Oldest non-human DNA

Using the latest techniques in ancient DNA extraction and sequencing, scientists recovered genomic DNA from the molar teeth of Early Pleistocene mammoths, resembling those of steppe mammoths (Mammuthus trogontherii), dating back at least 1.1 million years, and perhaps as long ago as 1.65 million years. This is the first time that DNA exceeding 1 million years old has been retrieved from any ancient organism. The oldest tooth sampled for DNA was excavated from the permafrost near the village of Krestovka in north-eastern Siberia, by the late Russian palaeontologist Andrei Sher in the 1970s. The findings were published in the journal Nature on 17 February 2021.

The upper age bound (1.65 million years) is based on genetic dating, while the lower age bound (1.1 million years) is based on the sediment where the teeth were found.

Another steppe mammoth tooth collected near the village of Adycha in Siberia wielded similarly ancient DNA, with an estimated age span of 1–1.3 million years.

Siberian steppe mammoths were the common ancestors to both the gigantic North American Columbian mammoths (M. columbi) that appeared some 1.5 million years ago, as well as the iconic woolly mammoths (M. primigenius) that emerged c. 700,000 years ago, before becoming widespread across the northern parts of Eurasia and North America. Crucially, this study demonstrated genetic differentiation that was already taking place among Siberian steppe mammoth populations, with the Krestovka mammoth having closer affinities to North American Columbian mammoths, but the Adycha mammoth being closer to later woolly mammoths. The new study also identified an interbreeding event c. 500,000 years ago between woolly mammoths and an early population of North American Columbian mammoths. The legacy of which is that subsequent Columbian mammoth populations carry mitochondrial DNA genome of woolly mammoth ancestry.

The previous oldest DNA had been sequenced from the leg bone of a horse found in the Yukon Territory, Canada, that was dated to between 560,000 and 780,000 years old in 2013. The oldest DNA from a non-permafrost site was extracted from a fragment of cave bear skull excavated from Kudaro Cave in the Caucasus Mountains, dating back 360,000 years, published in another 2021 study