Why Evolution Is True

by Jerry A. Coyne

So what is “Darwinism”?1 This simple and profoundly beautiful theory, the theory of evolution by natural selection, has been so often misunderstood, and even on occasion maliciously misstated, that it is worth pausing for a moment to set out its essential points and claims.

The process is remarkably simple. It requires only that individuals of a species vary genetically in their ability to survive and reproduce in their environment. Given this, natural selection—and evolution—are inevitable.

So natural selection does not yield perfection—only improvements over what came before. It produces the fitter, not the fittest.

Nothing in biology makes sense except in the light of evolution. —Theodosius Dobzhansky

“Ontogeny recapitulates phylogeny.” This means that the development of an organism simply replays its evolutionary history. But this notion is true in only a limited sense.

“Any event that is not absolutely impossible ... becomes probable if enough time passes.”

And while I said that natural selection acts, this is not really accurate. Selection is not a mechanism imposed on a population from outside. Rather, it is a process, a description of how genes that produce better adaptations become more frequent over time.

Es una descripcion de un sistema realimentado que ocurre naturalmente.

Richard Dawkins provided the most concise definition of natural selection: it is “the non-random survival of random variants.”

Sexual selection is simply selection that increases an individual’s chance of getting a mate. It’s really just a subset of natural selection, but one that deserves its own chapter

Some species are monogamous, with both males and females providing parental care. Evolution can favor monogamy if males have more offspring by helping with child care than if they abandon their offspring to seek more matings. In many birds, for example, two full-time parents are required: when one goes off to forage, the other incubates the eggs. But monogamous species are not that common in the wild. Only 2 percent of all mammal species, for instance, have this type of mating system.

In it Mayr recounted a striking fact. When he totaled up the names that the natives of New Guinea’s Arfak Mountains applied to local birds, he found that they recognized 136 different types. Western zoologists, using traditional methods of taxonomy, recognized 137 species. In other words, both locals and scientists had distinguished the very same species of birds living in the wild. This concordance between two cultural groups with very different backgrounds convinced Mayr, as it should convince us, that the discontinuities of nature are not arbitrary, but an objective fact.37

The biological species, then, is the unit of evolution—it is, to a large extent, the thing that evolves.

A polyploid can arise simply by doubling all of the chromosomes of a single species—a process called autopolyploidy.

Commercial bananas are sterile hybrids between two wild species, having two sets of chromosomes from one species and one set from the other. Those black specks in the middle of your banana are, in fact, aborted plant ovules

is one sexually reproducing polyploid mammal, the curious red viscacha rat of Argentina.

Like theology, paleoanthropology is a field in which the students far outnumber the objects of study.

:)