GENETICS × PEOPLING
Ust'-Ishim, Oldest Modern Human Genome
~45,000 years ago
Palaeolithic · Upper Palaeolithic · Last glacial
The oldest modern human genome sequenced so far comes from one thigh bone found in western Siberia, called Ust'-Ishim after the place where it came to light. Its owner died about 45,000 years ago, and enough of his DNA had survived for a high-quality sequence to be published in 2014. He belonged to a population living before the split between western and eastern Eurasians, or at the same moment as it, and carries about as much Neanderthal ancestry as Eurasians do today. The shape of that ancestry matters more than its quantity: inherited blocks are cut a little shorter at every generation, when chromosomes are reshuffled before a cell becomes a gamete, so a long block means a recent ancestor. His Neanderthal segments are substantially longer than any found in living genomes, which places the interbreeding 7,000 to 13,000 years before his own lifetime.
Why it matters
Dating the meeting with Neanderthals had until then depended on the genomes of living people, in which the signal has been ground down by 45,000 further years of reshuffling. A genome that is itself old stands nearer the event: the interbreeding falls between about 60,000 and 50,000 years ago, close to the dispersal out of Africa rather than long after it. Comparison with later genomes detects no contribution from this man to the populations that follow, which makes him a witness of the expansion and not an ancestor.
Dating & uncertainty
Radiocarbon dates the bone to about 45,000 years, and the genetic clock agrees with it: applied to five Upper Palaeolithic genomes, the recombination method tracks their radiocarbon ages closely, and yields in passing a mean generation interval of 26 to 30 years. What has since been contested is the superlative. A skull from Zlatý kůň in Czechia, sequenced in 2021, carries Neanderthal segments longer than those of Ust'-Ishim, which places that woman nearer the admixture and therefore, in all likelihood, earlier. Should that reading hold, Ust'-Ishim gives up the title of oldest sequenced modern human while keeping its role as the reference point, being the one that a radiocarbon date pins down.
Sources
- Fu et al. (2014), Nature · Genome sequence of a 45,000-year-old modern human from western Siberiadoi:10.1038/nature13810
- Moorjani et al. (2016), Proceedings of the National Academy of Sciences · A genetic method for dating ancient genomes provides a direct estimate of human generation interval in the last 45,000 yearsdoi:10.1073/pnas.1514696113
- Prüfer et al. (2021), Nature Ecology & Evolution · A genome sequence from a modern human skull over 45,000 years old from Zlatý kůň in Czechiadoi:10.1038/s41559-021-01443-x
- Hajdinjak et al. (2021), Nature · Initial Upper Palaeolithic humans in Europe had recent Neanderthal ancestrydoi:10.1038/s41586-021-03335-3
Our species’ history as one day
20:34:173 h 26 min before midnight
if the 315,000 years of Homo sapiens were compressed into a single day