A stream of thinking about the spotted hyena

(writing in progress) 
 
One of the peculiarities of the spotted hyena (Crocuta crocuta) is that, even though there is communal denning, there is no communal care of offspring.
 
Up to 10 females den in a single area, so that any adult remaining in the vicinity serves (at least inadvertently) to protect all the juveniles (which are hidden down narrow holes most of the time), including unrelated juveniles.
 
It is easy to envisage that, in such a situation, several daughters of a given mature female may have juveniles in the same denning area as their mother and their female siblings.
 
However, if a given juvenile is starving owing to delay or mishap experienced by her mother on a foraging expedition, it seems that the adult kin of the mother, despite being related to her, will make no attempt to save her offspring with their own milk.
 
It is hard to see why the society of the spotted hyena would work this way, because juveniles do inherit rank from their mother and so they might be expected to reciprocate by allosuckling, in the way seen in the brown hyena, lion, jackals, hunting dog and social mongooses. Bonds between mothers and daughters persist, as female offspring persist remain in the clan, whereas males emigrate in adolescence.
 
Whatever the reason for this meanness, the reality is that it is up to the mother to come back with a full udder, in time to save her own offspring.

Given the premium on this mother succeeding in any given foraging expedition (which can last up to 5 days days in the Serengeti, where the females range far afield (> 30 km each way and possibly up to 80 km each way) to where the wildebeest migration happens to be at that time), one can understand that it would be harmful to the interests of the species if the mother failed simply because she was elbowed aside at a kill by males.

The strategy adopted instead is to ensure that at least some females (those superior to both all the males and some or most of the females) will have unquestioned priority at food, making viable the policy of relying on milk.
 
Another interesting fact about the social life of the spotted hyena:
 
A clan may contain many members, as in Ngorongoro Caldera where food is particularly plentiful. But there is no occasion in the life of the animal when it all members of a given clan assemble for the sake of assembly. The only time when one can see most (seldom all) of the clan members together is at a kill big enough to promise food for most, even after the dominant individuals eat their fill. Up to 65 individuals have been seen together on such occasions.

But my point is that this congregation is motivated purely by competition among individuals, not by any sense of community. So one can say that the clan members NEVER assemble in any kind of solidarity, and seldom assemble at all. I do not think this is fully realised by most people with a smattering of knowledge about the species. The clan is a conceptual construct in the mind of the animals, formed indirectly by pairwise interactions (mainly the greeting ceremony).

This may help to explain my point about ‘humiliation’ not being emotional but merely a function of esteem within an extended group. No individual ever sees its clan members assembled together and sorted according to rank, as one might imagine in a human military parade. Instead, everything from the integrity of the whole clan down to the relationship between any two members is based on the information gathered in greeting ceremonies between one individual and one other individual. The rest is constructed in the mind of the hyena.

This amounts in a way to a ‘virtual clan’, not so?

In this light do you see that it may be an efficient system for the greeting ceremony to serve as a repeated opportunity for each individual to locate itself in a virtual hierarchy which it can never see as anything more concrete. This is why I find the term ‘submission’ hopeless inadequate to describe what the inferior individual does in the greeting ceremony.

The greeting ceremony does not involve ‘submission’ for another reason too: it is the inferior, not the superior, individual that initiates the greeting, voluntarily coming forward to be examined in detail and presumably to divulge all it has experienced socially since the last meeting of the two individuals in question.
 
Three other facts worth considering:
 
When the spotted hyena deposits paste from its anal gland on to grass stems etc., it erects its penis or peniform clitoris. I find this hard to interpret, but since pasting is sometimes done socially it could be that the individual concerned is ‘apologising’ in a way to superiors in olfactory range. Please bear in mind that when one individual attacks another, ‘The anal pouch may be rhythmically opened and closed at the same time’ (Estes 1991).
 
And it is interesting that, although so specialised for olfactory communication, the spotted hyena does not cock its leg to micturate as dogs do. Instead, micturition is a haphazard act, often done while the animal is lying down, so that the urine soils the fur on the flanks. This is often sniffed by others, particularly males getting information about females without approaching them too closely for safety.
 
