This is CBS Eye on the World. Here's John Batchler.

It is a great joy to welcome the author Thomas Halliday, a paleontologist and an evolutionary

biologist. His new book, Other Lands, a journey through Earth's extinct worlds. Thomas

takes us backwards in time to what we know about the beginning of life as we understand

it is evolved over the 500 million plus years that we've watched multicellular life, congeal

and cooperate. We begin, however, in something where homo sapiens is present. It's called

the place to seem and it's a matter of going to a place we know very well, which is Alaska.

But this is a time when these sea levels are much lower and there is a connection to

Siberia called Beringia. Thomas, congratulations. You write beautifully. And sometimes your

metaphors are so convincing. I don't want to use the scientific name. So what is the mammoth

step and what was happening there 20,000 years ago? Good evening, Thomas. Good evening.

Yes, the mammoth step was during much of the place to see the largest ecosystem on the

planet. It's a grassland which is managed by big herbivores. So mammoths as the name suggests,

but also things like woolly rhinos and muscoxins and bison and relatives of some of the creatures

that are still around today like, like heribu and so on. But it's fetched from Western Europe

all the way through what is now Russia across, as you say, this connection between Siberia and North

America known as Beringia and then into Alaska and the Yukon. And it was not a sort of a holy

identical landscape across the entirety of its length. Obviously you've got a bit of local

variation going on here and there, but broadly it's this sort of gray cold grass dominated

ecosystem which is managed by these large herbivores. And yes, the book is opens in a

chapter set 20,000 years ago, which is during the height of the last time that we had these ice

feet advance from the poles. And at a time when Alaska was unlike today and are relatively

...