Quotes About Replicator

Evolution itself embodies an ongoing exchange of information between organism and environment .... The gene has its cultural analog, too: the meme. In cultural evolution, a meme is a replicator and propagator — an idea, a fashion, a chain letter, or a conspiracy theory. On a bad day, a meme is a virus.

Substitute Malaysia or Mexico for the replicator, and make Palo Alto the Bridge, and bingo: RIGHT NOW = STAR TREK.

For me, the level at which natural selection causes the phenomenon of adaptation is the level of the replicator - the gene.

We need a name for the new replicator, a noun that conveys the idea of a unit of cultural transmission, or a unit of imitation. 'Mimeme' comes from a suitable Greek root, but I want a monosyllable that sounds a bit like 'gene'. I hope my classicist friends will forgive me if I abbreviate mimeme to meme. If it is any consolation, it could alternatively be thought of as being related to 'memory', or to the French word même. It should be pronounced to rhyme with 'cream'.

For more than three thousand million years, DNA has been the only replicator worth talking about in the world. But it does not necessarily hold these monopoly rights for all time. Whenever conditions arise in which a new kind of replicator can make copies of itself, the new replicators will tend to take over, and start a new kind of evolution of their own.

A replicator may be said to 'benefit' from anything that increases the number of its descendant ('germ-line') copies.

Replicator selection is the process by which some replicators survive at the expense of other replicators. Vehicle selection is the process by which some vehicles are more successful than other vehicles in ensuring the survival of their replicators

The controversy about gene selection versus individual (or group) selection is a controversy about whether, when we talk about a unit of selection, we ought to mean a vehicle at all, or a replicator.

I define a replicator as anything in the universe of which copies are made.

An active replicator is any replicator whose nature has some influence over its probability of being copied. For example a DNA molecule, via protein synthesis, exerts phenotypic effects which influence whether it is copied: this is what natural selection is all about.

A passive replicator is a replicator whose nature has no influence over its probability of being copied.

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.

A dead-end replicator (which also may be active or passive) is a replicator which may be copied a finite number of times, giving rise to a short chain of descendants, but which is definitely not the potential ancestor of an indefinitely long line of descendants.

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.

But whether it succeeds in practice or not, any germ-line replicator is potentially immortal. It 'aspires' to immortality but in practice is in danger of failing.

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.

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

The word replicator is purposely defined in a general way, so that it does not even have to refer to DNA.

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.

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

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).

An arbitrarily defined length of chromosome, or potential replicator, may be said to have an expected half-life, measured in generations.

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.

To regard an organism as a replicator, even an asexual organism like a female stick insect, is tantamount to a violation of the 'central dogma' of the non-inheritance of acquired characteristics.