The spotted hyena does have submissive signals: ears flattened, fear grimace, hindquarters lowered and tail clamped. Also carpal-crawling and grovelling. The spotted hyena has complex body language and audial language and so does not need its clitoris as an organ of ‘submission’
 
Inability to accelerate well in spotted hyena: not only tarsal but also carpal joint peculiar in locomotion:
 
I now realise that the spotted hyena has odd carpal joints as well as tarsal joints. This point is not original (please see mentions by Richard Estes below), but I don’t think enough has been made of it in the literature.
 
The tarsal joint of the spotted hyena (and also the brown and striped hyenas) is hyperextendable relative to e.g. felids and canids, perhaps compensating for the shortness of the hindlimb relative to the forelimb and allowing an economical lengthening of the stride in endurance running – but at the expense of acceleration.

Essentially, the hock of the spotted hyena is weak but flexible, which is good for an enduring canter but bad for the powerful acceleration needed to get away from an attack from the lion.
 
On a detailed reading of Estes today, I notice that there’s also something unusually flexible about the carpal (wrist) joint. Although this is not evident in photos of the spotted hyena in running gaits, it comes out in two situations: abject submission and juvenile locomotion within narrow tunnels.
 
I mentioned yesterday that the spotted hyena has no need for an ‘organ of submission’ because it has such an effective repertoire of communication to express submissiveness. In abject submission, the animal grovels by crawling on its wrists, as if to lower itself from an animal with the relatively long forelimbs of the species to an animal more stumpy. This is accompanied by certain pleading vocalisations that seem to be uttered in no other situation. Carpal-crawling is the closest thing to begging for one’s life in the language of the spotted hyena.

My point is that, as far as I know, dogs do not perform this ‘gait’, because their carpal joint is not flexible enough for this. It’s one thing for an animal to go down on its ‘front knees’ (i.e. to rest its carpal joints on the ground as warthogs do when foraging, or as wildebeests do when sparring), but it’s something else to locomote for any distance or at any speed in a carpal crawl.
 
The original point I’m making here is that the flexibility that allows the spotted hyena to carpal-crawl is also at the expense of the power needed to accelerate well. I.e. in both hind- and forelimbs, the spotted hyena has specialised tarsal/carpal joints that are designed for endurance running at the expense of acceleration, and carpal-crawling is a corollary of this.
 
The small juvenile hides for most of the time in tunnels too narrow for adults – including its mother – to enter. So narrow, indeed, that the baby itself has to squeeze through them by carpal-crawling. I have not heard of anything similar in other carnivores such as canids, although I may be wrong here.
 
The interaction between the spotted hyena and its prey species seems to provide evidence for this specialisation for endurance running at the expense of acceleration. Estes states that ungulates, when approached by the spotted hyena: ‘...hardly move out of the way of a walking hyena, flee in the opposite [what does he mean by this?] direction for 50-100 m, enabling the hunters to detect any stragglers. Why prey species allow hyenas to get closer than other large carnivores remains unclear.’
 
My answer:
Because the prey animals know that they can easily beat the spotted hyena in acceleration if it dashes forward, and because the whole game at that point is for the hyena to choose the genuinely weakest individual in the congregation. It is in everyone’s interests that the hyena has the chance to make a proper inspection, so that genuinely fit individuals of the prey species do not get falsely chosen for an endurance race.
 
Although all the facts seem to be known, Estes does not seem to have put together the full picture of tarsal/carpal specialisation in the spotted hyena and the evidence it provides of reliance on endurance running and the availability or large expanses of flat land and treeless vegetation. The association between the spotted hyena and treeless grassland is evident not only in Africa but also, via the palaeontological/archaeological records, in the former habitats of the species in Europe and China.

This is a species specialised for ‘open plains’ and ‘plains game’, and I suggest that this is a crucial clue in interpreting its genital peculiarities.

