[milan kyuubi]

Spoiler for Hominid inbreeding left humans vulnerable to disease:

A lack of mates among human ancestors that lived million years ago has left modern humans more vulnerable to genetic disease, a new study suggests.

Researchers compared samples from the genomes of more than 1000 people with those of chimpanzees to see how much genetic mutation has occurred in the two species since they diverged from a common hominid ancestor, about six million years ago. They also made comparisons with another closely related pair of species, rats and mice.

They focused on portions of DNA close to protein-coding genes. These segments are thought to regulate the activation of these genes.

The researchers calculated that these stretches of human and chimp DNA contained approximately 140,000 non-advantageous mutations, higher than expected and well above the number of retained genetic mutations seen in rats and mice. The mutations occur naturally but make both chimps and humans more susceptible to diseases with a genetic basis, such as cancer.

The cliche has always been that in-breeding causes genetic diseases. A good example in history was the family prevalence of the genetic disease hemophilia in certain European royal families, who tended to marry other royals. Another example is the increased prevalence of genetic diseases such as Tay Sachs disease in certain Jewish populations, because they encouraged arranged marriages within the same ethnic population.