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Why have female animals evolved such wild genitals?
- ttyp3 5y ago
- seattle_spring 5y ago
- mensetmanusman 5y agoWe don’t even understand how rocks evolved into life, so we will not know for quite some time…
- paulryanrogers 5y agoWhat is your threshold for 'knowing'? Evolution by natural selection has been witnessed in modern times. Is there some reason to doubt the fossil record evidence that life has repeatedly developed from simpler forms toward more complex? (Albeit repeatedly as changing conditions caused some mass extinctions.)
- frosted-flakes 5y agoHow, not if. What sparked the first forms of life? No one knows.
- nostromo 5y agoEvolution explains how life evolves, but doesn’t explain the origin of life itself.
- thaumasiotes 5y agoHm? Evolution explains why life evolves in particular directions. But it has nothing to say about how changes occur; instead, it assumes that changes occur and discusses which changes persist and which don't. From the perspective of "evolution", there is no difference between a strand of RNA mutating into a different strand of RNA and a cluster of vaguely RNA-like chemicals mutating into a strand of RNA. Those are both things that are outside the scope of evolutionary theory.
- kergonath 5y agoEvolution is just a fancy word we put on what we see in living things, but there is nothing magic in DNA or RNA. In an abstract sense, the emergence of some specific complex molecules from a bunch of precursors also is selection of the fittest (most stable, with the lowest energy of formation, etc). These are things at play in the production of amino acids in thermal vents, for example.
- thaumasiotes 5y agoIsn't that what I'm saying?
- kergonath 5y agoIndeed. I intended it more as a complement than an argument against your post.
- paulryanrogers 5y agoEvolution offers the most likely origin of life since it is simpler than all others that I've heard.
- tsol 5y agoYou can explain in detail how self sustaining life can evolve? Even the most die hard science minded people I know concede that's an unknown
- kergonath 5y agoIt’s an unknown in the sense that it hasn’t been verified experimentally and we lack many details, but there are still quite a few things we know. The fact that we are not certain is not an excuse to claim that god did it and it is a failure of science, or that it is unknowable.
- deleted 5y ago[deleted]
- tsimionescu 5y agoEvolution does not claim to explain the origin of life - only the, well, evolution of modern day species from primordial ones. The origin of life - that is, how the very first ancestor in the chain came to be from simpler chemical processes - remains an active open area of research. This isn't some faith based, moving the goal posts etc argument - its simple scientific fact: we don't yet know the chemical processes that can start with inorganic compounds and lead to a living cell. We will, some day, but we don't now.
- kergonath 5y agoMost likely, there is no origin of life. As in, there is nothing you can point to that is clearly alive and came from things that are clearly not. Although it is complicated, we know a bit about the chemistry of self-replicating molecules. Things like prions and viruses also show that the boundary between alive and not-alive could be much more blurry than what most people have in mind when discussing such things.
- jazzyjackson 5y agoEver since bjork's "biophilia" album I have considered it a gradient between crystals and biology: they both use atoms in their surrounding to create copies of their structure. Stone does so in a temperature gradient in the environment (atoms crystallizing as they precipitate out of solution) while Life is able to store enough energy in itself to impose structure (trading energy for entropy) on surrounding atoms even when the environment would otherwise dissolve it. The threshold for 'life' is replicating even when conditions are not perfect, that's survival. (on another note, we would never have discovered DNA if not for the same x-ray techniques being used to analyze the symmetries of stone)
- robbedpeter 5y agoWe do know, though. We know the evolution of elemental matter, from the big bang through the formation of the solar system through the birth and the tectonic history of earth. We know that a particular combination of energetic environments and chemicals allowed a self reproducing process to take hold at least once. Because of the chirality of the chemistry of life, it's more likely that it developed on the surface, where solar radiation would select in that way, b but it could also have been thermal vents, underground springs, undersea volcanoes, or any of a set of locations that had the durability, energy, chemical availability, and border conditions that allowed cyclic processes to run the experiment a sufficient number of times for "life" to take hold. We're missing a tiny blip of specificity in the history of life, but there's not anything particularly mysterious about it anymore. It's chemistry and time and probably vast scale and chaotic processes, but fundamentally and simply, it's a matter of chemistry and probability. There's no reason to ascribe to life life any special mystery over any other dynamic processes, like tides or orbits. We won the existence lottery, nothing more or less.
