This is CBSi on the world. I'm John Boucher with Dan Flores. His new book is

Wild New World, the epic story of animals and people in America. The Clovis

culture so-called because of where it was identified that tools

were suggestive of a developing culture, is important first to establish where the sites are and Dan's book wonderfully

gives us a map of what's been found so far. They're more defined.

And these are between around 13,000 years ago.

There's speculation that human beings,

as we, the modern human beings, were here before them.

But it's important to establish why Clovis matters.

Den, it's the tools, it's the hunting skills, it's the remains of the sites, is that why we

key on that

13,000 years ago? It really is all those all those things you mentioned

as you referred to we do believe, or pretty convinced, in fact, by a set of footprints found in southern

New Mexico just four or five years ago, that people did get here even before the glacial maximum 23,000 years ago, but it looks

as if their populations were really small and one of the reasons we think that is

because when the Clovis migration happens and it happens when the ice sheets in

North America

open sufficiently to allow an overland migration

out of Siberia into what is now Canada

and the lower 48 states of the US, when that happens, this migration takes place with such

rapidity that it implies that there's not really anyone in the way of us. There's not really anyone that's

slowing down this Clovis movement from all the way from Alaska to the tip of

...