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In the third chapter of The Selfish Gene: Immortal coils, Dr.Dawkins makes the following statement while arguing for the case that ultimately "the gene" as he defines it is the unit of natural selection.

Natural selection in its most general form means the differential survival of entities. Some entities live and others die but, in order for this selective death to have any impact on the world, an additional condition must be met. Each entity must exist in the form of lots of copies, and at least some of the entities must be potentially capable of surviving—in the form of copies—for a significant period of evolutionary time. Small genetic units have these properties: individuals, groups, and species do not.

I am not sure what "impact on the world" he is talking about. Could someone explain this? He then goes on to say..

An individual body seems discrete enough while it lasts, but alas, how long is that? Each individual is unique. You cannot get evolution by selecting between entities when there is only one copy of each entity!

Whereas in his other book, The Blind Watchmaker, he describes a computer drawing program EVOLUTION where he does precisely that, i.e, select between entities (here, computer drawn insect-like figures) of which there is only one copy and allows them to evolve. This seems contradictory to his above statement in The Selfish Gene. Could somebody explain?

tl,dr: Why must there be many copies of entities that are being selected for evolution to be possible?

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"Impact on the world" is just his writing style. Dawkins means "evolutionary significance". For example, all the intermediate forms leading up to the modern horse have been evolutionarily significant because they contributed to survival of the lines of descent that are still present. Any tiny evolutionary branch that dies out would have little significance or impact.

In the first part of your second question, the answer is again Dawkins' writing style plus the fact that he's writing for popular consumption. And, his own thoughts have a way of evolving just as they should; so we shouldn't expect perfect consistency between what is said between sequentially written books. The Blind Watchmaker was written to convince people that evolution can produce complex organisms without any pre-existing goal to do so, using a relatively simple process. The Selfish Gene was written to promote his idea that the unit of evolution is the gene. (Note that his idea is not necessarily correct.)

In the second part of your second question you ask:Why must there be many copies of entities that are being selected for evolution to be possible?. The answer to this is that it is NOT necessary. It's simply a much more easily implemented - and generally better- evolutionary strategy. If there is only one organism, and selection means killing it if it is unable to adapt to a given environmental change, then failure to adapt puts an end to it and all its possibilities. If, on the other hand, that one organism produces a series of single copies (offspring) and each of them has some random genetic variation that's subjected to selection, there's a chance that some will make it past the selection process. That's equivalent to the one organism producing a lot of offspring at the same time, each with its own genetic differences.

This is a slightly SiFi perspective on the above, but: In general, it's a lot safer to test a disposable copy of oneself against a new danger, than to test oneself directly. If the copy passes the test, it's safe to face the danger directly. If the copy fails, then you can test a slightly modified version of yourself against the danger. If that modified copy passes, then if you're able to do so, you could make the same modifications to yourself and go face the danger. However, there are now two identical new modified copies of you. One of you is superfluous, so you flip a coin to decide which survives.

In the SiFi scenario, we have one organism evolving safely up one possible branch of an evolutionary tree. But if that organism reaches a dead end from which there is no escape, its branch dies. On the other hand if all the other branches are allowed to continue (that is, if you let both copies survive and evolve independently), there's a far better chance at least one branch will still be growing and branching far in the future.

I personally think Dawkins "Selfish Gene" idea fails when we try to fit it into that picture.

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  • $\begingroup$ Your hypothetical falls apart for several reasons, not the least of which is copies take resources to make as much as the original took to make, and a copy is not superfluous, otherwise asexual reproduction would not exist, it is no safer to test on your copy as yourself, unless your copy is not a copy, which does occur , see skin cells. You are needlessly anthropomorphizing selection in your example. $\endgroup$ – John Apr 30 at 3:54
  • $\begingroup$ It is pretty difficult to say anything about evolution in layman's language without being accused either of anthropomorphizing or of invoking a diety. Please clarify "it is no safer to test on your copy as yourself, unless your copy is not a copy". $\endgroup$ – S. McGrew Apr 30 at 12:34
  • $\begingroup$ First that whole section is irrelevant to the the questions, but to answer you if the "copy" and the original are identical it doesn't matter which one is sacrificed, the loss is the same. $\endgroup$ – John Apr 30 at 12:41
  • $\begingroup$ if they are not identical what you can "test" is pretty limited, the more capable the copy the closer it is to an identical copy and the more impactful the loss of time and material, and we already see such behavior, it is essentially r strategy, make lots of low cost copies and spam the environment. similar is multicellular life where only a few cells get to reproduce the rest only being beneficial in their ability to facilitate that. . $\endgroup$ – John Apr 30 at 12:46
  • $\begingroup$ What you're saying is correct, but a bit beyond the scope of the question. IMHO, only the OP knows if an answer fits the intent of the question. $\endgroup$ – S. McGrew Apr 30 at 17:43
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"impact on the world" is referring to the cumulative effects of natural selection, the progressive alteration of a lineage. If every "unit of selection" was completely unique there would be no cumulative effect of selection, individuals would die and it would have no effect on the next generation. Bodies are unique but genes are not, a body is produced by genes that are mostly conserved from generation to generation. He is drawing attention to the fact there must be something heritable that is conserved from generation to generation for section to have a lasting effect. That heritable thing is what is being acted on, for life one earth that thing is our genes.

The computer program further illustrates his point, the "genes" (code) are carried from generation to generation mostly intact, even though each body is created new and unique from those genes, just like many organisms. that is why they can evolve just like lineages of biological life.

there is a weird dichotomy in how evolution functions, it is a step removed process. The genes are the things being altered by a process that can only interact with them through their products, bodies, but it is the genes that get altered it is the genes that are evolving.

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