Quotes About Selection

Adoption and contraception, like reading, mathematics, and stress-induced illness, are products of an animal that is living in an environment radically different from the one in which its genes were naturally selected.

It is these phenotypic effects that we see as adaptations to survival. When we ask whose survival they are adapted to ensure, the fundamental answer has to be not the group, nor the individual organism, but the relevant replicators themselves.

A gene is defined as any portion of chromosomal material that potentially lasts for enough generations to serve as a unit of natural selection.

The gene is a long-lived replicator, existing in the form of many duplicate copies. It is not infinitely long-lived. Even a diamond is not literally everlasting, and even a cistron can be cut in two by crossing-over. The gene is defined as a piece of chromosome which is sufficiently short for it to last, potentially, for long enough for it to function as a significant unit of natural selection.

How did ears get their start? Any piece of skin can detect vibrations if they come in contact with vibrating objects. This is a natural outgrowth of the sense of touch. Natural selection could easily have enhanced this faculty by gradual degrees until it was sensitive enough to pick up very slight contact vibrations. At this point it would automatically have been sensitive enough to pick up airborne vibrations of sufficient loudness and/or sufficient nearness of origin

superstitions and other non-factual beliefs will locally evolve – change over generations – either by random drift or by some sort of analogue of Darwinian selection, eventually showing a pattern of significant divergence from common ancestry.

Most of the replicators in the world have won their place in it by defeating all available alternative alleles. The weapons with which they won, and the weapons with which their rivals lost, are their respective phenotypic consequences

This is a subtle, complicated idea. It is complicated because the 'environment' of a gene consists largely of other genes, each of which is itself being selected for its ability to cooperate with its environment of other genes.

The genotype may be a 'physiological team', but we do not have to believe that that team was necessarily selected as a harmonious unit in comparison with less harmonious rival units. Rather, each gene was selected because it prospered in its environment, and its environment necessarily included the other genes which were simultaneously prospering in the gene-pool. Genes with complementary 'skills' prosper in each others' presence.

The earliest form of natural selection was simply a selection of stable forms and a rejection of unstable ones.

It is fundamental to the idea of a replicator that when a mistake or 'mutation' does occur it is passed on to future copies: the mutation brings into existence a new kind of replicator which 'breeds true' until there is a further mutation

I am, indeed, quite sympathetic towards the idea that human culture provides a new milieu in which an entirely different kind of replicator selection can go on.

From the viewpoint of this book an animal artefact, like any other phenotypic product whose variation is influenced by a gene, can be regarded as a phenotypic tool by which that gene could potentially lever itself into the next generation.

In principle, we may consider any portion of chromosome as a potential candidate for the title of replicator.

In that case there must have been genes controlling variation in caddis houses, for selection cannot produce adaptations unless there are hereditary differences among which to select.

Natural selection may usually be safely regarded as the differential survival of replicators relative to their alleles.

Once the vital ingredient—some kind of genetic molecule—is in place, true Darwinian natural selection can follow, and complex life emerges as the eventual consequence.

This, then, is our candidate replicator. But a candidate should be regarded as an actual replicator only if it possesses some minimum degree of longevity/fecundity/fidelity (there may be trade-offs among the three).

But if we set selection pressures on one side, we can say something about the half-life of a replicator on the basis of its length alone. If the stretch of chromosome we choose to define as our replicator of interest is long, it will tend to have a shorter half-life than a shorter replicator, simply because it is more likely to be broken by crossing-over. A very long portion of chromosome ceases to deserve the title of replicator at all.

a group, such as a species or a population within a species, whose individual members are prepared to sacrifice themselves for the welfare of the group, may be less likely to go extinct than a rival group whose individual members place their own selfish interests first. Therefore the world becomes populated mainly by groups consisting of self-sacrificing individuals. This is the theory of 'group selection'

It is widely admitted that serious error follows from the uncritical assumption that adaptations are for the good of the species.

Germ-line replicators, then, are units that actually survive or fail to survive, the difference constituting natural selection.

replicators. Now they go by the name of genes, and we are their survival machines.

It is the effects on the world of successful active germ-line replicators that we see as adaptations.