- robbiep 5y agoSurely the OP is aiming for a god of the gaps argument
- robbedpeter 5y agoYes, it had that flavor to it, which prompted my response. Like minds as consciousness radios - we don't know how cognition works, but we know the brain is doing it. I'm arguing against mysticism, not curiosity or wonder at the awesomeness of the universe.
- mensetmanusman 5y agoNo, was just poking fun at these tautological pieces trying to explain everything like evolution has some goal in mind. :)
- tsol 5y agoA tiny blip called "how the entire thing started in the first place". This is a weak argument, honestly. The truth is there is no answer currently.
- unfocussed_mike 5y agoThis is literally not the preserve of evolution (as a concept or as a formal area of study). The relevant study is the field of abiogenesis: https://en.wikipedia.org/wiki/Abiogenesis https://en.wikipedia.org/wiki/Abiogenesis
- mensetmanusman 5y agoSeems to be a blurry boundary. Chemists talk about evolving reactions, people study the possible routes for rock chemistry to evolve into cells (abiogenesis), etc.
- nemo44x 5y agoI just wish the cultural revolution wasn’t so vapid and superficial.
- jakeinspace 5y agoCare to explain what you mean by that statement?
- nemo44x 5y agoSure - the article is written in the language and tone of a 9th grader. It’s a trite approach and although I get the mass appeal perhaps, it’s rather boring.
- TheDesolate0 5y ago
- toiletfuneral 5y ago
- deleted 5y ago[deleted]
- happytoexplain 5y agoIt seems pretty clear, and reasonably engaging. Plain, at worst. Are you sure you're not just a fan of flowery language? Also, what cultural revolution is the grade level of this writing related to? That's a pretty cryptic implication.
- Chris2048 5y agoI assume you mean: > He suggested that perhaps the male was responding to female preference—wink-wink, nudge-nudge—but hadn’t bothered to actually examine the female. I think "wink-wink nudge-nudge" is an unfair characterisation of someone's motivation to dissect duck genitals. It's a statement about evolutionary pressure, not a bawdy joke.
- tantalor 5y agoThe image appears to show spirals in the same direction, not "opposite".
- moron4hire 5y agoUhm, no. Look again. The easiest way to tell is to think of the spiral as stacked, linked slashes like \ and /. Which direction does the top layer go? For the vagina, it's going /. For the penis, it's going \.
- tantalor 5y agoYou're right! Thanks
- Lacaranian 5y agoI do wonder how "normal" human genitalia is compared to the vast majority of the animal kingdom. Though is that simply anthrocentric?
- tomrod 5y agoProbably worthwhile to consider it as familiarity bias -- as claimed by the article, the male researchers missed the vaginal shapes, so it's not just anthropocentricism.
- samatman 5y agoMany placental mammals, including the other great apes, have a baculum, while humans do not. I'm not even sure how to start comparing human genitalia to those of jellyfish or tubular worms, to be honest. The animal kingdom is quite broad.
- shagie 5y agoThe paper you are looking for is http://artemis.austincollege.edu/acad/bio/sgoldsmith/abpdfs/Gallup_et_al_2003.pdf http://artemis.austincollege.edu/acad/bio/sgoldsmith/abpdfs/...
- jug 5y agoI've heard humans have larger penises in proportion to our size than usual with mammals. Not sure how unique it is but the human glans is speculated to be shaped like it is to scoop out sperm from competing males. Since human vaginas aren't "wild" like that of a goose, maybe that is how we have evolved to handle competition? This must go far back though, way before we became humans...
- vonseel 5y agoWell, that’s a disturbing and quite gross image.
- asdff 5y agoArms race with the penis.
- gorgoiler 5y agoAnd fruit flies like a banana!
- tomrod 5y agoFascinating article. I'd heard about ducks before, but the complexity is really telling. I'm not sure I fully appreciate the evolutionary pressure in the bird's "arms" race, in that the female duck chooses mate despite violent competing males. Up to 40% die in the violence -- would that not put evolutionary selection in favor of females that lack resistance?
- simulate-me 5y agoThe article said up to 40% of matings were forced, not that 40% of female ducks die from forced matings.
- tomrod 5y agoFair. But even a non-trivial amount dying from forced mating would push evolutionary pressure, right?
- deleted 5y ago[deleted]
- the_af 5y agoI just did a ctrl+F and the article doesn't mention ducks dying at all.
