The subtitle is tough to swallow -- "Island Biogeography in an Age of Extinctions" -- but the book itself (The Song of the Dodo) is remarkably readable, explaining fascinating and difficult concepts in simple language. You come to see the give and take and evolution of evolutionary theory right up to the controversies of today, where theories which seem quite similar and are built on the same base of scientific evidence can lead to different public policy stands, with enormous consequences for natural habitats and the species that live there.
But what is uppermost on my mind is not what I read there, but what the reading prompting me to think about. I had not before realized that evolution depends on the existence of isolated populations. Only if members of a species become isolated from one another for extended periods of time -- for instance by an island splitting off from a continent -- will a new species evolve, adapted to the new physical circumstances. As long as there is a common gene pool, variations will be relatively minor, mutations will be drowned, and the species will remain relatively unchanged for vast periods of time. So, in this context, there is evolutionary value to an instinct for colonization -- for breeding groups migrating vast distances and setting up residence in a new area, with no expectation of ever returning or communicating with the original group. (This is my interpolation.)
Presume that there is a planet in a distant star system that has reached the pinnacle of advanced civilization. The entire planet is settled. The peoples are at peace with one another, and have arrived at a stable and sustainable population level. (I'm thinking in terms of the game "Civilization" carried through to its limit.) Thanks to their advanced technology, they have the capability for space travel. But there are no other habitable planets without reasonable distance. So their space travel has been limited to scientific, exploratory missions.
Say the rulers of this planet arrived at the kind of understanding of the evolutionary process shown in this book. Then they might realize that despite their accomplishments, their civilization and their genes are are great risk. Because their species on that planet represents a single gene pool, there are no significant variations and there will be no further evolution. Hence they are at risk of a single unpredictable natural catastrophe wiping them out entirely (since none of them would have evolved variant biological characteristics enabling survival.)
Then they might well arrive at the conclusion that they should send forth space-going colonists in all directions, with no desire or expectation that they would ever return. Then their space-going colonies and eventually the colonies their descendants might spawn on planets many light years away would naturally evolve. So hundreds of thousands of years hence there would be not just one species on one planet, but rather dozens or hundreds of species that had evolved from that single species, scattered through the universe and ensuring the perpetuation of the genes.
With this scenario in mind (and not going into the enormous technical difficulties involved in any kind of space colonization), it occurred to me that the likelihood that Earth will come in contact with intelligent beings from elsewhere in the universe is far greater than I would have otherwise believed.
Before, based just on the kinds of motivation I was familiar with, it seemed extremely unlikely that in the vastness of space there would occur such an encounter. Given the vast distances involved and the limitation of the speed of light, conquest made no sense at all, for there would be nothing gained by conquering another world several lifetimes away from your own. And the notion of colonization to reduce population pressures made no sense because 1) a society that advanced would certainly have found the means to control population growth and 2) the numbers of individuals who could be put on an Ark-like space ship would be very limited in comparison with the total population and hence would provide minimal population relief.
But with this new motivation -- preservation of the genes by creating opportunities for continued evolution -- I could easily imagine any and every advanced planet in the universe sending forth colonizing ships in every direction.
NB -- in this scenario, the limit of speed of light and the vast distances between stars with habitable planets have evolutionary value.
Other book reviews by Richard Seltzer
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