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, a DNA study suggests.

Those women left a particular DNA legacy that persists to today in about about 95 percent of Native Americans, researchers said.

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, said study co-author Ugo Perego.