Quotes About Evolution

Replicators may be classified in two ways. They may be 'active' or 'passive', and, cutting across this classification, they may be 'germ-line' or 'dead-end' replicators.

This is a book about the positive evidence that evolution is a fact. It is not intended as an anti-religious book. I have done that, it's another T-shirt, this is not the place to wear it again

Gaps, by default in the mind of the creationist, are filled by God.

algorithm of natural selection has generated a machine capable of internalizing the algorithm, setting up a model of itself – and much more – in microcosm inside the human skull.

A further important point is that Maynard Smith was seeking the 'best' strategy in only a special sense. In fact he was seeking an 'evolutionarily stable strategy' or ESS.

Evolution is the process by which some genes become more numerous and others less numerous in the gene pool.

A germ-line replicator (which may be active or passive) is a replicator that is potentially the ancestor of an indefinitely long line of descendant replicators. A gene in a gamete is a germ-line replicator. So is a gene in one of the germ-line cells of a body, a direct mitotic ancestor of a gamete.

The ESS has been rigorously defined (Maynard Smith 1974), but it can be crudely encapsulated as a strategy that is successful when competing with copies of itself.

If a program or strategy is successful, this means that copies of it will tend to become more numerous in the population of programs and will ultimately become almost universal. It will therefore come to be surrounded by copies of itself. If it is to remain universal, therefore, it must be successful when competing against copies of itself, successful compared with rare different strategies that might arise by mutation or invasion.

When we talk of a program as 'doing better' or as being 'successful' we are notionally measuring success as capacity to propagate copies of the same program in the next generation: in reality this is likely to mean that a successful program is one which promotes the survival and reproduction of the animal adopting it.

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.

The point about recurrent reproduction life cycles, and hence, by implication, the point about organisms, is that they allow repeated returns to the drawing board during evolutionary time.

Firstly, we could ban reproduction before a certain age, say forty. After some centuries of this the minimum age limit would be raised to fifty, and so on. It is conceivable that human longevity could be pushed up to several centuries by this means.

A DNA molecule in the germ-line of an individual who happens to die young, or who otherwise fails to reproduce, should not be called a dead-end replicator. Such germ-lines are, as it turns out, terminal. They fail in what may metaphorically be called their aspiration to immortality. Differential failure of this kind is what we mean by natural selection.

As I said, the active/passive distinction cuts across the germ-line/dead-end distinction. All four combinations are conceivable.

The integrated multicellular organism is a phenomenon which has emerged as a result of natural selection on primitively independent selfish replicators. It has paid replicators to behave gregariously. The phenotypic power by which they ensure their survival is in principle extended and unbounded. In practice the organism has arisen as a partially bounded local concentration, a shared knot of replicator power.

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.

To the extent that active germ-line replicators benefit from the survival of the bodies in which they sit, we may expect to see adaptations that can be interpreted as for bodily survival.

To the extent that active germ-line replicators benefit from the survival of bodies other than those in which they sit, we may expect to see 'altruism', parental care, etc.

the God of the Gaps' strategy condemned by the theologian Dietrich Bonhoeffer. Creationists eagerly seek a gap in present-day knowledge or understanding. If an apparent gap is found, it is assumed that God, by default, must fill it. What worries thoughtful theologians such as Bonhoeffer is that gaps shrink as science advances, and God is threatened with eventually having nothing to do and nowhere to hide. What worries scientists is something else.

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

We should not seek immortality in reproduction.

Living bodies are machines programmed by genes that have survived.