Did HIV Kill the Dinosaurs?

Scientists have known for a while that HIV has been around far longer than initially thought; for at least a century, rather than the 35 years we typically think of.  Now there's new evidence that an HIV precursor —  HIV-related retroviruses called lentiviruses — may date back as far as 60 million years ago, near the point when dinosaurs went extinct. 

So far the evidence suggests that these kinds of virus only affected mammals (in particular a distant relative of the Malayan flying lemur), but it's more fun to speculate that it caused the demise of the dinosaurs (or collaborated with a giant asteroid to wipe them out). It may also give us tremendous insight into modern efforts to eradicate the disease. 

"We hope that our findings will allow virologists to better understand how lentiviruses evolved and how their hosts developed defenses against them," said Daniel Elleder of the Czech Academy of Sciences, lead author of the study published in the online edition of Molecular Biology and Evolution.

The researchers sequenced lemur DNA, followed the genome of the lemur containing lentiviral remnants and reconstructed ancient viral genomes; ultimately uncovering the oldest lentivirus ever identified. According to the study, lentiviruses are known to cause a variety of chronic diseases, ranging from the deadliest form of HIV/AIDS among humans and neurological disorders among primates.

Of course, odds are that these lentiviruses had little to no effect on causing species to go extinct. Given that they've been around for eons, there's potential that some animals developed immunity to them over the millions of years of evolution. If researchers can pinpoint adaptations that successfully fought off these viruses, it could point to new avenues for treatments, vaccines, or even a cure.

There's also some hope that tracing retroviruses back to the time of the dinosaurs could spur more interest in researching early letiviruses. After all, dinosaurs have inspired decades of scientific study and endless public fascination; perhaps knowing an HIV-type virus existed alongside dinosaurs will lead to new research, innovative ways of looking at the disease, and surprising new discoveries.