- mxkopy 5y ago>In some cases, the female genital tract prevented the penis from fully inflating, and was full of pockets where sperm went to die. I think this is what they mean. Not offspring dying per se, but still an evolutionary pressure
- mbreese 5y ago> This often leads to a violent struggle, in which males injure or even drown the female. In some species, up to 40 percent of all matings are forced. There is no indication of the rate of drowning, but it would be a constant risk across all females, so no real evolutionary pressure would be evident (aside from a risk to the species as a whole). That is to say: the rate of drowning for females would have to be very low, otherwise the species would fail. If the rate was too high, you’d expect to see a counter pressure to have a higher rate of females born versus males. The point here is that as reproductive structures evolved, the female developed equally complex structures. She might not a choice in if mating occurs, but she does have a choice in whether a particular male fertilizes her eggs. That is the evolutionary pressure… not in response to death from forced mating. > Whatever the females were doing, they were succeeding. In ducks, only 2 to 5 percent of offspring are the result of forced encounters. So regardless of if the mating was forced or not, female ducks are quite successful in choosing who fertilizes her eggs.
- vmception 5y ago
- eyelidlessness 5y ago> suggests that the females have selected for traits they hate Selected for rejection in reproduction. But the term “select” here has a particular jargon meaning that doesn’t line up with how you seem to be using it. > collective eugenics Choosing breeding partners isn’t a eugenics program no matter how you try to frame it, that’s just mating. Evolutionary biology especially isn’t, it’s a process that happens generationally based on which genes continue to propagate. Certainly many species consciously prefer outcomes for their offspring, but they’re not (to anyone’s knowledge so far as I’m aware) making those choices for the whole of their social organization or species.
- vmception 5y agoI’m talking about evolutionary selection in the context of pressure for some genes to propagate, that is the jargon yes? I’m also acknowledging that an individual can influence that when many individuals are doing the same thing
- mxkopy 5y agoThere is also the reverse, males can be selecting for traits that make it easier to propagate their genes... that's how I read the result. The more 'endowed'/aggressive the male is, the more complex the vagina becomes to retain some preference in gene retention. >I’m also acknowledging that an individual can influence that when many individuals are doing the same thing The individual can't influence anything on evolutionary scales EDIT: "Retaining preference" is an incredible mischaracterization and an artifact of my not being a biologist. What I'm sure is actually happening is aggression /'mating through endowment alone' is detrimental to the well being of the female, which is detrimental to the well being of the offspring. What is interesting though is that instead of such offspring dying and aggression/endowment being selected against, these traits stay around long enough for there to be some evolutionary pressure for females to adapt around. I guess this kind of makes sense since aggression and physical size are advantageous in fights and whatnot, so there is a selection process going on independent from the mating process of that species
- alexklark 5y agoBrennan dissects a female coachwhip snake in her lab at Mt. Holyoke College in Massachusetts in September 2021. “This is my happy place,” she says. Brennan really love science. And genitals. And vivisections.
- ZGDUwpqEWpUZ 5y ago"Vivisection" involves a living creature.
- kergonath 5y agoNothing wrong with loving science, genitals, or dissection…
- rendall 5y agoThe imagery and jokes in that article are pretty repulsive. And funny. > "...there is a huge gaping hole in our knowledge of this very fundamental part of bird biology" > Brennan’s husband is used to these kind of excursions: “He brings me roadkill as a nuptial gift,” she says.
- moron4hire 5y ago
- dzink 5y agoThe role of gender in the algorithm of generic selection seems under explored. The males in many species compete to match some criteria of quality observed by females of that species. In some it’s colors, in others voices, boldness, strength, demeanor toward the female, physical competition against other males, the nuance is very rich. But the ability and responsibility to choose the best candidate is core to the female biology. Even down to the egg - the most persistent sperm doesn’t win, but the one approved by the egg with multiple testing criteria at play. In species where the males have evolved to be substantially more physically dominant than the females, you still see defensive mechanisms in the female reproductive organs. Why has biological gendering evolved to lead to this dynamic? Is it to enable one sex to vary wildly evolutionarily to respond to wildly changing conditions, while the other maintains the stability of the species? Is it because of what we’ve seen in human governments where division of power keeps one dominant bad leader from sinking the whole species? We saw GANs lead to tremendous boosts in creativity in machine learning algorithms. What if we apply these two-role algorithms (competing side and curating side) into machine learning and see where it takes us with agent systems for example? It’s already applied in business [Founders (competing), investors (curating)] and education [students and universities].
