If as is accepted that humanoid life started on the plains of Africa, how did humans get to the Americas.?

Both DNA evidence and archaeological findings indicate that humans migrated from Asia to Alaska during the last Ice Age (which ended about 10,000 years ago.) During the Pleistocene Ice Age there was so much ocean water locked up in continental glaciers that the sea level was up to 100s of feet' lower in some areas than it is today. What is now the sea floor between Siberia and Alaska was exposed and you could easily walk across between the continents. The same was true of what is notw the English Channel between England and France -- those two regions were connected by dry land.

It is highly possible North Asian hunting and gathering groups followed along the north Pacific coastline, hunting marine mammals and gathering the plentiful foodstuffs found along the shores, workinng their way from Alaska down to what is now the west coast of the US and down along Mexico to South America over thousands of years, We are not yet certain how early these migrations started, but it was likely close to at least 20,000 years ago since we have found remarkable evidence of people in South America as early as 14,800 years ago (Monte Verde in southern Chile).

A good book on the subject is New World Archaeologist Jim Adovasio's book "The First Americans: in Search of Archaeology's Greatest Mystery". (full disclosure: Adovasio was my prof at university -- brilliant guy and he has found some of the earliest human evidence in the Americas at Meadowcroft Shelter in PA).

BTW, this wikipedia entry has a good basic map showing the migrational patterns as we currently understand them. The Bradshaw Foundation also has a nice animated world map with all the stages of world human population.

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https://en.wikipedia.org/wiki/Recent_African_origi...

http://www.bradshawfoundation.com/journey/timeline...

(hit "play" on the Bradshaw link)

Humans crossed from Asia to the Americas via the Siberian land bridge, which thousands of years ago connected Siberia in Asia to Alaska in North America.

In the last ice age there was a large plan where the Baring straights are. You could have walked from London to Bogota without getting wet.

Most of it was by walking. Some distances could have been done in small boats.

It isn't accepted -_-

http://www.washington.edu/news/2013/05/14/dna-anal...