Imagine standing on a stretch of land that today no longer exists.

We're around 12,000 years ago at the very end of the last Ice Age.

To the west, a glacier rises higher than any mountain you've ever seen,

a wall of ice stretching from horizon to horizon. To the east, a vast plain spreads before you.

No ice, this is land, dotted with grasses, scattered spruce trees, and herds of animals

unlike anything alive today. On this plane, off in the far distance, a small group of human beings, people, are moving across this barren landscape,

following a route their ancestors charted generations earlier.

These are skilled, resilient people, deeply connected to the land.

Land that around them is changing faster than any living person can remember.

The ice is melting. Rivers are shifting. Coastlines are flooding. Entire ecosystems are rearranging

themselves. And the animals, these giant animals they've relied on for millennia, are growing

scarcer and new plants and forests are taking

their place.

These people don't realize it, of course, but they're living through one of the great turning

points in human and environmental history, a moment that will reshape the land, the wildlife,

and the future of the American continents.

Good day. You're listening to American History Hit. Nice to be with you. I'm Don Wildman.

In scholarly circles, there's a broad school of thinking called determinism.

It's in all disciplines, goes way back. The general theory that any event in history is the inevitable consequence of factors in motion preceding it.

Pretty sensible, straightforward, nothing happens in a vacuum.

But many consider this simplistic and convenient thinking, where, nothing happens in a vacuum. But many consider this simplistic

and convenient thinking, where, especially in the history of human development, matters

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