- mxkopy 5y agoI think it has to be all completely historical. In some species the male is the suitor, in others, the female is; and there are - or used to be, sadly - enough species for every linear combination of both possibilities. If I know anything about nature, it's that it's a brute-force optimizer for biological fitness. Every possible combination of traits could feasibly be tested on these scales.
- eru 5y agoI don't think dzink's point relies on whether the suitor is male or female, but that the distinction exists at all and is so widespread. > [...] and there are - or used to be, sadly - enough species for every linear combination of both possibilities. Extinction is sad, but there's still plenty enough species to make this statement true. > If I know anything about nature, it's that it's a brute-force optimizer for biological fitness. Every possible combination of traits could feasibly be tested on these scales. Not quite. Eg there's basically no wheel in nature, despite the structure itself being quite simple. That's mostly because it's hard to evolve in small steps.
- fractallyte 5y agoFrom a linked article (https://www.newyorker.com/tech/annals-of-technology/duck-sex-and-the-patriarchy https://www.newyorker.com/tech/annals-of-technology/duck-sex...): A female duck’s vaginal barriers cannot shield her from physical harm. On an evolutionary level, though, they protect her in another way—by allowing her to choose the father of her offspring. By using her vaginal barriers, she is able to maintain her sexual autonomy in the face of sexual violence. Our observations also revealed that when a female duck solicits sex with a chosen mate, her cloacal muscles dilate to allow uninhibited entry. The result is that, even for species in which nearly forty per cent of all copulations are violently coerced, only between two and five per cent of ducklings come from extra-pair matings. As a method of contraception, ducks’ vaginal barriers can be ninety-eight-per-cent effective... Is there an equivalent mechanism in human females? Why yes, there is. As one would expect, it's framed as a 'disorder': https://en.wikipedia.org/wiki/Vaginismus https://en.wikipedia.org/wiki/Vaginismus No one has seriously examined this as a natural defense against coerced sex, but maybe it's time...
- stkdump 5y agoIf I unserstand it right, this is in ducks a defense against contraception, not against coerced sex. Further, if this is supposed to be an argument against legal abortion (I heard before from the anti-abortion crowd, that the body has defenses against unwanted pregnamcy), then the question becomes if this really can be willfully controlled and if we really want to limit the choice making of women to that short period of time, when they are being violated. I think the disorder comes in, when women complain about it to their doctors, i.e. they are unable to control it. So I don't see a reason why it should be considered anything else in such circumstances.
- unfocussed_mike 5y ago> Further, if this is supposed to be an argument against legal abortion (I heard before from the anti-abortion crowd, that the body has defenses against unwanted pregnamcy) Most notably the GOP Rep[0] Todd Akin: https://en.wikipedia.org/wiki/Todd_Akin#Comments_on_%22legitimate_rape%22_and_pregnancy https://en.wikipedia.org/wiki/Todd_Akin#Comments_on_%22legit... [0] short for "reprehensible" in this case
- dang 5y agoAll: I realize the topic contains triggers and the article plays on them, but please contain yourselves.
- ggm 5y agoThere's got to be clear advantage, or at least no strong disadvantage across the morphological choices they are constrained to, in the forms. Isabella Rossolini aside, there's no dance here which is pure beauty, its form-follows-function all the way. Ducks are savage. York University where I studied, in the 70s had a huge shallow lake and it had a regrettable sexual population imbalance which caused fatalities. Randy drakes drowned the decreasing number of ducks. I think they had to do culling to fix it. You think nature would right itself, but in human time for small local populations sometimes it doesn't do a good job.
- throwanem 5y ago> You think nature would right itself Why think this? Populations and their environments constitute complex systems, not magical ones. They can self-correct, or not, just like how humans don't always manage to not develop cancer.
- giomasce 5y agoLetting a part of the population die, perhaps entire species or groups of species, is one of the way nature "rights itself".
- ben_w 5y agoDescribing a species wiping itself out as “nature righting itself” seems to me a bit like saying a shotgun is a cure for cancer.
- tjs8rj 5y agoWhy is that not accurate? Nature is just physical processes. Those physical processes taking their course is really all nature does. You could call it “righting itself” or “destroying itself” and I’d say you’re equally right, because the same physical process occurs without moral judgement, and your connotation is just you applying your human morality to the situation
- 5y ago
- robocat 5y agoInsect “penises” vary hugely, or even wilder variations e.g. detachable. “Insect genitalia have been the focus of much attention since the middle of the 19th century, when their taxonomic value to diagnose species with otherwise very similar [shapes] was recognised.”, “The structure of the female genitalia of Limnebius is poorly known, mostly due to the lack of sclerotized parts”. https://peerj.com/articles/1882/ https://peerj.com/articles/1882/
- brailsafe 5y agoIf I could straight up detach my genitals when I didn't need them I'd be golden.
