Imagine there was not one species of human…but many. One stronger. One smaller. All different, but closely related.

Around 40,000 years ago, that’s exactly how it was. Homo sapiens – us – shared Earth with several other Homo species. Then those other ones went extinct, and we carried on. The sole survivors.

Why? Because we could better adapt to changing climates. And that’s because of a few key qualities.

First, we had more flexible diets. We could eat large animals or small. Fish, fowl, or foraged plants.

One reason we could do that, is we also had better control of fire. Which allowed us to cook those various foods to extract more nutrients and calories.

We also had better tools, to more effectively butcher animals, and importantly, sew their hides into fitted clothing and covering for shelters -- which allowed us to endure the bitter cold of the Ice Age.

And because of those things, we were mobile. We could take our tools, clothing and shelters, flexible diets and fire to cook them, to different regions as climate patterns changed.

We also had dogs, for hunting. And to hear that amazing story, look it up on EarthDate.org.

But there’s one more Homo sapiens trait that may have mattered most of all. We had advanced language, to communicate the knowledge of all these things, to cooperate and collaborate, and to build the social cohesion required to weather difficult environments.