Ancient HIV

We're learning more about the origins of the AIDS virus by studying monkeys on a small volcanic island off of West Africa.

The island, called Bioko, was attached to the African continent until rising waters cut it off at least ten thousand years ago. Since then, four of the six species of monkeys that evolved there have members that are infected with SIV.

SIV stands for simian immunodeficiency virus and is what scientists believe became HIV when the virus jumped to humans. Studies show the SIV in monkeys on Bioko and on the mainland are related, which means the virus is at least ten thousand years old.

Knowing this and how fast SIV mutates, scientists now believe all SIV strains across Africa diverged from a common ancestor between 32-thousand and 78-thousand years ago. That common ancestor, though unknown, may have crossed into simians millions of years ago.

Because of this long co-existence, the virus doesn't make monkeys very sick. But an infected monkey can carry a swarm of mutated SIV viruses to which humans were exposed.

It's likely SIV infected humans many times in history and one or more of these viruses turned into HIV. But before the colonization of Africa, infected hunters most likely died before the virus could spread.

The theory is HIV became established after European nations colonized Africa. They built roads to connect cities promoting urban migration, which then increased sexual contacts.

They also introduced syringes, which were often reused.

The latest figures show in 2008, over 33 million people were living with HIV world wide and 2 million died of AIDS. The sad fact is, despite the advances, more people are living with HIV today.

Hopefully, by continuing to study this virus, including its origin, we'll develop even more ways to fight the disease.