Analogy between flowers and sexual swellings in monkeys

(writing in progress)

Baboons and other monkeys have extremely developed sexual swellings in the females around oestrus (https://seriousmonkeybusiness.files.wordpress.com/2011/08/800px-baboon_in_estrus.jpg).

The main function of these swellings is to inform the males that the individual female is ready to copulate. However, there seems to be ‘overkill’ here, because the swellings are extreme to the point of absurdity. For an idea of what I mean here, visualise a nubile young woman going shopping in her local area with a full-length neon orange suit, a 1-m tall orange hat, and a banner reading in foot-high letters ‘I’m hot, I love boys of all sizes, my phone number is SEX069069’.
 
According to http://pin.primate.wisc.edu/factsheets/entry/olive_baboon/behav, just the oestrus swelling alone can, in adult females, boost the body mass by up to 14%.

Way over the top, by any standards, not so?
 
It has just struck me for the first time that there may be a valid analogy here with colourful flowers in the plant world.
 
Now that I think of it, conspicuous flowers present a similar puzzle in at least certain plants. There are many ways to disperse and receive pollen. If animals are to be used as vectors, there are many subtle ways to attract them. Plants, particularly those growing in dense stands, hardly need to advertise themselves with such gaudiness, do they?
 
I suspect that the plants in question are doing more than simply ensuring that they get pollinated. What they are additionally trying to ensure is that many different individuals of the same species provide pollen to choose from. By ‘overstimulating’ the insects, for example, relative to the basic need of just a few visiting insects and just a few deposited grains of pollen, these plants ensure that the ovule has many ‘suitors’ to choose from when it comes to accepting the pollen grain that is to fertilise the ovule.

Just as sex in itself is somewhat ‘over the top’, considering that plants could theoretically reproduce vegetatively (e.g. by budding or suckering or various other methods of cloning), so the sheer size and gaudiness of some flowers seems ‘over the top’ in attracting a virtual frenzy of activity by pollinating animals.

Flowers seem in many cases to have evolved along the lines of extravagance rather than economy, raising the question: ‘if efficiency is at a premium, in which ways is it more efficient to have so many different pollen grains to choose from?’
 
The puzzle is compounded by the likelihood that such gaudiness can only increase plants’ attractiveness to their enemies, such as seed-killing insects. There is a price to be paid for self-advertisement, so the self-advertisement had better be worth it.
 
So, I could argue the following:
In one sense, gaudy flowers (particularly of plants that grow in dense stands as opposed to being scattered inconspicuously among other, larger and commoner, plants), achieve an agenda combining maximum choice of paternity with maximum testing of ‘immunity’ in the broadest sense.

Instead of doing what would seem to be the sensible thing, namely to keep a low profile and raise the sexual standard just high enough above the herbaceous horizon to attract the essential minimum of one pollinator, what really happens is exuberance on both counts: combining what amounts to an orgy with what amounts to a reproductive gauntlet.
 
So, do sexual swellings in baboons and other monkeys represent a combination of what amounts to an orgy with what amounts to a reproductive gauntlet?
 
Is the similarity between flowers and the sexual swellings of e.g. baboons not apparent, in their colour, their extent and complexity, and their delicateness and physical vulnerability? These are, to me, among the most ‘floral’ anatomical structures in the mammalian world. To human eyes they are far too ugly (indeed, quasi-obscene) to conjure up the image of flowers if one approaches the problem from an aesthetic viewpoint. However, if one approaches the problem from a functional viewpoint, is the analogy not evident? 
 
Humans tend to be so biased by our aesthetic sense that we appreciate showy flowers with little sense of their absurdity. However, if one ponder the costs of these structures even from just the point of view of evaporative losses, one may see that plants must surely have good reasons to configure flowers in the ways that they do.

Flowers are surely inconvenient in various ways inconvenient for plants to produce. We know of many plants – epitomised by grasses – that manage pollination using no showy structures, and the simple mechanism of wind.
 
What this all adds up to:

Most authors would not call sexual swellings in monkeys 'sex organs' outright. They might prefer to call them secondary sexual features or sexually related organs. However, how can the parts of the body subject to sexual swelling in monkeys not be described as sex organs?

I suggest that we can – at least from one perspective – view the sexual swellings of monkeys as the closest thing, among mammals, to floral organs. All flowers without exception are sex organs, and the sexual swellings of monkeys are, likewise, sex organs although I cannot recall them having been described with such candour in the literature.

(writing in progress)

Publicado el jueves, 30 de junio de 2022 a las 04:35 AM por milewski milewski

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The following shows the normal dark grey tone of the paracallosal bare patch in anoestrus females of the anubis baboon.
Papio anubis adult female and infant: http://image1.masterfile.com/getImage/841-07457424em-Olive-baboon-(Papio-cynocephalus-anubis)-infant-riding-on-its-mother's-back,-Serengeti-National-Park,.jpg 

The paracallosal patch turns pinkish in oestrus and in pregnancy. However, the pinkish is centred on different anatomical structures in the two cases. The paracallosal patches are not a focus for the oestrus display. Note that the ischial callosities are pale but not pink.

