Why are there no lobsters on lands or bats at sea? The answer appears to be a biological version of beginner's luck

The principle of incumbency is widely applicable in biology and has important implications for our own relationships with the rest of the biosphere. By destroying or modifying most of the world's ecosystems and by exploiting most of the competitively superior animals and plants on land as well as in the sea, we humans are eliminating incumbents. This makes it even easier for the remaining species (many of which are often disparaged, perhaps unfairly, as "weeds" because of their ability to adapt to life in the disturbed environments we have fashioned) to spread to new habitats or regions. Now that humans are the most powerful of all incumbents, let's hope that we can govern wisely and compassionately.

Geerat J. Vermeij ("Why Are There No Lobsters on Land or Bats at Sea?" page 60) is a professor of geology at the University of California, Davis. Mollusks, living and extinct, are his first love. Praising their manageable size, varied textures, and great diversity, he says that "shells have just about everything a scientist could want." In 2000, Vermeij received the Daniel Giraud Elliot Medal from the National Academy of Sciences for "extracting major generalizations about biological evolution from the fossil record, by feeling details of shell anatomy that other scientists only see." Blind from age three, he is the author of A Natural History of Shells (Princeton University Press) and the autobiographical Privileged Hands: A Scientific Life (W. H. Freeman).

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