Of all the things I am not very good at, living in the real world is perhaps the most outstanding. - Bill Bryson

The Smokies seem to be in the process of losing most of their mussels. The National Park Service actually has something of a tradition of making things extinct. Bryce Canyon National Park is perhaps the most interesting—certainly the most striking—example. It was founded in 1923 and in less than half a century under the Park Service’s stewardship lost seven species of mammal—the white-tailed jackrabbit, prairie dog, pronghorn antelope, flying squirrel, beaver, red fox, and spotted skunk. Quite an achievement when you consider that these animals had survived in Bryce Canyon for tens of millions of years before the Park Service took an interest in them. Altogether, forty-two species of mammal have disappeared from America’s national parks this century.

I know this goes without saying, but Stonehenge really was the most incredible accomplishment. It took five hundred men just to pull each sarsen, plus a hundred more to dash around positioning the rollers. Just think about it for a minute. Can you imagine trying to talk six hundred people into helping you drag a fifty-ton stone eighteen miles across the countryside and muscle it into an upright position, and then saying, 'Right, lads! Another twenty like that, plus some lintels and maybe a couple of dozen nice bluestones from Wales, and we can party!' Whoever was the person behind Stonehenge was one dickens of a motivator, I'll tell you that.

As we parted at the Natural History Museum in London, I asked Richard Fortey how science ensures that when one person goes there's someone ready to take his place.

He chuckled rather heartily at my naiveté. 'I'm afraid it's not as if we have substitutes sitting on the bench somewhere waiting to be called in to play. When a specialist retires or, even more unfortunately, dies, that can bring a stop to things in that field, sometimes for a very long while.'

And I suppose that's why you value someone who spends forty-two years studying a single species of plant, even if it doesn't produce anything terribly new?'

'Precisely,' he said, 'precisely.' And he really seemed to mean it.