- bigbluedots 5y agoThere's a song about that which was popular in the early 90s. https://en.m.wikipedia.org/wiki/Detachable_Penis https://en.m.wikipedia.org/wiki/Detachable_Penis
- AussieWog93 5y agoIncidentally, my favourite Wikipedia article is the one about the Drone Bee and his dick: https://en.wikipedia.org/wiki/Drone_(bee)#Mating_and_the_drone_reproductive_organ https://en.wikipedia.org/wiki/Drone_(bee)#Mating_and_the_dro... "Mating between a single drone and the queen lasts less than 5 seconds, and it is often completed within 1–2 seconds. Mating occurs mid-flight, and 10–40 m above ground. Since the queen mates with 5– 19 drones, and drones die after mating, each drone must make the most of his single shot. The drone makes first contact from above the queen, his thorax above her abdomen, straddling her. He then grasps her with all six legs, and everts the endophallus into her opened sting chamber. If the queen’s sting chamber is not fully opened, mating is unsuccessful, so some males that mount the queen do not transfer semen. Once the endophallus has been everted, the drone is paralyzed, flipping backwards as he ejaculates. The process of ejaculation is explosive—semen is blasted through the queen’s sting chamber and into the oviduct. The process is sometimes audible to the human ear, akin to a "popping" sound. The ejaculation is so powerful that it ruptures the endophallus, disconnecting the drone from the queen."
- chmod600 5y agoStructurally speaking, it's easy to imagine a number of ways the female could have complete control over the process. But if we don't observe that complete control (at least not in most species), and instead it's more of an "arms race"; then it makes me think complete control is an evolutionary disadvantage. Is that true?
- mxkopy 5y agoI think at some point other limitations come into play that prevent it being an arms race. It would be quite funny, but unfeasible, for most of the male's physical development to go to their reproductive organs. At some point it would weigh you down, you wouldn't be able run fast and you'd get eaten...
- Fomite 5y agoOne thing to keep in mind is that evolution does not produce global optimums - only local ones.
- dmichulke 5y agoThat's kind of a hard thing to measure against, can you tell me of an example in real life where you know something is the global optimum?
- ben_w 5y agoThat’s basically why it does local optima rather than global. As for an example where you know the global optima: real life hill climbing rather than the blindfolded version used to explain the algorithm of the same name?
- Fomite 5y agoYou don't need to know something is a global optimum - you just need to know there's a slightly better at-least-local optimum with a decrease in fitness between that and where one is now.
- hypertele-Xii 5y ago
- gorgoiler 5y agoIn terms of evolution through the donation and acceptance of information carrying material, the most bizarre ritual I have witnessed is that of Developa Linuxia: git format-patch --stdout | mail ... | git am It is recommended that this be seen in the wild. The beasts that exchange material this way are rare and ancient but we are fortunate that it is easy to observe them performing their rites. They make a point of enacting them publicly, in open clearings know as mailing lists. You will note that, in comparison to more evolved techniques, what first seems like clumsy fumbling takes on a primal beauty of its own. These creatures are aware of more modern practices and yet they choose to remain in their own evolutionary niche, in part, because they lament the way in which Developa intercourse has been cheapened and corrupted by an unmentionable website named “something”hub.com.
- jeffrallen 5y agoAnd the real miracle of nature is all that is hidden in "dot dot dot". See "Mama Mia" by Abba et al for more information.
- hackernewds 5y agoIs this a GPT3 post? made zero sense
- oblio 5y agoIt's a highly geeky joke about the Linux kernel development process, which is quite antiquated.
