Red hair isn’t all we got from Neanderthals. Without DNA gleaned from extinct human species our ancestors might never have survived Earth’s extremes

Modern Tibetans have Denisovan genes that may help them cope with altitude Reuters

Dozens of genes found in humans today have been traced to Neanderthals and Denisovans. They made their way into the human species when some of our direct ancestors mated with ancient lineages that are now extinct.

Interbreeding like this happened in Africa and in Eurasia, producing many human hybrids – you can read more about them here. Recent genetic decoding has revealed that it partly accounts for differences in our physical appearance – things like skin and hair colour – and affects our health.

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Some of this “undead” DNA even helped us survive in places we were otherwise ill-equipped for. Here are four examples.

1. High-altitude survival

Perhaps the most dramatic evidence of modern benefits from ancient DNA is seen in Tibetans. Emilia Huerta-Sánchez at the University of California in Merced and her colleagues found that about 80 per cent of Tibetans carry a particular piece of Denisovan DNA. Most bits of Denisovan DNA are not present in more than 0.2 per cent of East Asians, so geneticists suspected the ancient DNA must have given its Tibetan owners significant advantages.

The stretch of ancient DNA overlaps with the EPAS1 gene, the Denisovan version of which seems to help people survive the low-oxygen conditions at high elevations. It’s possible that Denisovans were adapted to life at altitude and passed the trait to …