Kill off the sacred bear. Kill off the ancestral crocodile. Kill off the myth-wrapped tiger. Kill off the lion. You haven't conquered a people, or their place, until you've exterminated their resident monsters.

There was a very important superintendent of Yellowstone, a man who was involved in the founding of the National Park Service itself, Horace Albright. And he became superintendent, which is the boss of Yellowstone Park, in 1919 - from 1919 to 1929. Later, he was director of the park service itself. Albright embraced the idea that in order for the national parks - and Yellowstone in particular - to have support from the American people and from politicians, there needed to be wildlife as spectacle.

Heatstroke is an important and useful addition to the library on climate change, bringing insights from deep-time ecological research to help illuminate the dire forecasts of which we're already so aware.

Nor are we the culmination of evolution, except in the sense that there has never been another species so bizarrely ingenious that it could create both iambic pentameter and plutonium.

What do we measure when we measure time? The gloomy answer from Hawking, one of our most implacably cheerful scientists, is that we measure entropy. We measure changes and those changes are all for the worse. We measure increasing disorder. Life is hard, says science, and constancy is the greatest of miracles.

I used to read only fiction. Now I don't read much, only occasionally, such as a Cormac McCarthy or a Jim Harrison novel.

The elk are the most abundant large herbivores in the Yellowstone ecosystem. There are thousands and thousands of them. They migrate in and out. And those migration routes need to stay open.