- jelliclesfarm 5y agoIt seems fairly straightforward to me..when it is expensive to procreate due to restricted resources, procreation becomes picky. Birds are mostly monogamous because flying is very energy intensive and the male parent doesn’t want to waste resource on fledglings that isn’t his..obviously, exceptions exist. It is very costly to raise the young. Parental investment is high. It is different for birds that don’t fly. Water fowl especially have a different reproductive system. Because they don’t fly. This is true for all flightless birds. Even for birds like geese that only fly for seasonal migration. They get their food from the water. Ground dwellers have plenty of food and don’t have spend as much energy foraging for food as a bird that flies. Very few of them mate for life. Further: Galus Galus has different design than geese and ducks. Castrated roosters are called ‘capons’(French)…produces a nice soft fat capon for Sunday lunch. It’s genitalia is less developed than say..geese. As a chef, I knew how to sex identify geese/duck. water fowl genitalia is different than fowl. Most farmers know this as sex determination is key to raising animals for profit. With the exception of Pilgrim/Emden/White Italian and some Chinese geese where the autosexing is straightforward with feather colouring and down colour, most have to be identified while they are still goslings. Goslings can be gender identified as early as the first week and also when they are adults. Male adult penis is invaginated and like a corkscrew. Female organs has genital eminence. The breeding ratio is 1:3 or max 1:5. So it’s important to separate them as early as possible. Mammals are different..example: feline penii is barbed and most copulation results in kittens. A female cat can have a single litter with multiple tomcats. Male cats will kill kittens ..probably those that aren’t their own..because a lactating mother cat won’t go into heat. With insects like bees and mantii, the male often meets his end after sex. It comes down to energy needs and availability of resources. P.S: [..] Birds, she thought at the time, didn’t have penises. In her two years studying them at Cornell University, a world leader in avian research, she’d never once heard her colleagues mention a bird penis.[..] Huh! Really? Cornell university scientists don’t know what a farm child picks up during one farming season? The article is full of red flags for clickbait lies.
- oneoff786 5y agoI don’t understand how sexing birds isn’t a solved ML problem
- yunohn 5y agoSuper interesting story, I liked reading the exploration. > Today, he admits that perhaps the reason he hadn’t considered looking at the female side of things was a result of his own male bias. Honestly, the male scientists really disappointed me. Do they not have any curiosity or sense of professionalism? This guy dissected multiple penises and never once thought to dissect a vagina? Wow, just, wow.
- hnlmorg 5y agoIt's pretty easy to say that in hindsight but these people have a finite amount of research time and budget. Plus also mentioned in the article is that they actually had looked at vaginas before but dissected it in an incomplete way which lead to prior assumptions appearing valid when in fact they were not.
- bell-cot 5y agoAlternate hypothesis: Scientists, even male ones, are social creatures. It is possible that a fair number of male scientists did think to dissect a vagina "back in the day". But then reconsidered - for reasons varying from "quiet concern that such scientific interests could be misinterpreted by polite society" to "feedback from peers was notably less enthusiastic on that subject" to "research funding and acceptance of papers for publication proved more difficult". The two sentences immediately after your quote can be read this way: > ...a result of his own male bias. “It was fitting that a woman followed this up,” he says. “We didn’t need a man to do it.”
- supergirl 5y agohow scientific are this kind of explanations? “today we know that X% of duck sex is forced; that could explain why ducks have genitalia like they do”. the genitalia evolved over 10s or even 100s of thousands of years along with many other traits in ducks. we probably don’t know if ducks were so aggressive 200 years ago but we assume what we see today was the same 100k years ago?
- h2odragon 5y agoLooking at these structures dead and detached cannot show what agile, active organs they are in life. Study that and you have the last sexual kink that is still frowned on.
- ben_w 5y agoPeople describe a lot of very different taboos as “the last that is still frowned on”. I am rather more troubled by the idea of someone “enjoying” these dead examples in that way. But I have the same trouble with leather fetishism for exactly the same reasons, and most do not share my negative reaction to the latter. I wonder how that works, and why? Stream of consciousness here, but specifically about leather: could it be that the uncanny valley effect happens when the visual processing in our brains detect most of the signals to positively recognise an object, but missing a certain number of core features or possessing anti-features, and that my brain is trying to match again an unusual set of features such that leather induces this reaction in me — i.e. that it’s a person wearing someone else’s skin — whereas more normal people learned a substantially different set of feature detectors and just see leather as nothing more than a durable fabric?
- fortran77 5y agoI think she has more research to do: > That’s when she began thinking about conflict. Duck sex, she knew, could be notoriously violent. Ducks tended to mate for at least a season. However, extra males lurked in the wings, ready to harass and mount any paired female they could get their hands on. I never knew ducks had hands! I thought that was only in cartoons! This is big news, even bigger than reverse-threaded vaginas.
