4 ms·

There is not a reason for everything. The spotted hyena is one of the most successful carnivores in Africa; yet females hyenas lack an external vaginal opening

by bambax 9y ago

There is not a reason for everything. The spotted hyena is one of the most successful carnivores in Africa; yet females hyenas lack an external vaginal opening and therefore give birth through their narrow clitoris (...). During parturition, the clitoris ruptures in order to facilitate the passage of the young, and may take weeks to heal. https://en.wikipedia.org/wiki/Spotted_hyena https://en.wikipedia.org/wiki/Spotted_hyena One can only imagine the extreme pain and difficulty involved in this; yet it's unlikely there's an evolutionary justification to be found. It's most probably an accident -- a quite unfortunate one for the female hyena.

gehwartzen 9y ago
One possible justification is that this genital configurations prevents forcible rape, as the wiki article points out. This allows females to have more control over the genetic traits of their offspring.
- xenadu02 9y ago
  That’s probably just a side-effect of the greatly increased testosterone in female hyenas. I don’t think anyone can really say whether the testosterone or matriarchal organization came first (or co-evolved).
- cratermoon 9y ago
  the term "forcible rape" is rife with difficult implications. "Many experts now believe that rape is best understood as an act of unwanted bodily invasion that need not involve force." http://www.nytimes.com/2012/08/24/us/definition-of-rape-is-shifting-rapidly.html http://www.nytimes.com/2012/08/24/us/definition-of-rape-is-s...
  - gehwartzen 9y ago
    I agree with you. Sorry if I wasn't clear, I just using the language in the wiki article. I guess the point is more that with a normal vaginal opening any male physically strong enough can impregnate a female. With the Hayena configuration my understanding is that the female has to consciously retract her clitoris to make impregnation possible at all. So yes the male could still coerce, through emotional manipulation or threat of physical force, a female to comply without direct physical force but I don't know how applicable that is to hayenas (or most non-human animals).
  - dogma1138 9y ago
    Since hyaenas are not going to promise to marry you or claim to be an Albanian prince to get sex forcible rape is pretty accurate.
grondilu 9y ago
IIRC, this also means that the first litter systematically dies off. I vaguely recall a guide explaining this during a SafariLive stream[1] 1. https://wildearth.tv/safarilive/ https://wildearth.tv/safarilive/
sliverstorm 9y ago
In general, vestigial traits hang around because there is little selection pressure against them, but new traits don't usually seem to show up & take over for no good reason.
twobyfour 9y ago
FWIW, it's now recognized that the parts of the human female anatomy that are sensitive to arousal (parts that are essentially analogous to the shaft of the penis and to the skin of the testicles in their sensitivity and in their ability to convey pleasure) surround the entire vaginal opening and portions of the vaginal wall. No, they're not as sensitive as the clitoris (and no, I don't think we know precisely how sensitive the hyena clitoris may or may not be) but human women also give birth through tissue that is dense with nerve endings and more sensitive to both pleasure and pain than, say, that on the outer surface of your arm.

by bambax 9y ago

gehwartzen 9y ago

One possible justification is that this genital configurations prevents forcible rape, as the wiki article points out. This allows females to have more control over the genetic traits of their offspring.

xenadu02 9y ago
That’s probably just a side-effect of the greatly increased testosterone in female hyenas. I don’t think anyone can really say whether the testosterone or matriarchal organization came first (or co-evolved).
cratermoon 9y ago
the term "forcible rape" is rife with difficult implications. "Many experts now believe that rape is best understood as an act of unwanted bodily invasion that need not involve force." http://www.nytimes.com/2012/08/24/us/definition-of-rape-is-shifting-rapidly.html http://www.nytimes.com/2012/08/24/us/definition-of-rape-is-s...
- gehwartzen 9y ago
  I agree with you. Sorry if I wasn't clear, I just using the language in the wiki article. I guess the point is more that with a normal vaginal opening any male physically strong enough can impregnate a female. With the Hayena configuration my understanding is that the female has to consciously retract her clitoris to make impregnation possible at all. So yes the male could still coerce, through emotional manipulation or threat of physical force, a female to comply without direct physical force but I don't know how applicable that is to hayenas (or most non-human animals).
- dogma1138 9y ago
  Since hyaenas are not going to promise to marry you or claim to be an Albanian prince to get sex forcible rape is pretty accurate.

grondilu 9y ago

IIRC, this also means that the first litter systematically dies off. I vaguely recall a guide explaining this during a SafariLive stream[1] 1. https://wildearth.tv/safarilive/ https://wildearth.tv/safarilive/

sliverstorm 9y ago

In general, vestigial traits hang around because there is little selection pressure against them, but new traits don't usually seem to show up & take over for no good reason.

twobyfour 9y ago

FWIW, it's now recognized that the parts of the human female anatomy that are sensitive to arousal (parts that are essentially analogous to the shaft of the penis and to the skin of the testicles in their sensitivity and in their ability to convey pleasure) surround the entire vaginal opening and portions of the vaginal wall. No, they're not as sensitive as the clitoris (and no, I don't think we know precisely how sensitive the hyena clitoris may or may not be) but human women also give birth through tissue that is dense with nerve endings and more sensitive to both pleasure and pain than, say, that on the outer surface of your arm.