Females with penises? Biology gets much weirder than that. Read More
Excellent read. I'd only add that Conley didn't ask subjects if they would have sex with Johnny Depp. They asked subjects to rate the likelihood of agreeing to a sexual encounter. This was presumably to soften the hard "yes/no" question into something more vague and protective.
Fair point. They asked for an "assessment". In fact what they did was confirm Clark & Hatfield.
If they just added an erratum slip that read "For "refute" read "confirm" throughout." then the piece would read just fine....
Great piece Rob.
I'm just confused that again you say: "females created males?" It sounds as if you are saying that females came first when clearly from your explanation of the divergence of the size of sex cells (and therefore the origin of male and female), the two strategies must have co-evolved.
But the way you talk about Bdelliod rotifers sounds as if you think that what they do now is what organisms did before there were eggs and sperm, which is not correct. They are a species that has lost males they once had. To go back to their ancestors that did not have males (i.e. any sperm production, and before the 'recent' loss of their males) is to go back to an ancestor we all share, and to the origins of sex which you describe, and where the two sex cell types co-evolve - each sex creating the other.
I don't normally reply to faceless folk-but given that we are discussing cloning, why the hell not?
Bdelloid rotifers clone themselves. They used to have sex and now don't--having given it up roughly 80 mya.
Animals have two types of sex cells, big and little. If they are hermaphrodites they have both. Isogaqmous creatures differentiate sex in different ways (e.g chemicals) and some can have hundreds of sexes (slime molds, for example).
Bdelloid rotifers are the only Eukaryotes--that I know of--that don't use sexual reproduction. They used to--they abolished males. They are asexual females. Maybe its a tad fanciful to call all the asexual reproduction out there (yeast, strawberries, sea anenomes etc) female--but they sure as hell aren't male. Maleness is something species create and use sometimes, but not always. This is not an option with femaleness.
I'm not saying anything about "degenerate y chromosomes" or anything similar--simply that male is an option.
Now over time lots of apparently asexual critters have been shown to be simply hiding tiny males around somewhere-- Tramini aphids, Oribatid mites and so on. However bdelloid rotifers seem to be genuine immaculate conceivers--they clone and therefore there has been no genetic novelty formed by meiosis for a long time.
Judson, O. P., & Normark, B. B. (1996). Ancient asexual scandals. Trends in Ecology & Evolution, 11(2), 41-46.
Goes into details.
Anyway--females are primary. Several species will go from reproducing using them to not and then back again depending on ecological factors. Is it stretching it a bit to say that females therefore create males? Well, maybe--but I'm not going to lose a whole lot of sleep over it.
So it is your own definition of female :) not a biological one.
I grant that it is complicated but if we start with two haploid cells merging for a while then parting, there is no male nor female. Just two single-celled organisms.
Then if the haploid cells stay together as a diploid and divide as diploids and those cells stick together we have a multi-celled organism.
If some of the cells divide to form haploid cells that leave that body we have sex cells. If these cells from all similar organisms are a similar size, male and female sex cells have not yet evolved. When selection leads to different size sex cells then we have female and male - as you yourself described as the origins of the two sexes.
The Parker/Baker/Smith model suggested the smaller cells evolved first (advantage of numbers)and then there was selection for larger cells - they even argued that the small cell was like a parasite on the larger cell. Maybe, maybe not. John Maynard Smith also agreed with this and wrote that the male came first.
Whatever, the road to becoming smaller and the road to becoming larger were inter-dependent.
We don't get parthenogenesis, like in the Bdelloid rotifer, until after there has been two sexes. The original multi-celled organisms did not produce diploid cells that then would create an adult though they likely split bits of themselves off.
The original multi-celled organisms would start by releasing similar though varying size cells, then selection follows for the two sizes, as you say, and this is the origin of 'female' and 'male' (and most likely from the same body. Hermaphrodites. Think sponges and hydra and coral. Only later would some of these bodies specialize in producing one type of cell or the other.)
Using your own description of the origin of the sexes, if the large egg, i.e. the female, came first this is a haploid cell. Why reduce your number of sex cells by investing more and more to make that cell bigger? What is it going to fuse with? Where is the advantage? (It may be the mitochondria getting the advantage by out-numbering that in the other cell) If it did happen then selection would quickly lead to selection for cells with minimal investment - sperm. The two are inter-dependent. And we are still at the stage of the simplest of conglomeration of cells, perhaps volvox-like. Something that produces both types of sex cell. No cell specialization. Probably.
