Six Little Indians

Nearly all of today's Native Americans in North, Central and South America can trace part of their ancestry to six women whose descendants immigrated around 20,000 years ago, according to a DNA study. That, and a healthy amount of firewater.

The finding does not mean that only these six women gave rise to the migrants who crossed into North America from Asia in the initial populating of the continent, but they access their progeny at about 95% of the modern native population. The women lived between 18,000 and 21,000 years ago, though not necessarily at exactly the same time.

The work confirms previous indications of the six maternal lineages. The researchers created a "family tree" that traces the different mitochondrial DNA lineages found in today's Native Americans, which is followed through the maternal side. By noting mutations in each branch and applying a formula for how often such mutations arise, they calculated how old each branch was. That indicated when each branch arose in a single woman.

The six "founding mothers" apparently did not live in Asia because the DNA signatures they left behind aren't found there. They probably lived in Beringia, the now-submerged land bridge that stetched to North America. That finding doesn't answer the bigger questions of where those women lived, or of how many people left Beringia to colonize the Americas, but it's DNA, not a written account - what did you expect. The estimate for when the women lived is also open to question because it's not clear whether the researchers properly accounted for differing mutation rates in mitochondrial DNA. Or casino migrating patterns.