" 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. "

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