I'm sure you think I am laboring this point but if this is about biology and the origins of the sexes, and the female is defined by the production of large haploid sex cells that have to fuse with another haploid sex cell, and you are arguing that this went on before there was any production of small sex cells (males) then it needs to be explained how that happened. It is logically inconsistent to describe the origin of sex cells as the origin of the sexes and to argue that females came first - the two cannot both be correct.
I am really not trying to be antagonistic here. I spent a lot of time on this subject in the past and unless there is something I've missed, something you know that I don't :), then I simply cannot get my head around the idea that females came first when females didn't - couldn't - exist before anisogamy. And you say this yourself.
It is strange to see you argue that they did exist before anisogamy at the same time as arguing that anisogamy is where female and male started. Can you understand my confusion?
And telling others that females came first and created males could lead to all kinds of mistaken beliefs.
Nothing I have said is particularly controversial--although the spin I put on it might annoy some folk. Female is large sex cells. It is not just me who thinks of clonal reproducers as female--thats pretty standard. Granted, I could make a sharper distinction between
1) Females arrived first (not true)
2) Females are in some ways more basic (basic body plan is female, ontongeny does to some extent recreate phylogeny)
3) Females are involved in an ongoing process of creating males because female choice mechanisms are the key driver in primate evolution.
So--fair enough--anisogamy is co-evolution and I guess I could be more direct about saying that. However I stand by the point that females create males (for the reasons above). And, while males also create females there is no scenario in which females could be discarded. The reverse is not true
Clonal reproducers are female, I agree, but female clonal reproducers did not exist before the two sexes evolved, they only came later. Glad to have agreement on that.
I'll leave 2) and 3) because, as I'm sure you know, evolution is rather more complicated and debate about it can be long and arduous, and not necessarily that interesting to others :)
My main concern is about avoiding the inadvertent spreading of a new creation myth where 'Eve' rather than 'Adam' came first - even if she can still be blamed for everything lol
Nope--I never agree to disagree. Disagreeing is waayy more fun. In this case--a useful corrective to the biolgically and psychologically very common idea that males are the basic sex and femles deviate from that is required.
We keep missing stuff by forgetting it.
So you are saying it is not more complicated?
What about birds where it takes estrogens to suppress male traits? I'm sure there is a lot more to still be learned about this, but this signals "it is complicated" to me.
Or reptiles? In some species it is eggs developing in warmer temperatures that become female and in others it is eggs developing in cooler temperatures. What does "the basic body plan is female" even mean in these species?
And what about bees where the male develops from an unfertilized, haploid egg cell? Again, how can we even start with a statement that the basic body plan is female?
Of course it is ridiculous to think that males are somehow the norm and females a deviation from that norm. I don't see how simply reversing that statement takes us any closer to describing reality.
The original multi-celled organisms most likely produced both eggs and sperm. In that sense the basic body plan is hermaphrodite (we probably get to some fish-like vertebrate, in the animal kingdom, before we get to separate sexes). Being subsequently successful as a body that only has ovaries depends on the existence of testes in other bodies. Ovaries that either go through meiosis and then fuse two haploids, or just through a mitotic division to produce a diploid cell that can develop into an adult, came later, and are rare and usually not successful long-term. This is certainly not evidence for such bodies being the basic body plan.
"Female choice" is, of course, a big subject in evolution. But that somewhat glib term hides a multitude of meanings, and produces a multitude if misunderstandings. In all evolution it is offspring survival that, in retrospect, 'decides' who the ancestors are, and the traits that are perpetuated, and therefore the 'right choices'. The 'choice' can often be at the level of the sex cells, where some molecular message is read about the relatedness of the male sex cell, for example. Even plants makes these 'choices' about which pollen cells to use.
I never agree to disagree either.
And I don't know what you mean by "missing stuff by forgetting it".
The main problem to me seems to be not knowing stuff in the first place, closely followed by thinking we have found a simple answer. What was it that Mencken guy said? "For every complex problem there is an answer that is clear, simple, and wrong."
All your examples, hymenoptera, reptile etc, make my point for me. Perhaps you should go back a re-read what I actually wrote. I think you are arguing against some notional (perhaps previous) interlocutors as I have no idea what you think you are disagreeing with any more.
If you want to write a blog where you just go "it's complicated" over and over--be my guest. Send me the link when you are done. However--I would suggest that Olivia Judson has done a much better job of this already--try her blog and excellent book (and TV series).
I think we are done here
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