The Evolution of Sex

This has long been an interest of mine. It dates back to the old talk.origins days, prompted by a Creationist taunt with familiar tone – “I’d like to see someone explain the evolution of sex …” (with the implicit “hurr, hurr”). I articulated some thoughts, then was rounded on by the ‘mainstream’ community. I got a flavour of the world through Creationist eyes – an equally familiar tone: some very sharply expressed contempt and an invitation to f*** off back to high school and learn meiosis.

But, the more I thought about it, the more convinced I became that the ‘twofold cost’ picture traditionally presented, one that demanded an offsetting benefit of similar weight, was simply incorrect, however lofty the figures proposing it. The problem as expressed for a dioecious population (one with separate males and females: the ‘twofold cost of males’) or from the perspective of a locus on a genome (the ‘twofold cost of meiosis’) leads to the same result: an apparent halving of reproductive output for a female, or of survival odds for an allele. Yet since dioecy is quite rare, and ‘selfish alleles’ only exist when recombinant sex does, these cannot be taken as relevant to the origin of sex, and not all that relevant beyond it. The sensible perspective, it seems to me, is that of the haploid genome. From such a perspective, we are binary organisms – temporary unions of haploid genomes. It cannot be inherently more costly to unite then separate than simply to do nothing. The view that sex (as syngamy: gamete fusion) should have existed for only a moment before being erased by permanent diploidy seems wrong. Meiosis is the brief return of the native organism – the haploid. Permanent diploidy is cancer: a trap.

It’s more complicated than that …

I have written the above essay summarising my views. It is a bit of a dry and technical read – few pictures, even fewer jokes! This venue is not particularly conducive to a sensible discussion of the subject. It may be of interest to no-one: too amateurish for the professionals, too technical for the interested layman. Almost none of it is really original thought, being more a synthesis than anything groundbreaking. Beyond the choice of perspective, there are only a couple of ideas I have not seen elsewhere (I might remain coy about which those are!).

I’d prefer comments to be held off until the paper has been read (a big ask; it’s 50 pages!) but I hope it doesn’t descend into yet another discussion about semantics, metaphysics, the evidence for common descent, or any other of the conversations we have all had on a few dozen other threads.

My own time defending this is limited – I’m off to the Pyrenees for 5 weeks on June 24th. But, if anyone is interested …

207 thoughts on “The Evolution of Sex”

  1. MungMung

    Rumraket thinks there is but one single canonical tree from morphological features which matches up precisely with the one single canonical tree from genetics.

    Either that, or when he argues for “the twin nested hierarchy” what he really means is that given a variety of data sets some can be made to match up. Sort of.

  2. RumraketRumraket

    Mung: Rumraket thinks there is but one single canonical tree from morphological features which matches up precisely with the one single canonical tree from genetics.

    I was not aware that I believed this.

    Either that, or when he argues for “the twin nested hierarchy” what he really means is that given a variety of data sets some can be made to match up. Sort of.

    So those are the only two possiblities? Either I believe the above, or this second tailor-made-to-sound-stupid option?

    I see that you have nothing more to contribute to this discussion. I accept your concession.

  3. Alan FoxAlan Fox

    For those interested in Allan’s progress on his 500 mile hike in the Pyrenees along Haute Route from Hendaye to Banyuls, he spent last night in Gavarnie, roughly a third of the way along.

  4. MungMung

    Alan Fox: For those interested in Allan’s progress on his 500 mile hike in the Pyrenees along Haute Route from Hendaye to Banyuls…

    Can we Un Feature his OP given that he’s not responding?

  5. Alan FoxAlan Fox

    Mung,
    Yes, Allan is mostly out of signal except near population centres. The weather in the high Pyrenees is thunderstorms at the moment which will hamper communications, too. At least the EU has just abolished roaming charges.

    I’m sure he’ll return refreshed and recharged and wanting to pick up points now hanging. We can always re-stick this OP in that case.

  6. Neil Rickert

    phoodoo: You see, the point is, in evolution, we start off with this assumption that everything adapted, without a plan, to end up perfectly suited to its environment. Everything is perfectly suited to its environment at any given moment. We never seem to describe a living organism as not well suited for its environment.

    I missed this (skimmed past it) when it first appeared. I’ll comment now.

    Most evolutionists will admit that suboptimal can be good enough. So the charge that perfect adaptation is assumed seems to be off.

    From my perspective, an organism is always adapted to its environment. It may be suboptimally adapted, but that can be good enough. As long as the population can stay roughly stable, that’s good enough. If the population is in decline, that’s the pathway to extinction. If the population is expanding too rapidly, that cannot continue without destroying the environment.

    According to the Darwinian picture, the explanation of biodiversity is to be found in natural selection optimally adapting a population to its environment. But if that worked, it would lead to exponential growth and destruction.

    I prefer to look at it the other way. Natural selection isn’t the solution; it’s the problem. Natural selection leads to extinction.

    If the population is to survive, it needs to stay sufficiently well adapted to have a reasonably stable population. Darwinists tend to think of a fixed environment and varying organisms, with natural selection as fitting the population to the environment.

    But environments can change too. Instead of fitting the population to the environment, there’s the possibility of fitting the environment to the population. That’s roughly what farmers and horticulturalists do.

    So why not a combination of both? That’s how I see evolution. I see a population experimenting with change, and using that change to explore its ability to expand into other niches. And I see the environment changing for reasons beyond the control of the population. So the population is exploring change, and that gives it the possibility that it can track environmental change. And, of course, sexual reproduction is an important part of what allows the population to explore change.

  7. Alan FoxAlan Fox

    I see folks are breathless for news of Allan Miller and his marathon march of five hundred miles across the Pyrenees from the Atlantic at Hendaye to the Mediterranean at Banyuls-sur-Mer.

    I can report that Allan is on schedule to arrive in Banyuls tomorrow and then should be back communicado within a couple of days.

Leave a Reply