DNA furnishes an ever clearer picture of the multimillennial trek from Africa all the way to the tip of South America.

A development company controlled by Osama bin Laden’s half brother revealed last year that it wants to build a bridge that will span the Bab el Mandeb, the outlet of the Red Sea to the Indian Ocean. If this ambitious project is ever realized, the throngs of African pilgrims who traverse one of the longest bridges in the world on a journey to Mecca would pass hundreds of feet above the probable route of the most memorable journey in human history.

Fifty or sixty thousand years ago a small band of Africans—a few hundred or even several thousand—crossed the strait in tiny boats, never to return. The reason they left their homeland in eastern Africa is not completely understood. Perhaps the climate changed, or once abundant shellfish stocks vanished. But some things are fairly certain. Those first trekkers out of Africa brought with them the physical and behavioral traits— the large brains and the capacity for language— that characterize fully modern humans. From their bivouac on the Asian continent in what is now Yemen, they set out on a decamillennial journey that spanned continents and land bridges and reached all the way to Tierra del Fuego, at the bottom of South America. Read the rest of this entry »

Molecular biologists have completely sequenced the first dog genome. Understanding how genetics plays a role in canine diseases could lead to new treatments for diseases shared by humans, such as diabetes, epilepsy and cancer. Breeders could also soon be able to check the purity of pedigrees by sending dogs’ cheek swabs to the lab.

So, why are some dogs excellent ball chasers and others perfect for your lap? Inquiring minds want to know! A standard poodle named Shadow, was the first dog to have its genes mapped, but only 80 percent complete. Now we have 100 percent of a boxer.

“The boxer genome will help us get at the genes responsible for diseases and traits in dogs,” says Ewen Kirkness, a molecular biologist at The Institute for Genomic Research in Rockville, Md.

Dogs and humans share many of the same diseases, like diabetes, epilepsy and cancer. Mapping dog genes could be the chief tool in finding disease-causing genes in people, because Kirkness says the same genes will be responsible for similar diseases in humans.

Genes that cause disease in dogs are easier to find than in people. Mutations in a dozen different genes can cause human disease, almost impossible to find. In dogs, only one gene mutation can cause a disease, and that same mutated gene causes an identical disease in humans.

“Then we have a better handle on what is causing the disease in humans, also,” Kirkness says.

Studying dog families also helps get a better handle on their own health and help eliminate dog diseases. “Testing can be done by breeders to limit the passage of these mutations into future generations.” Having a genetic map may also mean owners of pure-bred dogs and mutts may soon be able to document which breeds their dogs come from by simply sending a cheek swab or blood sample to a genetics lab.