MrDarwin

From Researchers Trace the Ancestry of AIDS:

I have to wonder how research like this could ever proceed without an evolutionary basis:

1. new organisms (including quasi-living things like viruses) do not pop into existence from nowhere; they come from some other, pre-existing critter (thus the search for evidence that HIV existed before the epidemic was detected);

2. lineages of organisms change over time (thus the researchers knew to search for something that is similar, but not necessarily identical, to HIV);

3. lineages of organisms can split into two or more distinct lineages (thus the researchers knew that there might be more than 1 strain of HIV derived from a single source);

4. species that are closely related are more similar in their genetics and physiology than are distantly related species, and so parasites like viruses are most likely to cross over onto closely related species (thus the search for HIV in our closest relatives, chimpanzees and monkeys);

5. host organisms evolve over time to become resistant or immune to disease (thus the researchers looked at healthy chimpanzees and monkeys that showed no apparent signs of disease); and

6. species that have been exposed to such diseases for the longest time will show the greatest resistance or immunity to those diseases (thus monkeys and chimps don't get sick, but humans get very, very sick upon HIV infection)

MrDarwin

Washington Post coverage:

Ancestry of AIDS Virus Is Traced

I should probably add that this research suggested a non-Darwinian element: the combination of two related viruses into a single virus. However, cases of reticulate evolution have been documented before and are a wrinkle on, rather than a refutation of, Darwinian evolution. I suppose a creationist would say that all these viruses are still the same "kind".

RufusAtticus

How is virus recombination "non-Darwinian?"

ps418

This would be a good opportunity to repost the link to:

Metzker et al, Molecular evidence of HIV-1 transmission in a criminal case. PNAS 99,14292-14297.

The full text is now available for free.

Patrick