What I am hinting at is that the spotted hyena is extremely adapted to a far-ranging mode of hunting different from that of felids and canids, and for this to work depends on a strategy in which the juvenile is anchored to one spot but can nevertheless rely on its mother’s milk.
 
https://books.google.com.au/books?id=g977LsZHpcsC&pg=PA334&lpg=PA334&dq=carpal+crawling+estes&source=bl&ots=1wpTSA2uJb&sig=-JWu3hc9kbeu8tEep0BKeLUHM2Q&hl=en&sa=X&ved=0ahUKEwixl4Pz_b3JAhXGJqYKHdAtCA0Q6AEIGzAA#v=onepage&q=carpal%20crawling%20estes&f=false

https://books.google.com.au/books?id=Xqp7poFviNcC&pg=PA282&lpg=PA282&dq=carpal+crawling+estes&source=bl&ots=zbFT-JToS0&sig=4givFrhbvSgEtmZVMMRR4GuxC48&hl=en&sa=X&ved=0ahUKEwixl4Pz_b3JAhXGJqYKHdAtCA0Q6AEIHjAB#v=onepage&q=carpal%20crawling%20estes&f=false
 
I now realise how wrong I was in suspecting that the spotted hyena is an important predator of rock hyraxes.
 
The spotted hyena, I now realise, is specialised in terms of habitat: it likes plains covered in treeless grassland.

It inhabited such country in both Africa and Eurasia (as far east as China) and is much better-characterised as an animal of treeless grassland than an animal of the African savanna. It’s specialisations for ‘open plains’ and the typically migratory ungulates roaming such environments include its extreme cursoriality (exceeding even that of canids) and its specialisation on lactation as a reproductive strategy. Its peculiar carpal and tarsal joints and sloping back, and its udder, are part of this specialisation for treeless grassland on flat ground, in which mobility is crucial.

As I see it, this specialisation has been taken to lengths where other things have been compromised: acceleration and an ability to negotiate broken terrain. I suspect that the spotted hyena is one of the poorest of large mammals in African savannas in climbing rock outcrops or hunting on rocky slopes, owing to its skeletal and locomotory specialisations.

So the idea of this species hunting rock hyraxes on rocky outcrops is, I now see, probably misled.
 
None of the other mammalian predators in the past and present environments of the spotted hyena are specialised for migratory plains game. The cheetah has little capacity for mobility in this context. The African hunting dog is more at home in woodland than in treeless grassland, although it does irrupt in treeless grassland for a while and then disappear (experience in the Serengeti ecosystem). The lion is poorly adapted to treeless grassland, compared to the spotted hyena.
 
Part of this ecological strategy is that the populations of the spotted hyena tend to be less subject to fluctuations than those of the other large carnivores, all of which are more fecund but shorter-lived and less able to learn from experience. Part of the niche of the spotted hyena is the maintenance of relatively consistent densities (or perhaps I should say sparsities?) of population.
 
I suspect that, if we think this through properly, we will find that the peniform clitoris of the spotted hyena can also be explained in terms of this specialisation for migratory plains game.
 
For example: each individual of the spotted hyena depends on its home range, which is shared with all the members of its clan. There is never any time in the life of an individual when it can actually experience its clan as a unit, and so each time two individuals cross paths there is the question of whether the individuals belong in the area or are interlopers, which would be chased off or killed. Clan membership must be tested each time, and it pays the individual to ‘demote itself’ at such meetings because this gives it the benefit of the doubt.

The function of the greeting ceremony could ultimately be to prove clan membership, something otherwise not easily established given that each individual in a clan of say 50 individuals has to be able to recognise so many other individuals without having frequent opportunities to meet all in one place at one time.

I wondered, above, whether the males greet each other similarly to the way females greet each other, i.e. with the inferior individual most likely to erect the penis for olfactory examination. I suspect that this is true, but I now see that the whole question is rather irrelevant. This is because the hierarchy among males has a simple rule: priority of entry into the clan in question. Males leave their natal clan and enter a new clan, in contrast to females which tend to remain in their natal clan. Among males, it is the case that the hierarchy is essentially a queue. So the whole question of olfactory examination has less complexity than among females.

This does, I think, mean that it is the females who set the overall rules, and the important overall rule is that phallic erection is a sign of inferiority. I do think this applies, effectively, to males as well, which means that the normal order of things among mammals has indeed been perverted, as it were, in the spotted hyena.
 
Secondly, I made the point (above) that clan members in the spotted hyena never have a chance actually to see the whole clan together. I’d like to contrast this with e.g. baboons, which have clans of similar size and social complexity, and in which the politics are equally complex.

