Thursday, June 21, 2007

AIDS: It's Evolution's Fault

Usually, being more evolved than something else is a compliment. In the case of the HIV virus, it turns out evolution really left us hanging.

It has been known for some time primates have much greater resistance to HIV than humans. The disease is serious to primates, but it's more like the measles to them, whereas to humans, HIV is nearly 100% incurable and the human body is almost completely unable to mount any defense against the disease. Researchers from the Fred Hutchinson Cancer Research Center have announced they may know why.

HIV is a retrovirus, meaning that it injects it's DNA into healthy cells, the viral DNA hijacks the cells and turns it into a virus factory. In the process, pieces of viral DNA can become embedded in the normal DNA of the host. Over millions of years, the viral DNA can actually become a part of the host's normal DNA. When researchers sequenced chimp DNA several years ago, they found that one of the major differences between chimp and human DNA is that chimp DNA contains pieces of viral DNA, probably from an ancient retro-virus. A team of "paleoviroligists" put the pieces of the ancient virus' DNA back together and then tested the million-year-old plague on chimp tissue. As expected, the chimp tissue was highly susceptible to the virus.

The researchers also tried the virus out on cat tissue that had been infused with several important sections of human DNA that control the immune system and differ from the chimp immune system. The human genes prevented the virus from doing much of anything, providing almost total immunity from the ancient virus. This confirmed the hypothesis that humans developed an immunity to the ancient virus, while primates did not.

What was really surprising, however, was what happened when they put HIV into the human-esque tissues. The HIV ran rampant in the human tissues, until they switched the human gene for the primate one, which caused the tissue to fight HIV in the same way that primate tissues do.

So what does this mean? Besides being very interesting for people who study early human evolution, it means that humans today are susceptible to HIV because we evolved our way out of another virus millions of years ago. It also means that researchers have found exactly why monkeys' immune systems work so much better than ours when it comes to HIV.

We may have used evolution to dodge a bullet a couple million years ago, but it seems that even evolution can't save us from everything. You can read more about this at Scientific American or ScienceDaily.

Also, this is just one more piece of evidence that evolution isn't your friend and will turn on you if you give it the chance. If you don't want evolution to "naturally select" you for certain doom, I'd suggest checking out the new Creation Museum in Cincinnati, Ohio that shows you haw easy it is to find people who believe that humans and dinosaurs co-existed and other alternate theories to evolution. Good luck!

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