杏吧原创

Common colds and cold sores have afflicted us for at least 31,000 years, according to a study that found DNA from viruses in ancient teeth.

What鈥檚 more, the sniffles may have plagued us for far longer. The DNA of one virus suggests it first evolved around 700,000 years ago 鈥� suggesting viruses that cause colds predate our species, and also troubled our Neanderthal cousins.

The preserved virus is 鈥渢he oldest virus in humans yet鈥�, says , who carried out the work at the University of Copenhagen in Denmark.

She and her colleagues studied two fragmented milk teeth that were excavated at Yana in north-east Siberia. The teeth are 31,600 years old, making them the oldest human remains found so far north. Two years ago, researchers led by , also at the University of Copenhagen, obtained human DNA from the teeth.

Holtsmark Nielsen has now revisited the DNA from the teeth to look for genes from infectious organisms. She found low-quality DNA from four species of herpesvirus. These included herpes simplex, the virus that causes cold sores.

Her team also recovered two high-quality genomes of human adenovirus C, which today is a common infection. 鈥淵ou almost certainly have had it as a kid, pretty much everyone has been infected with it,鈥� says Holtsmark Nielsen. 鈥淚t鈥檚 usually a bit like a cold.鈥�

Previously, the oldest direct evidence of an identifiable virus infecting a human was from just 7000 years ago: researchers found that . It has also been possible to identify bacterial infections from within the past 10,000 years, after the advent of farming, but not from earlier periods.

鈥淚t鈥檚 really a remarkable technical accomplishment to be able to extract this kind of information from material that is that old,鈥� says at the University of Wisconsin-Madison. However, she says it isn鈥檛 clear that the ancient viruses only caused mild illnesses, as even today adenovirus and herpesvirus do sometimes cause serious illness.

The researchers also estimated when adenovirus C first began infecting humans. To do so, they compared the ancient viral DNA with that of modern strains of the virus, and estimated how long ago their shared ancestor lived. It turned out that the shared ancestor of all the adenovirus C samples lived between 487,000 and 963,000 years ago, with a best estimate of 702,000 years ago.

That is long before the origin of our species Homo sapiens, the oldest known remains of which are between 250,000 and 350,000 years old. Before our species arose, other hominins like Homo erectus lived in Africa and Eurasia. Between 400,000 and 800,000 years ago, an unidentified ancestral group gave rise to three largely distinct populations: our species, the Neanderthals who lived in Europe and western Asia听补苍诲 the Denisovans who lived in eastern Asia.

鈥淭his particular adenovirus C鈥� has probably been around as long as humans in the broad sense were around, including Neanderthals, including sapiens, including probably erectus before us,鈥� says Sikora. 鈥淭he conclusion suggests that these viruses almost certainly have been around even before the emergence of modern humans in some way, and have been infecting us since then.鈥�

But Pepperell is sceptical about this finding. 鈥淭he signal gets scrambled when organisms reshuffle their DNA, when they recombine,鈥� she says 鈥� and adenovirus C does that a lot.

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