My point is that any individual baboon has frequent opportunities to see his/her whole clan as a real entity, because the clan tends to move around together and congregate during activities and rest. Not so for the spotted hyena: the literature frequently acknowledges the similarities with baboons, but does not stress enough, to my mind, the fact that the spotted hyena must construct the composition of its clan as something ‘virtual’ in its mind in a way that baboons do not need to do.

Thoughts on male competition in spotted hyena:
 
In the spotted hyena as in all other mammals, there are superfluous males. This is simply because it takes only a few males to inseminate the whole population of females. It is intrinsic to masculinity that males must compete with each other more than females do. All females can contribute by producing offspring but many males are potentially superfluous.
 
So, there must, logically, be some form of reproductive competition among males in the spotted hyena, despite the emphasis in this species on competition among females as part of a life history strategy uniquely centred on lactation.
 
Males are so thoroughly inferior in the society of the spotted hyena, relative to females, that it puzzling why there are so many males in each clan (the sex ratio is very approximately 50/50). Why are the males not reduced by a skewed sex-ratio at birth, or at least by infanticide or differential mishap of males at the juvenile stage? What use are most of the male individuals and how do they actually compete reproductively?
 
Until we understand this we will not fully understand the life history strategy of the spotted hyena.
 
It seems to me that there are only two real opportunities for competition in the lives of males in the spotted hyena, and I’ve never seen this put succinctly in the literature in the way I’m about to put it now.
 
Firstly, in the natal den most male individuals will find themselves in competition for the milk of their mother, with a sibling which is either male or female. The normal litter size is two and, because the natal sex ratio is basically 1:1, the chances are one member of the litter will be male. Regardless of the sex of the sibling, the male neonate must assert itself for priority of access to a teat. There is a real struggle at this stage, because if the male is dominated by its sibling there is a real chance that it will starve, or at least be ‘runted’.

As I understand it, the mother will not and/or cannot ensure that both siblings get an equal share of the milk – despite the fact that she has two functional teats and so on the surface of it there should be no problem with each sibling getting an equal share of the milk.
 
I would go as far as to say that competition between individuals is most intense, in the whole life of this species, at this stage when siblings sort out which individual is superior and which is inferior. There does not need to be direct siblicide, of the sort known in eagles; all that needs to happen is for the superior sibling to dominate the inferior sibling to the degree that the latter does not get as much milk, and there’s a slippery slope from there – not necessarily towards death but in the sense of being set back in life. This within-den competition determines

• whether the male individual will survive at all,
• how quickly it will grow, and
• if the litter consists of two surviving males, which one is superior – probably for the rest of its life.

Secondly, once the male individual grows up it must leave its natal clan if it is to have any chance of reproducing. Male offspring retain a high rank in their natal clan if their mother has high rank, but the trouble is that they tend not to be accepted as sexual mates within that clan.

So, their high rank among males is only good for getting them big and strong at maturity as soon as possible, and then they must start again in a new bout of competition via priority, by entering a new clan. This is usually at about age 2 years.
 
In the new clan, the male hierarchy is simply a queue, i.e. chronological. Whichever male individual entered the clan first tends to be superior. There is no real competition among males, in the sense of ‘queue-jumping’. So it follows that there’s not that much going on politically among males. They all know their place, because the rules are so simple.

Of course, there is lots of 'brown-nosing' by males of the superior females, getting in the females’ good books over a period of years so that at some later stage a mating opportunity can be consummated. But that is just par for the course as a long drawn-out process of courtship. Courtship, whether brief or protracted, is something different from competition among males. The competition among males, for the privilege of being able to court a female in the first place, is reduced to the relatively simple mechanism of a QUEUE in the spotted hyena.
 
So, to get ahead in life, the male must succeed at two crucial junctures.
 
Firstly, it must survive competition in the natal den, in which its strength as an individual is really tested from the start (which is why it is born with erupted canines despite the likelihood that it will not use these canines to kill prey until it is several years old). We must assume that every reproductively successful male in a clan has by implication passed this test at the infant stage, i.e. that all inferior individuals of the male sex have been rendered ultimately unsuccessful reproductively in an extremely precocial process of competition.

