It is dangerous (from a logical reasoning point of view) to assume that Evolution occurs with a PURPOSE. It is not a requirement in evolutionary theory, that every observed feature of a creature or it’s culture be NECESSARY for that creature to come into existence or survive, but it is a common error that people make when postulating about “reasons” for what is.
Also, I want to add my support to recognizing that we do not yet know even the majority of what each element of our DNA do, in their entirety. Therefore it is too soon to try to make an argument based on the fact that we HAVE NOT found specific genes or other parts of DNA which control sexual orientation.
We are not the first people to have this debate. Your view is, I believe, more common in the USA where Gould’s writing has had a greater influence on evolutionary thinking.
Biologists such as Jon Maynard Smith, Richard Dawkins, George C williams, Colin Pittendrich and W D Hamilton, would tend towards viewing the gene as the fundamental unit of selection, so if my language/concepts really are backward, at least I am not alone in that regard.
“the natural selection of phenotypes cannot in itself produce cumulative change, because phenotypes are extremely temporary manifestations.”-George C Williams.
"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…
…It is its potential immortality that makes a gene a good candidate as the
basic unit of natural selection." Richard Dawkins, The Selfish Gene.
Selective pressures–that is, those that determine the likelihood that an organism will survive to maturity and procreate–act at the level of the organism as a whole. A gene carrier might have a gene or combination of genes that express a capability for superior fitness, but if the organism and the population from which do not display overall fitness and adaptability, the gene will not prevail regardless. An analogy for consideration is automotive technology; better performance or safety technology may make for a better driving experience, but what determines safe and efficient driving behavior is the driver, not the technology. A good driver can be pretty safe in a '62 VW Beetle despite its deficiencies; a careless driver may be accident prone regardless of the safety and performance features of a modern luxury automobile.
The conceit of gene-centric theory–that genes are “responsible” for their own propagation–is that it tries to reduce the complex interplay of influences upon the organism, including lateral gene transfer, to this simple mechanism of ensuring the broadest propagation of the gene. It has utility for rationalizing certain behaviors that otherwise seem contrary to fitness but it often leads to a bunch of spurious rationalizing, as evidenced here with this hypothetical “Gay Uncle” gene; it sort of makes sense that some people might carry a gay gene giving them the time and energy to help raise their siblings’ offspring to propagate their gene until you start looking more deeply into the complexity of sexuality, e.g. the fact that sexual identity is not binary, there are plenty of homosexuals who have fathered or birthed children, we have social structures which provide for communities supporting child rearing that often do not welcome homosexuals, et cetera. In fact, for social behavior in anything more complex than an insect or arthropod, trying to apply genetics as the primary mechanism behind behavior is a fool’s errand. We know that genes play a part in behavior because people will often behave in ways contrary to their training and societal expectations (e.g. homosexual attraction in 20th Century Western culture) to a point of being placed in physical danger, but the idea that a gene can direct an organism to behave or respond in ways specifically to propagate itself within the context of competing influences of tens of thousands of genes is not a sensible argument.
I don’t disagree with much of that beyond the opening sentence or two. Remember, I was arguing that the “gay uncle” hypothesis made no sense. It is certainly not a consequence of a genes-eye-view of evolution. Quite the reverse. I think what you are arguing against is some sort of strong genetic determinism, which I, like Dawkins and just about everyone else I’ve ever heard from would also reject.
What I am saying is that it is the genes which “live or die” based on their phenotypic consequences. The bodies themselves, along with any beneficial traits they posses are always destroyed.
Of course, epigenetics, extended phenotypes, lateral gene transfer, etc all complicate things, but they don’t alter the underlying fact that there are no differential survival rates among organisms. The survival rate for all organisms is zero (bacteria/archea could arguably be described as immortal, but that’s not relevant to this discussion).
It is the view expressed by people like Gould (which you came close to hinting at yourself) that I can’t make sense of. That the genome is somehow a passive record of the evolution of bodies, rather than the thing which is actually evolving.
That makes them the unit of replication. Selection takes place on things like traits, etc. Maybe we’ve just got a terminology issue here though.
Agreed - it doesn’t have to be perfect - only ‘good enough’. In fact, it’s unlikely to be perfect, because there’s no actual plan - it’s just a big pile of trial and error. Exerting the exact necessary selective pressure for metal bones (assuming such a very specific selection force could be designed) is still not guaranteed to ever actually produce metal bones.
Again, agreed - maybe a population in which only 85% (or whatever) of individuals are reproductive is situationally optimal (or at least as situationally non-suboptimal as the process can derive)
Very likely, I think. Joe public wants to hear “This is the gene for blue eyes, and this is the gene for pretty toes, etc” - some cases might be like that; many others are likely to be parts of a networked system with lots of interdependent parts - a bit like the way you can’t point at a single node in a trained neural net and say “that’s the node that is responsible for recognising the letter A”.
I really like Dawkins-- he’s one of my favorite authors. But I haven’t read The Selfish Gene, and if you look at the wikipedia page, he gets a lot of criticism about being sloppy in his not differentiating enough between those two concepts. Also, the book was published 40 years ago, as a popularized science book. Not the best of cites, especially when you can find other cites from that book that contradict the ones in this thread. Again, check out the wikipedia page.
The Selfish Gene is IMO, the best thing he ever wrote. I would highly recommend reading it. The fact that it is 40 years old and was deliberately written to be understood by laypeople, is not to it’s detriment. You can decide for yourself whether that criticism is accurate. Dawkins and others have, IMO, dismantled many of the objections.
The quote I think you’re referring to as an apparent contradiction, isn’t one. I alluded to something similar earlier in this thread when I said phenotypes are the means by which genes are selected. Genes survive because of the bodies they build, but the bodies themselves do not survive, do not replicate, do not vary in frequency and I don’t see any sense in which can meaningfully be said to be selected.