two Denisovan groups, with one unique to Oceania

•Some Denisovan introgression was recent and likely occurred in New Guinea or Wallacea

Summary—Genome sequences are known for two archaic hominins—Neanderthals and Denisovans—which interbred with anatomically modern humans as they dispersed out of Africa. We identified high-confidence archaic haplotypes in 161 new genomes spanning 14 island groups in Island Southeast Asia and New Guinea and found large stretches of DNA that are inconsistent with a single introgressing Denisovan origin. Instead, modern Papuans carry hundreds of gene variants from two deeply divergent Denisovan lineages that separated over 350 thousand years ago. Spatial and temporal structure among these lineages suggest that introgression from one of these Denisovan groups predominantly took place east of the Wallace line and continued until near the end of the Pleistocene. A third Denisovan lineage occurs in modern East Asians. This regional mosaic suggests considerable complexity in archaic contact, with modern humans interbreeding with multiple Denisovan groups that were geographically isolated from each other over deep evolutionary time.

Read the original article HERE … and other summaries here and here.