Even if both siblings survive in a litter consisting of two male individuals, growth is likely to be faster, and body condition superior, in the individual which establishes superiority, giving him access to more than his share of the mother’s milk. The superior individual male is, then (I infer) likely to be in a position to leave the natal clan at say 1.8 years old, compared to his brother who is ready only at 2.2 years old; this can make all the difference to the lifelong reproductive success of the male individual in question.
 
This is worth emphasising because I’ve not seen it stated clearly enough in the literature. In most mammals, the most intense competition among male individuals is in sexual maturity. In the spotted hyena, the most intense competition among male individuals is instead likely to be in infancy. That’s really worth pondering deeply, not so?
 
In that sense, the male in the spotted hyena has not only been sidelined in the way generally known. The male has also, in a limited sense, been ‘infantilised’. What normally takes place between machos with big bodies and bigger egos, in the steroidal steam of full maturity, has been relegated in the spotted hyena to the nearly blind conditions of a narrow tunnel shortly after birth, the infants still all-black and groping about in the dark, carpal-crawling and perhaps tarsal-crawling as well (something I’ve not seen mooted) as they jostle with each other in a rather grim parody of the carefree play we would consider normal in infancy.

Masculinity in the spotted hyena has been inverted not only in the sense of the male being generally inferior to the female, but even in the sense that competition among male individuals – ultimately for the prize of eventual copulation – has been flipped from maturity to infancy.
 
The second crucial juncture is the departure from the natal clan. This takes courage, because it’s perfectly possible that the newly mature male individual will be killed as soon as he appears in any new clan. He must leave the security of his mother’s protection, find a new clan, and grovel abjectly there to be allowed to survive. If his life is spared, he enters a queue which essentially fixes the trajectory of his status among the male individuals of the new clan for the rest of his life.
 
What I’m building here is a case that in the male as well as in the female of the spotted hyena, there is life history strategy by ‘bottleneck’.
 
The natal den is, as it were, a bottleneck from which only the strongest male individuals will emerge as reproductively successful. Entering a new clan also, as it were, involves a bottleneck, because what’s important is to make that move as early as possible. The faster the male individual can grow, the sooner he is likely to be ready to make that all-important move. The sooner he gets in, the greater his chances of reproducing eventually.
 
To state it clearly:
According to my reading of the literature, it matters little how well the male individual competes with other males as a juvenile more than a few months old, because his rank is determined by that of his mother. So after his initial crucial self-assertion as an infant, out of reach of his mother in a narrow tunnel that even his mother cannot enter, there is little he can do to promote himself until after puberty. Then, after puberty, he has one further shot at promoting himself, by summoning the courage to enter a new clan as soon as possible.

Then, arguably for the rest of his life (which is a long life by carnivoran standards), that’s it; he knows his place relative to the females and the other male individuals in his lifelong clan membership in the sense that it is pointless for male individuals to spar/jostle/struggle amongst themselves directly.
 
The point I am making here is that it is not that there is no competition among male individuals in this species with its overwhelmingly female-biased society; it is that the competition among male individuals is concentrated in two ‘bottlenecks’, the first involving a contest to see which individual can get FIRST access to its mother’s teat, and the second involving a contest to see which individual can get FIRST access to a new clan.

Although I think there is real physical struggle in the natal den, there as well the main question is one of priority. Whichever individual infant emerges from the narrow tunnel first and crawls over to its mother’s teat is the one that is more likely to reproduce successfully in the eventual course of its life.
 
Male success in the spotted hyena is, I argue, all about two struggles for priority in the whole lifetime: the first shortly after birth – for access to the mother- and the second shortly after puberty – for emancipation from the mother.
 
Although everything I’ve proposed here is based on the literature, I have not seen it put this way in anything I have ever read.
 
None of this explains the central puzzle of the species: why on Earth the spotted hyena has created for itself the bottleneck of such a narrow birth-canal. However, it does seem to emphasise that the life history strategy of the species is all about bottlenecks and critical junctures.

Central puzzle about spotted hyena:
  
Although the genital peculiarities of the species have been much-discussed, everyone seems to have missed the central puzzle of the species.
 
