Letter: The more the better

Except for one thing: when a species goes extinct, we cannot just print another. Moreover, even if one accepts your analogy, it takes radical inflation for people to stop caring about the conservation of currency. As the value of money declines slightly year to year, people do not typically respond by throwing it away. Your examples of polar bears and raccoons in the Bahamas show that species recognition counts in a similar manner. Simply, the public values species more than other categories of diversity.

I like to dream of a world so full of diversity that the death of another species would be no great loss, or in which the difference between geographic variant and species would be less fateful. But it is just that, a dream. As it is, we are contributing to the greatest series of extinctions in the last 65m years, and likely condemning our closest relatives in the process. Our limited financial history provides no analogue for that.

Dr Charles Lockwood, UCL Anthropology

'The Economist'