There are several lessons one might draw from the (solved) mystery of the shrinking sheep of the Isle of Hirta. There is the obvious, and alarming, lesson that climate change is advancing rapidly.
There is the lesson that, despite the carping of the philistines, it is worthwhile to fund scientists to perform outlandish tasks such as measuring the size of the bellies of wild sheep on remote Scottish islands.
Finally, there is the lesson that, in nature, bigger does not necessarily mean better. Under the terms of classic evolutionary theory, these sheep should have been getting fatter, not thinner. But evolution, as we now see, is a rather more subtle and complex process than that. And it can also work faster than scientists anticipated.
But one intriguing question remains to be answered: will we humans, for once, follow where the sheep lead?