This is that the spotted hyena has chosen, evolutionarily, to create for itself an apparently unnecessary bottleneck for the birth process: giving birth through a narrow passage. The fact that this passage is a clitoris, or penis-like, or whatever, is fascinating but not central. What is central is that the species has created for itself this narrow constriction through which every member of the species must enter the world.
 
Why on Earth would a species do this?
 
I am struck with the comparison between the spotted hyena and its major prey, namely wildebeests.
 
Both the spotted hyena and wildebeests are specialised for life on plains with treeless grassland. Both have sloping backs with relatively short hindlimbs, and a cantering gait designed for maximum economy in long-range movement as part of a system of seasonal migration. Both are sexually monomorphic (females of wildebeest have horns, manes, beards, and even a slight bump at the position of the penis).

Both have precocial neonates: in the case of wildebeest the newborns can run within minutes of birth, dispensing completely with the hiding stage normal in ruminants. In the case of the spotted hyena the newborns already have canine teeth big and sharp enough to fight with siblings, and claws strong enough to dig their own tunnels for refuge.
 
But when it comes to parturition the parallels break down. Wildebeests, unsurprisingly, have arranged for themselves a birth canal suitably wide and distensible for the task at hand. There is no difficult labour; the birth canal allows the large leggy neonate to slip out into the world so easily that it almost seems to fall out of its mother. In the case of the spotted hyena, the species seems to have gone out of its way to create for itself the hardest possible pathway.

Birth involves an implausible dilation of a passage as narrow as the urethra; even if successful it always requires a several-cm tearing of the tissues, which never fully heals. At worst, the mother and offspring can die in birth.
 
I think that when we finally understand exactly why the spotted hyena has chosen to ‘give birth through a penis’, we will understand the species deeply. But first, someone needs to pose the question clearly.

Original point re ceremonial micturition in spotted hyena:
 
I have never seen the following pointed out in the literature, but when I think about it this is important to an understanding of the sexual monomorphism of the spotted hyena.
 
In the domestic dog, as everyone knows, the male cocks his leg while micturating, whereas the female squats instead. We humans notice this pattern easily because it’s essentially what we ourselves do: we direct the stream of our urine so that it does not wet our body including our legs. Everyone also understands that, because urine is smelly, the domestic dog – at least the male – tends to cock a leg at some object above ground level where the urine can be deposited for the future information of another individual which passes by. All of this is ‘too obvious for words’.
 
And so, when we learn that the spotted hyena has a peniform clitoris and that it is the female which is dominant and assertive in the society of this species, it is easy to assume that the female of the spotted hyena cocks her leg while micturating, for much the same reasons as a male dog would. Especially when we learn that that mutual sniffing of the groin in the spotted hyena always involves cocking a leg.

Knowing that the spotted hyena is an unhygienic animal, we might doubt that hygiene is the reason, but we could easily assume – especially when told that the main function of the peniform clitoris in this species is olfactory – that the female spotted hyena scent-marks objects in the environment with her urine.
 
And so it is surprising that such is not the case.
 
As far as I can see, the spotted hyena never cocks a leg while micturating, in either male or female.
 
This species does not scent-mark objects in its environment with urine, despite elaborate and posturally distinctive marking by means of the everted anal glands – and despite erecting the phallus partially while pasting with the anal glands in this way.
 
Indeed, as far as I know the species does not even extend the phallus in the form of a urinary spout while micturating, instead soiling its body with its own urine (the latter being true in the female although this needs confirmation for the male).
 
This raises a question I’ve never seen asked before: why does the peniform clitoris of the spotted hyena contain the urethra at all? It is not the case that the mammalian clitoris, by default, contains the urethra. It usually does not, the urethra being a separate opening (as in humans) although the clitoris is in many species effectively a ‘drip-tip’ for the urine.
 
Of course, it is no big deal that the clitoris of the spotted hyena contains the urethra, because this does not mean much disadvantage. But the point remains that an evolutionary decision has been made to incorporate both the birth canal and the urethra in the clitoral tube. The first decision is downright perverse, because it seems life-threatening. The second decision is surprising because there seems to be no advantage in passing urine through the clitoris as opposed to some other nearby location in the groin.
 
