

Two Strains of H.I.V. Cut Vastly Different Paths - evilsimon
http://www.nytimes.com/2015/03/02/science/two-strains-of-hiv-cut-vastly-different-paths.html

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mootothemax
The startling thought is that SIV has existed for a long, long time - I've
read that it's tens of thousands of years old - and yet HIV only emerged in
the last century or so.

The only explanation that makes sense to me is that HIV _has_ emerged
previously, but only in dead-end strains that have very low infectivity,
rather like the HIV-1 groups N and P mentioned in the article. Whilst it makes
sense to me, I have a feeling that it _can 't_ be right; seems a bit too easy
or convenient to explain.

Are we victims of a million-to-one chance mutation, but a chance that become
steadily more likely as time progressed?

Further, is it just a fact of life that we can - and _should_ \- expect
another HIV-level-of-infection virus to emerge in the future?

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gort
> The only explanation that makes sense to me is that HIV has emerged
> previously, but only in dead-end strains that have very low infectivity,
> rather like the HIV-1 groups N and P mentioned in the article.

Or that modern innovations like transportation and so on made it possible for
it to spread before it died out.

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Grazester
Exactly. This why Ebola hadn't spread the way it did until now. It was
isolated to small remote villages.

