There is radiocarbon dating of bone tools, found in the Canadian Yukon, dating to 22,000 B.C. These tools are evidence of the human presence in that area at that time. However, the land as far south as the St. Lawrence River and Lake Erie was still covered by glacial ice 10,000 years ago, and thus the first inhabitants probably did not move into the southwestern Ontario area until several thousand years later.

The Yukon was not covered by ice 22,000 years ago and these found tools provide a rationale for the most widely accepted theory of how and when people moved into North America, the (1) Land Bridge Theory.

The Human Migration map, above, shows that ice covered the Rocky Mountains Range along the west coast with a narrow melted gap between the ice sheet covering all of Greenland and North America from Hudson Bay to Georgian Bay, Lake Ontario and the St. Lawrence River.

The red arrows show the path of human migration from Asia (top left) across a ‘land bridge’ formed by the weight of ice pushing down on the earth’s tectonic plates and causing land to push up above water level. (Bering Strait) After the ice melted over thousands of years, the ‘land bridge’ sank under to water forming Bering Strait between Asia and North America.

The Land Bridge theory uses the information that humans living in Asia had originally migrated from southern and eastern Africa to the middle east, across Asia to the Siberia region, and thus across the ‘land bridge’ into North, Middle and South Americas. The exact dates are subject to change as more archaeological data is discovered.

As more evidence develops, additional theories arise: The (2) Coastal route theory says that some people may also have come from Asia by boat about 20-15,000 years ago; the (3) Europe route theory says that some people may also have come from Europe via Newfoundland to the eastern and southern area of the United States about 24 – 18,000 years ago.