All of this seems to have gone over the heads of all the experts on the spotted hyena, who I don’t think would dispute the facts I’ve presented here, but would probably look blank at the questions I am raising about them.
 
I notice for the first time the following coincidence: erection of the peniform clitoris is not only performed by inferior, not superior, individuals in the spotted hyena, but has nothing to do with social value of urine in olfactory communication. Both are counterintuitive, not so?
  
Conventional view:
In the spotted hyena, the large clitoris is penis-like to the degree of incorporating the urinary passage, and the clitoris is used for olfactory communication accompanied by a leg-cocking posture. This can be explained by the social system of the species, in which the female looks and acts masculine.
 
New interpretation:
The urethra of the female spotted hyena is part of its peniform clitoris despite, not because of, the use of the clitoris for olfactory communication. This is because the female of this species does not cock its leg while micturating, does not mark objects in its environment with urine in the way it does with the secretions of its anal glands, and may not even use its clitoris as a spout for urine if the clitoris remains fully flaccid during micturition. (plus optional addition of the sentence marked in bold a few lines above).

Re limits to human fecundity compared with spotted hyena:
  
How many children can a woman produce in her lifetime? The answer is ‘more than I thought’.
 
There is a factoid going around that the record number of surviving offspring from any one human mother is 26. However, when I tried to verify this at
https://en.wikipedia.org/wiki/List_of_people_with_the_most_children I failed. The big surprise to me was how many times women are reputed to have produced far more children that two dozen. I don’t quite know what to make of these tales of extreme fecundity.
 
My reasoning for now: if a woman starts breeding at 18 years old and reaches menopause at 48 years old, then she has three decades in which to produce children. If she gives birth every 1.5 years on average (which seems reasonable although strange to us in our modern societies) and all her litters consist of one only, then she should be able to produce 15 children.

In good circumstances, many or most of these might survive. So I can understand a women, dedicated to breeding, producing a dozen surviving children. For her to produce many more would require litter sizes regularly to be >1, which could happen in certain individuals with a proclivity for twins and triplets.

However, the greater the litter size the smaller the neonates and presumably the less the survivorship past infancy. So any number above say 20 children produced by one woman in her lifetime would, to me, seem remarkable and atypical of our species.
 
The spotted hyena lives far shorter than us, perhaps up to 25 years if all goes well. If the female starts breeding at two years old and has a litter every 1.5 years like the human female (which seems reasonable because the spotted hyena can be weaned as late as 1.5 years old), and if her average litter size is two, and if she continues to breed into senility, then she should be able to produce up to 15 litters.

The reproductive system in this species tends to favour the survival of only one offspring per litter, which means that the full reproductive performance of the spotted hyena is in the same ballpark as that of the human. The human species lives longer but has menopause; the spotted hyena has on average double the litter size but more unfairness between siblings. In both species it is conceivable that an individual female can produce up to 20 offspring in her lifetime, all of which survive to reproductive maturity themselves.

However, this would take extraordinary good fortune, and could never be the norm because neither species is functionally polytocous and both have a relatively long combination of gestation and lactation.
 
The bottom line seems to be that the spotted hyena is about as slow-breeding as the human species? If so, this seems noteworthy in view of the fact that the two species have approximately the same body mass, and are potential competitors for game animals including their bones?

To clarify the bottom line above:
When I suggested that the human species and the spotted hyena are about equally slow-breeding, I meant a particular rate, viz the number of offspring produced by a given female during her life.

Of course the rate of reproduction per year will be greater in the spotted hyena than in the female. This is because

• although both species might produce two dozen surviving offspring per lifetime from an exceptionally fecund and successful female individual, the reproductive lifetime of the hyena is the shorter (not much more than 20 years, compared to perhaps 30 years in the woman), and
• the lifespan of the hyena is only about a quarter of that of the woman in optimal circumstances.

So there is no doubt that the hyena is more fecund than the like-size human per year on average, but my point below was that if this is viewed as reproductive rate per female lifetime the rates seem similar.
  
Something that I think would be believed by many or most who know anything about the spotted hyena is that the spotted hyena shows ‘sexual mimicry’ and that the peniform clitoris of the female ‘mimics’ the penis. Not so.

