Did Humans Colonize the World by Boat?

From DiscoverMagazine.com by Heather Pringle  05.20.2008

Research suggests our ancestors traveled the oceans 70,000 years ago.

            Jon Erlandson at the University of Oregon looks at a dart head designed to lodge in the flesh of marine prey. Erlandson recently collected dozens of these from San Miguel 27 miles off the coast of California. Radiocarbon dating of shows that humans first landed on San Miguel at least 12,000 years ago. The dart head in my hand holds clues to the ancestry of those seafarers. Archaeologists have recovered similar items scattered along the rim of the North Pacific, and some have even been found in coastal Peru and Chile. The oldest appeared 15,600 years ago in coastal Japan. To Erlandson, it looks like a trail left by mariners who voyaged along the northern coasts of the Pacific Ocean from Japan to the Americas during the last Ice Age.

            Most scientists believed that Homo sapiens evolved as terrestrial hunters and gatherers and stubbornly remained so, trekking out of their African homeland by foot and spreading around the world by now-vanished land bridges. But that picture is badly flawed, due to the changes in sea level over time. Some 20,000 years ago, for example, ice sheets locked up much of the world’s water, lowering the oceans and laying bare vast coastal plains—attractive hunting grounds and harbors for maritime people. Today these plains lie beneath almost 400 feet of water, out of reach of all but a handful of underwater archaeologists.”

            New evidence even raises the possibility that our modern human ancestors may have journeyed by raft or simple boat out of Africa 60,000 to 70,000 years ago, crossing the mouth of the Red Sea. Our new understanding of climate and sea-level change sheds light on something that has long puzzled archaeologists: How did modern humans colonize the far reaches of the globe so quickly after their exodus from Africa? If Erlandson and his colleagues are right, it was a series of sea voyages and river crossings that brought our ancestors to alien lands, launching the greatest biological invasion of all time.