Papio anubis possibly pregnant female:
http://l7.alamy.com/zooms/07a6eb987d9742ff80ba01a766febf58/yellow-baboon-savannah-baboon-anubius-baboon-olive-baboon-papio-anubis-ebtbd8.jpg

The following shows the relative positions of anus and vaginal opening rather clearly in the oestrus swelling. Note that when faeces fall from the anus they would tend to soil the vaginal opening because of the angles set by this swelling and because, for all this extreme distortion, the distance between anus and vaginal opening remains minor. Also note the paleness of the upper eyelids of this female, which is blinking.
 
Papio anubis adult male (left) and adult female with oestrus swelling (right):
http://l7.alamy.com/zooms/5256c1b498de46d2a3089a5e1a20b242/male-olive-baboon-grooms-female-who-shows-swollen-callosities-lake-a41gag.jpg

Anotado por milewski hace más de un año

The following photo of Papio ursinus (adult female with nearly maximum oestrus swelling: https://seriousmonkeybusiness.files.wordpress.com/2011/08/800px-baboon_in_estrus.jpg) shows particularly clearly the oestrus swelling in the chacma baboon.
 
Note that the pink oedematous tissue seems to be centred on both the anus and the vulva, spreading laterally at the base of the tail, and ventrally down the perineum towards the crotch (where less vivid in its pinkish hue).
 
Note the gloss of this tightly turgid tissue (the liquid being mainly extra- rather than intracellular). Note the complexity of the surface, which tends to retain faecal matter close to the vagina, something that seems counterintuitive.
 
The ischial callosity remains visible (dull flesh-coloured), with a clear boundary between it and the oestrus swelling. However, there is encroachment by the swelling on to the callosity, and it is now impossible to sit on the callosity in the normal way.
 
Note how inconspicuous the bare patch of dark skin is, lateral to the ischial callosity.
 
I find it odd that cercopithecids have evolved a structure as specialised as the ischial callosity, but then rendered it useless during oestrus.
 
Note how ‘hidden’ the gaze of the chacma baboon is even in this illumination, in which there is no shade cast on the eyes by the superciliary ridges of the skull. This partly because there is no display of the eye-whites.
 
Another new thought: when the male mounts a female with full oestrus swelling, he places much of his weight on his hands, gripping her rump/haunch. But where exactly does he place his hands and how can he avoid hurting her by pressing down on this sensitive pink swollen tissue. Is it not odd that the swelling spreads so far forward (laterally) from the anal region, given that this is where the male must put his hands to bear much of his weight during copulatory mounting?

Anotado por milewski hace más de un año

The following is illustrative of baboons: Papio cynocephalus mature male and sexually mature female http://cache2.asset-cache.net/gc/526439941-copulating-baboons-in-amboseli-national-park-gettyimages.jpg?v=1&c=IWSAsset&k=2&d=f8FZzNtSoncSws64vUpm5WfqJR7TUQN0Y1GAbVQoCAfFZhozp1yBI7fKBPq2mCoeNS%2FNdI7yR5OxueQZWtmBzQ%3D%3D. It shows the yellow baboon in Amboseli National Park in Kenya.
 
This photo shows the following points.
 
There is great sexual dimorphism in body size and muzzle size without much dimorphism in colouration. The male is at least double the body mass of the female in this case. The pale cheeks of the yellow baboon are clearly evident in this male individual. The yellow baboon lacks a noticeable cape in the male and this individual shows the greatest development of the cape in this species. The yellow baboon is more like the chacma than like other species of baboons in that the forehead and muzzle lie at different angles.
 
Note how the male places his whole weight on the female during copulation, including using the big toes to ‘climb’ on to her calves. This is one of the few times that baboons use the big toe ‘opposably’ for any purpose other than climbing trees. As far as I know, all male baboons ‘climb’ on to the calves of females in this way, when copulating.
 
I am not sure that enough has been made of the fact that baboons are ‘climbing copulators’ and that the female, although half the mass of the male, takes his whole weight on her hindquarters (partly via the hands placed on her haunches). This experience of great weight on the hindquarters presumably causes the female to be far from passive during copulation, because she has to tense the muscles of her hind legs greatly to bear this weight without collapsing. This is presumably a large part of the sexual stimulation for her during copulation, and may be linked to the fact that consummating copulation in baboons requires not one mounting but several in succession, after which the male ejaculates.
 
So, there are at least three peculiarities of copulation in baboons and other supersocial cercopithecids, that may not be fully appreciated by monkey-watchers: the orientation of the vagina is affected by both the oestrus swellings and the bearing of great weight by the hips, copulation can only be consummated after several mountings and dismountings, and the female must allow the male to climb on to her completely, so that all parts of his body leave the ground.
 
It is interesting that in baboons the female attracts attention to the act of copulation by means of special copulatory vocalisations, but the male does not use the tail for any ‘body language’ during this act.

The dark bare patch on the rump, lateral to the ischial callosity, is clearly visible in this male individual, and would not be so obvious if this were the chacma baboon.

The tail, as in anubis and chacma baboons, has a distinct kink about one-third of the way from the base, and has no sign of a tassel. In hamadryas and guinea baboons the tail is quite different, being shorter, lacking the kink, and possessing a tassel of sorts.

Anotado por milewski hace más de un año

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