Forget the Klingons
- Evolving the Alien: The Science of Extraterrestrial Life by Jack Cohen and Ian Stewart
Ebury, 369 pp, £17.99, September 2002, ISBN 0 09 187927 2
- XTL: Extraterrestrial Life and How to Find It by Simon Goodwin and John Gribbin
Weidenfeld, 191 pp, £12.99, August 2002, ISBN 1 84188 193 7
In the middle of the 19th century the prevailing scientific view of the abyssal ocean held that it was a vast body of water with a uniform temperature of 4 °C. With no variation of temperature there could be no convection currents, hence no circulation of dissolved oxygen and suspended food particles. The abyss was stagnant, a body of water under massive pressure, barely warmer than freezing and utterly without light. Thus, reasoned the scientists (influenced, no doubt, by human physiology and the Book of Genesis), it could not conceivably support life. The Manx naturalist Edward Forbes coined the word ‘azoic’ to describe this self-evidently lifeless zone. By the 1870s he and other oceanographers were eating their words as improved sampling technology retrieved abundant evidence that, in cheerful defiance of human preconceptions, even the deepest abyss was teeming with life.
A cautionary tale, one might think, for scientists of the early 21st century engaged in planning space missions to find extraterrestrial life. Expressly shunning an anthropic approach, the authors of Evolving the Alien insist that the fledgling science devoted to discovering extraterrestrial life-forms should be known not as ‘astrobiology’ but as ‘xenoscience’. They are combative on this point, and so united that they frequently refer to themselves as ‘Jack&Ian’. To this winsome dyad the notion of astrobiology is limiting in that it stands for astronomy as seen from Earth plus Earth-style biology, so that its thinking is governed by anthropic concerns such as the search for ‘habitable zones’ elsewhere in our solar system, just as we once looked in the oceans. Jack&Ian is feistily scornful of ‘habitable zone’ thinking, partly because he knows how life constantly confounds human expectations of what is habitable and partly because he has in mind life-forms quite unlike terran creatures, with properly alien chemistries and biologies to match.
Most formative thinking about the genuinely alien has been done by science fiction writers, and Cohen and Stewart provide their own short SF story about how an unknown creature might perceive a Nasa probe sent in the near future to Europa, a satellite of Jupiter. (There are great hopes that life might be found in the ocean that is believed to lie beneath its frozen surface.) They also dot their text with plot summaries of thirty SF classics in order to illustrate their scientific points. Part of their task is to debunk popular misconceptions about what alien life-forms might be like. They are merciless with anthropomorphic nursery and cinematic imagery (ET and Star Trek), the fallacies underlying the cod science of Jurassic Park and the loony gospel of UFOs and alien abductions.
Since they start from a strictly Darwinian account of terrestrial evolution they can assert that however alien life-forms may turn out to look, there is virtually no possibility that they will resemble Homo sapiens. We can forget humanoids such as Mr Spock and the Klingons because Homo evolved under a uniquely changing series of terran conditions. What is more, even if evolution could be rerun, contingency would guarantee that next time around it would not follow the same path. Stephen Jay Gould’s book Wonderful Life, about the fantastic evolutionary dead-ends fossilised in Canada’s Burgess Shale, makes this point beautifully. We and other land vertebrates owe our eyes-above-nose-above-mouth features and our awkwardly intersecting windpipe-and-gullet arrangement to a lobe-finned fish that happened to make it ashore. (The bad design of this airway-cum-throat means that people occasionally choke to death, but too infrequently for the feature to have been deselected by evolution. A similar awkwardness can be seen in the bizarre mix-up of our genital and excretory organs.)
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[*] Granta, 240 pp., £12.99, August 2002, 1 86207 512 3.