LIFE ELSEWHERE; IF AND WHAT or THE POSSIBILITY OF LIFE ON OTHER PLANETS
Arguments and evidence about alien life has been based in chemistry and naive biological philosophies; evolutionary biology can tell us the likelihoods of biological innovations on this planet, and we can use comparable argument about other evolutions. Life, and indeed intelligence, is common - but the peculiarities of our evolutionary history, like airway-crossing-foodway, and our kind of excretory/reproductive mix-up, will not be found elsewhere; they are parochial. Knees and elbows are also Parochial in (pentadactyl) detail, but joints-in-the-limbs are Universal; so are photosynthesis, life on land, flight and many other multiple inventions here. The argument to intelligence as a Universal is interesting (takes the mind to new places) and has ethical consequences. This came out as a piece in the Xmas New Scientist 1991.