On the evolution of the sexes

[Jon]

Does anyone know of any decent reading material on this subject, or indeed have any insight into it. What do we know of how the sexes came about, or why evolution led to sexual reproduction between individuals of a species, etc. It's just an argument I often encounter with people putting forward as if it's a show stopper and a real problem for proponents of the theory of evolution that the sexes exist and that it's some kind of logical fallacy because they would have had to have developer simultaneously, for example. I'd like to educate myself a little further on the subject, wondered how other people understand the topic.

[Surlethe]

Well, a little bit of research shows that sexual reproduction is so old, it predates both the plant and animal kingdoms. These people probably treat sex like it's a show-stopper because they can't imagine sexual reproduction happening in any way than with two sexes with distinct sexual organs coming together and mating -- i.e., the way it happens in mammals. In reality, there are hermaphroditic animals (snails, e.g.), plants with sex organs (flowers are a good example of this), plants that reproduce both sexually and asexually, and pretty much every conceivable variation on the theme of two sexes.

At the end of the day, it's easy to see that recombining genes is quite beneficial, and it's not difficult to see how the wide spectrum of sexual reproduction techniques could have evolved from primitive ancestors who swapped genes.

[Darth Wong]

As said above, there are certain plants and animals today which can reproduce either sexually or asexually, so it's certainly not a show-stopper: we have living examples of the "missing link".

As for the reasons for its development, the short version is that it has to do with increasing the range of genetic diversity possible within a species.

[Junghalli]

Indeed, even many bacteria can exchange DNA via plasmids. It's one of the things that makes resistant diseases so potentially nasty.

[Turin]

I'm reading an awesome book on the subject right now called The Red Queen: Sex and the Evolution of Human Nature. The first few sections cover the concepts of "why is there sex at all?" and "why are there (usually) two sexes?" It's a good book if you're generally familiar with evolutionary theory but want some more in-depth look at the process of sexual selection (as opposed to natural selection). Matt Ridley, the author, posits that a lot of the questions surrounding the nature of sex and the human nature as it relates to sex are subject to the Red Queen effect.

[Lord of the Abyss]

I'm reading an awesome book on the subject right now called The Red Queen: Sex and the Evolution of Human Nature. The first few sections cover the concepts of "why is there sex at all?" and "why are there (usually) two sexes?" It's a good book if you're generally familiar with evolutionary theory but want some more in-depth look at the process of sexual selection (as opposed to natural selection). Matt Ridley, the author, posits that a lot of the questions surrounding the nature of sex and the human nature as it relates to sex are subject to the Red Queen effect.

I second this recommendation; I thought of it immediately upon reading the thread title.

[Companion Cube]

I recall there's a hypothesis by someone called (uh...) Kondroshov, who put forward that sex was a useful way of concentrating (and gradually eliminating) deleterious mutations. In an asexual population, any non-lethal deleterious mutations that arose might simply remain in a particular line of descendants, reducing their fitness.

Sex, on the other hand, would allow these unfit individuals to breed with other lines, and either mitigate the effect of their damaged genes or perhaps result in an individual with enough deleterious mutations to actually have a lethal effect and prevent that one from spreading its genes. So the overall effect would have been to remove two inferior genes from the pool; a population of asexual organisms would, on the other hand, accumulate various hereditary mutations and gradually decrease in fitness.

[The Yosemite Bear]

is it bad that I'm now thinking about how much I like using flower sex organs as a spice?