The Gene: An Intimate History

by Siddhartha Mukherjee

it was evident that genetic variation was the norm, not the exception, in nature. American and European eugenicists insisted on artificial selection to promote human “good”—but in nature there was no single “good.” Different populations had widely divergent genotypes, and these diverse genetic types coexisted and even overlapped in the wild. Nature was not as hungry to homogenize genetic variation as human eugenicists had presumed. Indeed, Dobzhansky recognized that natural variation was a vital reservoir for an organism—an asset that far outweighed its liabilities. Without this variation—without deep genetic diversity—an organism might ultimately lose its capacity to evolve.