Who Were The First Americans?

(8 of 8)

ARCHAEOLOGY Skeletons like Kennewick Man are rare. More often scientists study and date other indications of human activity -- remains of butchered animals, stone tools, spear points or even bits of burned charcoal. Unfortunately, such artifacts may never be found along coastal migration routes -- they're now under water

GENETICS Scientists use markers in DNA samples from indigenous peoples in North and South America to figure out when populations diverged from each other. DNA comparisons suggest the first Americans may have diverged from groups in the Lake Baikal area of what is now Russia as early as 26,000 years ago

LINGUISTICS By studying native words and grammar, scientists can establish links and infer the amount of time required for different languages to evolve from a common origin. As of 1492, there were an estimated 1,000 languages in the Americas that may have developed from the original migrants

Migration milestones

• 30,000 B.P.* Beginning of last North American ice age. Mitochondrial-DNA studies indicate the earliest possible migration

• 25,000 Approximate opening of Bering land bridge between Asia and North America • 20,000 Earliest migration date, according to Y-chromosome studies • 15,000 Evidence of humans in South America Glacial melting floods Bering land bridge • 10,000 End of last ice age in North America Kennewick Man lives in Pacific Northwest • 5,000 Dawn of Central American cultures such as Olmec and Maya • Present

*Dates are in radiocarbon years "before the present," a scientific standard meaning "before 1950"