Why Fish Don't Exist: A Story of Loss, Love, and the Hidden Order of Life

by Lulu Miller

And then there was that key point in On the Origin of Species. That crucial point that somehow both David and before him Francis Galton had missed. What does Darwin say is the best way of building a strong species, of allowing it to endure into the future, to withstand the blows of Chaos in all her mighty forms—flood, drought, rising sea levels, fluctuating temperatures, invasions of competitors, predators, pests? Variation. Variation in genes, and hence in behavior and physical traits. Homogeneity is a death sentence. To rid a species of its mutants and outliers is to make that species dangerously vulnerable to the elements. In nearly every chapter of Origin, Darwin hails the power of “Variation.” He marvels over how diverse gene pools are healthier and stronger, how intercrossing between different types of individuals gives more “vigor and fertility” to their offspring, how even worms and plants that can produce perfect replicas of themselves are equipped for sex, for introducing variety back into the gene pool. “How strange are these facts!” he cries. “How simply are these facts explained on the view of an occasional cross with a distinct individual being advantageous or indispensable!” “Diversify your genetic portfolio” would be another way of saying it. You never know which traits could prove useful as conditions change. Darwin even goes out of his way to warn against meddling. The danger, as he sees it, is the fallibility of the human eye, our inability to comprehend...