Evolving the Alien: The science of extraterrestrial life by Jack Cohen and Ian Stewart, Ebury Press, 拢17.99, ISBN 0091879272 Reviewed by David Langford
JACK COHEN and Ian Stewart are scientists 鈥� a reproductive biologist and a mathematician respectively 鈥� who love science fiction, despite its frequently flawed depictions of alien biology. This lively work of popular science uses real and science-fictional examples of strange creatures to fuel speculation about life inhabiting other planets鈥� or even suns.
Several SF stories feature alien 鈥渘ecrogenes鈥�, for example. These die to reproduce, the infants eating their way out of the mother鈥檚 corpse. Implausible? Cohen and Stewart triumphantly produce a genuine cockroach whose eggs hatch in the ovaries. 鈥淚t is very dramatic to step on a Pycnoscelis and have its babies run out from the burst body all over your shoes.鈥�
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The authors are cheerful iconoclasts who dismiss the oversimplification of science as 鈥渓ies-to-children鈥�. They poke fun at Star Trek鈥檚 too-human aliens, but devise a plausible evolutionary path for its small furry tribbles.
They take vigorous exception to the case made by Peter Ward and Donald Brownlee, in Rare Earth (Springer Verlag, 2000) for the extreme rarity of life in the Universe, arguing that its assumptions are parochial 鈥� too closely based on life as we know it, while ignoring life not as we know it.
So which aspects of Earth鈥檚 life are parochial and which universal? Are penises likely on other planets? Is sex? Yes, the authors believe, offering a variety of reasons. But the alien equivalent of DNA is likely to be a surprise. Their favourite expected universal is 鈥渆xtelligence鈥�, the pooling of individual intelligence through cultural tools like books and the Internet. Alien visitors, if they ever show, will necessarily be extelligent.
Incidental treats include synopses of nearly 30 science fiction novels about extraterrestrial life, with illuminating or acerbic comments. Michael Crichton鈥檚 Jurassic Park is severely handled for its implausible genetics, while Robert Forward wins admiration for thinking outside the biological box in Dragon鈥檚 Egg to imagine ultra-fast nucleonic life on a neutron star.
Cohen and Stewart鈥檚 enthusiasm and gusto are infectious. Evolving the Alien is entertaining, provocative, and crammed with tasty facts and speculations about the one biosphere we know but still don鈥檛 wholly understand. As J. G. Ballard likes to say, the truly alien planet is Earth.