I have expressed dissatisfaction with the term sexual monomorphism. Although technically true, the sexual monomorphism is too easily misinterpreted (the more insidiously for the fact that this is usually implicit rather than explicit) to mean that the genitalia of the female are like those of the male. I think the truer interpretation of the same facts is that what is most remarkable is how functionally different the female genitalia are from normal mammalian male genitalia.
 
The reason why the claims of ‘mimicry’ of male genitalia by the female spotted hyena are misconceived is as follows.
 
Mimicry is essentially a functional thing, i.e. the object concerned gets an advantage from resembling the object that it resembles. By mimicking a toxic butterfly, a harmless butterfly implies a functional similarity, in this case toxicity (which is untrue). This is the correct use of ‘mimicry’.
 
This is not what goes on in the spotted hyena.
 
If it were a case of mimicry, then we would expect that the peniform clitoris would BEHAVE like a penis in e.g. the following ways.
 
The clitoris would be used for intromission. This is conceivable if one imagines that in the spotted hyena there might have been a matriarchal system in which a female ceremony/ritual of dominance consisted of rape. It’s interesting that there seems to be no recorded instance of female-on-female rape in the animal world, but if such a thing was possible it would be in a species with a peniform clitoris, not so? Even anal rape is conceivable given that the spotted hyena lacks a vagina in the conventional sense.
 
In fact, there is no such mimicry.
 
Secondly, the clitoris would be used as a spout for urine, particularly in scent-marking (as seen in the domestic dog). As far as I know, this is NOT what in fact happens in the spotted hyena. There is no mimicry of the penis w.r.t. micturition, other than the fact that the urine passes through the peniform organ (I suspect usually in its most flaccid state).
 
Thirdly, the clitoris would be used in the body language of self-assertion or the display of confidence of libido (as seen in primates including humans, signified well by the slang word ‘cock’ and ‘cocky’). In fact there is nothing ‘cocky’ about erection of the peniform clitoris and this has spilled over to some extent also the penis itself, in the spotted hyena. If anything, the clitoris is ‘anti-cocky’, i.e. its erection being a particularly clear signal of self-demotion rather than self-promotion.
 
Indeed, it is this very puzzle, i.e. that the clitoris of the female spotted hyena so closely resembles the penis of the male spotted hyena while NOT MIMICKING it, that is a central puzzle in our understanding of the species as a whole.
 
There is one limited aspect of functional similarity: the clitoris produces scent, much as the penis does. However, this is not enough to support a claim of overall mimicry. Besides, it’s logically dubious to claim that the organ needs to resemble a penis physically to give off the scents in question. The vulva of the normal female mammal is perfectly capable of giving off scents. So even here there is no strong case for mimicry.
 
And, as a clincher:
The fact that the spotted hyena gives birth through her clitoris is, in a sense, the ultimate proof of a lack of mimicry.

Firstly, the idea that the clitoris of the spotted hyena ‘mimics’ the penis implies that the female would get some advantage from its overall resemblance to the male. This makes no sense, because the male of this species is neither distinctive-looking nor worth resembling, from the point of view of the weaker sex.

If it were the case that the female was smaller and weaker than the male, then it might be logical to suggest that possession of a penis-like clitoris might ‘mimic’ the male to some advantage. But in fact the two sexes resemble each other in size and shape and pelage and colouration, so that there is no conceivable advantage in ‘mimicking’ what is in fact the inferior sex in this species.

Secondly, for most of its life the female spotted hyena carries an udder, so prominent that the peniform clitoris is rather sidelined as a conspicuous feature of the groin. What logic is there in the suggestion (implied, never explicit) that the female could ‘mimic’ the male by possessing something resembling (falsely) a penis sticking out of something resembling (truly) an udder?

If there is any mimicry involved, it would seem more likely that the clitoris is mimicking a teat. Compare this with a hypothetical animal in which there is a peniform clitoris and the mammae are located somewhere other than the groin (e.g. on the chest as in elephants). Were that so, there might be some prospect for a functional resemblance to the male. But in fact the conspicuousness of the udder outweighs that of the clitoris in most cases, and this makes the idea of ‘mimicry’ of a penis silly, not so?

(writing in progress)

Publicado el julio 16, 2022 08:11 TARDE por milewski