27 janvier 2017

Le prix élevé des croisements de nos ancêtres

Il semble de plus en plus certain que nos ancêtres ont eu des descendants avec des Néandertaliens. Il semblerait toutefois que le prix à payer pour ces escapades préhistoriques soit plutôt élevé.

Extraits de la nouvelle:

The legacy of interbreeding is very real and seems to explain quite a few modern ailments, and some rather nasty diseases as well.

Neanderthal DNA is associated with an increased risk of developing skin corns and callosities, mood disorders and depression, overweight and obesity, upper respiratory and urinary tract infections, incontinence, hardening of the arteries and even smoking.

Then there’s those immediate risks that come with casual sex with your own, or in this case, another species.

Like catching a parasite such as body lice, or worse still, contracting a sexually transmitted infection.

Body lice are parasites that evolve in tandem with their hosts. Other mammals have them, but human lice species are unique to us, and spread through close contact such a sex.

A person can be infested with thousands of these blood suckers, each insect biting five times a day.

But worse, they also carry deadly bacteria. Diseases like endemic typhus are carried and spread by body lice and are said to have caused more deaths than all the wars in history put together.

Genetic studies of body lice suggest that one of the two species that infects us today evolved more than a million years ago, in association with another human-like species.

What’s the implication here? Yet again, we probably got body lice because our ancestors engaged in the pants-off dance off with an evolutionary cousin.

Now a new study has found that a particular human papillomavirus (HPV16), one of the most common sexually transmitted infections with 14 million new cases each year in the US alone, was also inherited from the Neanderthals.

The amazing diversity of HPV16 variants across Asia and Europe - compared with low diversity in Africa - has long puzzled researchers.

You’d expect the opposite situation because we evolved in Africa and presumably carried HPV16 out with us when we left there 100,000 years ago or more.

This new study solves the mystery by showing that modern humans brought only a small subset of HPV16 variants out of Africa, picking up most of the other strains after they (ah, we) bonked the Neanderthals.

Technically, this is known as a host-shift, where sexual contact with archaic populations led to the transmission of new variants of HPV16 to us.

With time, even more diversity was generated as modern humans spread across the rest of the Old and New Worlds.

High risk human papillomaviruses are a serious global health issue. They’re associated with around 5 percent of all cancers worldwide.

The choice our ancestors made to interbreed with the Neanderthals, Deniosvans and probably numerous other archaic cousins have left us with profound legacies that we’re only beginning to learn about.

What else might they have done that had profound consequences for us today?

À lire également:

Nouvelle preuve de croisement entre humains et Néandertaliens

Les Néandertaliens ne sont pas nos ancêtres

Cannibales, les Néandertaliens?

2 commentaires:

fylouz a dit…

D'où l'intérêt de mettre une capote.

Prof Solitaire a dit…

Celles en cuir d'élans n'étaient pas très confortables à l'époque! ;-)