“There are species that retain their characteristics even in conditions that are relatively different from their natural ones; other species in similar circumstances instead become extinct; otherwise what takes place is racial mixing with other elements in which no assimilation or real evolution occurs. The result of this interbreeding closely resembles Mendel’s laws concerning heredity: once it disappears in the phenotype, the primitive element survives in the form of a separated, latent heredity that is capable of cropping up in sporadic apparitions, even though it is always endowed with a character of heterogeneity in regard to the superior type.”

“Man wants to see nature and evolution as separate from human activities. There is a natural world, and there is man. But man also belongs to the natural world. If he is a ferocious predator, that too is part of evolution. If cod and haddock and other species cannot survive because man kills them, something more adaptable will take their place. Nature, the ultimate pragmatist, doggedly searches for something that works. But as the cockroach demonstrates, what works best in nature does not always appeal to us.”

“I think it inevitably follows, that as new species in the course of time are formed through natural selection, others will become rarer and rarer, and finally extinct. The forms which stand in closest competition with those undergoing modification and improvement will naturally suffer most.”

“Then there was the gray of human habitation. The blue places were turning brown, the yellow places to dust, the green places to smoke and ashes. Each time one of the animals disappeared--they went by species or sometimes by organizations of species, interconnected--it was as though all mountains were gone, or all lakes. A certain form of the world. But in the gray that metastasized over continents and hemispheres few appeared to be deterred by this extinguishing or even to speak of it, no one outside fringe elements and elite groups, professors and hippies, small populations of little general importance. The quiet mass disappearance, the inversion of the Ark, was passing unnoticed.”

“When faced with a radical crisis, when the old way of being in the world, of interacting with each other and with the realm of nature doesn't work anymore, when survival is threatened by seemingly insurmountable problems, an individual life-form -- or a species -- will either die or become extinct or rise above the limitations of its condition through an evolutionary leap.”

“In the United States both scholars and the general public have been conditioned to viewing human races as natural and separate divisions within the human species based on visible physical differences. With the vast expansion of scientific knowledge in this century, however, it has become clear that human populations are not unambiguous, clearly demarcated, biologically distinct groups. Evidence from the analysis of genetics (e.g. DNA) indicates that most physical variation, about 94%, lies within so-called racial groups. Conventional geographic "racial" groupings differ from one another only in about 6% of their genes. This means that there is greater variation within "racial" groups than between them. In neighboring populations there is much overlapping of genes and their phenotypic (physical) expressions. Throughout history whenever different groups have come into contact, they have interbred. The continued sharing of genetic materials has maintained all of humankind as a single species.”