Chickens and Dogs and Bears, Oh My (DNA)

Why did the chicken cross the road? We may never know. But since it did, and it carried its DNA, we can now say something about both chicken and human migration. Yes, using DNA to trace migration and history is not limited to just humans.

Brown bear on the move. Photo courtesy of National Geographic
Brown bear on the move. Photo courtesy of National Geographic.

A new paper on polar and brown bear DNA suggests that the two species are more distantly related to one another, than what mitochondrial DNA (mtDNA, inherited strictly from the mother) had suggested. “More extensive male than female movement in bears, and many other mammals, implies that males carry genetic material over greater geographic distances than females” suggest reviewers of a new article published in the journal Molecular Biology and Evolution. Arguably, the same behavior pattern occurs in humans. For example, scientists have long postulated that Genghis Khan’s Y chromosome DNA successfully “spread” across thousands of miles in Asia in a very short time.

Genographic Project scientists study such patterns in human genetic variation by looking at mtDNA, Y-Chromosome DNA (inherited by men purely from their father), and autosomal DNA (inherited from both parents).  They then use the patterns observed across the world, to tell a story about human ancestry, human migration, and human history.

Dogs ready to work. Photo courtesy of National Geographic.

Did you know that canine DNA is also being used to understand human history? Scientists have known for centuries that dogs were domesticated from the grey wolf. But when and how many times were wolves domesticated? by what cultures?  and how many different wolves were needed to create today’s dog breed diversity? The answers to these questions rest in dog DNA, and Genographic Project collaborators at Cornell University are hard at work answering these and many other questions about dogs and domestication in much the same way that the Genographic Project answers questions about your own personal migration story.

Chicken crossing the grass
Chicken crossing the grass. Photo courtesy of National Geographic.

So, next time you munch on chicken fingers think about what may have been the story of that tasty fried morsel. A series of articles by Genographic Project scientists, among others, have shown that chickens were domesticated early in human history (possibly 8,000 years ago) and transported for thousands of miles across the Pacific, Indian, and eventually the Atlantic Ocean. Since chickens cannot fly across oceans, similar genetic lineages found on opposite sides of an ocean indicate purposeful human transportation.  We know ancient sea-faring Polynesians had chickens, and we see archaeological remains of chickens in South America that predate European arrival there. So, did the chicken cross that vast blue watery road? Stay tuned, DNA may just hold the answer.


Meet the Author
Dr. Miguel Vilar is the Science Manager for National Geographic's Genographic Project. Miguel is also a molecular anthropologist and a science writer. His fieldwork has taken him to remote places throughout the South Pacific, East Africa, Mesoamerica, and the Caribbean. In the laboratory he researches the modern genetic diversity of human populations from Melanesia, Micronesia, North and Central America, and the Caribbean. Miguel has published in several anthropology and genetics journals, as well as popular science magazines.