GENETICS

The Denisovan Inheritance

~46,000 years ago

Palaeolithic · Upper Palaeolithic · Last glacial

As modern humans spread across Asia, they met and mixed with Denisovans not once but repeatedly: genomes from Island Southeast Asia and New Guinea carry DNA from two deeply divergent Denisovan lineages, separated for over 350,000 years, and East Asians carry a third. In Papuans, the archaic share reaches several percent of the genome, and some of it kept arriving until near the end of the ice age.

Why it matters

The inheritance is not inert. In Tibetans, a version of the gene EPAS1, acquired from Denisovan relatives, tunes the blood's response to thin air and makes life at high altitude possible; it is the textbook case of borrowed adaptation. A people known from a few teeth, a finger bone and a jaw survives mostly as passages inside us, doing work to this day.

Dating & uncertainty

These encounters are not dated like fossils: their traces are the lengths of archaic DNA segments in living genomes. The models point to several pulses involving at least three distinct Denisovan populations; the anchor follows the main pulse into the ancestors of Papuans, and gene flow east of the Wallace Line seems to have continued until near the end of the Pleistocene.

Sources

1. Jacobs et al. (2019), Cell · Multiple deeply divergent Denisovan ancestries in Papuansdoi:10.1016/j.cell.2019.02.035
2. Browning et al. (2018), Cell · Analysis of human sequence data reveals two pulses of archaic Denisovan admixturedoi:10.1016/j.cell.2018.02.031
3. Huerta-Sánchez et al. (2014), Nature · Altitude adaptation in Tibet caused by introgression of Denisovan-like DNAdoi:10.1038/nature13408

Our species’ history as one day

20:29:423 h 30 min before midnight

if the 315,000 years of Homo sapiens were compressed into a single day