- DonHopkins 5y agoMale Barnacles are pretty wild and crazy guys, with penises eight times their body length, and their sweet romantic spermcasting! But those female Sacculina Carcini sure know how to keep their male mates in their place. https://en.wikipedia.org/wiki/Barnacle#Sexual_reproduction https://en.wikipedia.org/wiki/Barnacle#Sexual_reproduction >Sexual reproduction >Most barnacles are hermaphroditic, although a few species are gonochoric or androdioecious. The ovaries are located in the base or stalk, and may extend into the mantle, while the testes are towards the back of the head, often extending into the thorax. Typically, recently moulted hermaphroditic individuals are receptive as females. Self-fertilization, although theoretically possible, has been experimentally shown to be rare in barnacles. >The sessile lifestyle of barnacles makes sexual reproduction difficult, as the organisms cannot leave their shells to mate. To facilitate genetic transfer between isolated individuals, barnacles have extraordinarily long penises . Barnacles probably have the largest penis to body size ratio of the animal kingdom, up to eight times their body length. >Barnacles can also reproduce through a method called spermcasting, in which the male barnacle releases his sperm into the water and females pick it up and fertilise their eggs. >The Rhizocephala superorder used to be considered hermaphroditic, but it turned out that its males inject themselves into the female's body, degrading to the condition of nothing more than sperm-producing cells. https://en.wikipedia.org/wiki/Rhizocephala#Description_and_lifecycle https://en.wikipedia.org/wiki/Rhizocephala#Description_and_l... >Description and lifecycle >Sacculina carcini (adult female) parasiting a crab (Carcinus maenas). Haeckel's drawing also shows the internal network of filaments from the parasite. >As adults they lack appendages, segmentation, and all internal organs except gonads, a few muscles, and the remains of the nervous system. Females also have a cuticle, which is never shed. Other than the minute larval stages, there is nothing identifying them as crustaceans or even arthropods in general. The only distinguishable portion of a rhizocephalan body is the externa; the reproductive portion of adult females. >Nauplii released from adult females swim in water for several days without taking food (the larva has no mouth and no intestine) and transform into cypris larvae (cyprids) after several moults. Like the nauplii, the cyprids are lecithotrophic (non-feeding). The female cypris in Kentrogonida settles on a host and metamorphoses into a specialized juvenile form called a kentrogon, which has no visible segmentation and has no appendages except the antennules that are used to attach itself to the host, and whose only purpose is to inject a cell mass named the vermigon into the host's hemolymph through a retractive hollow stylet on its head. The kentrogon stage seems to have been lost in all of the Akentrogonida, where the cypris injects the vermigon through one of its antennules. The vermigon grows into root-like threads through the host's tissue, centering on the digestive system and especially the hepatopancreas, and absorb nutrients from the hemolymph. This network of threads is called the interna. The female then grows a sac-like externa, which consists of a mantle, a mantle cavity, an ovary and a pair of passageways known as cell receptacles, extruding from the abdomen of the host. >In the order Kentrogonida, the virgin externa contains no openings at first. But it soon molts to a second stage that contains an orifice known as the mantle departure, and which leads into the two receptacle passageways — once assumed to be the testes in hermaphroditic parasites before the realization that they were actually two separate sexes — and starts releasing pheromones to attract male cyprids. From inside the body of the male cypris that succeeds in entering the departure, a unique and very short lived male stage called the trichogen emerges through the antennule opening. It is the homologue of the female kentrogon, but is reduced to an amoeboid unsegmented cuticle-covered mass of cells consisting of three to four cell-types: the dorsolateral, the ventral epidermis, the inclusion cells, and the postganglion. The externa have room for two males, one for each of the receptacles, which increase the heterozygosity of the offspring. Once inside, the trichogen will shed its cuticle before reaching the end of the passageway. >In the order Akentrogonida, which form a monophyletic group nested within the paraphyletic Kentrogonida, the male does not develop into a trichogon, and the cypris injects its cell mass through its antennule and directly into the body of the immature externa. The offspring also hatch directly into fully developed cyprids instead of nauplius larvae (except for a few species of kentrogonid rhizocephalans, which hatch into cyprids like the akentrogonids, the kentrogonids have kept their nauplius stage). In species like Clistosaccus paguri, the male injects its cluster of cells which migrates through the connective tissue of the mantle and into the receptacle. But in forms like Sylon hippolytes the receptacle is absent, and the males cells implant in the ovary instead. While only a single male can settle in each receptacle, which is the rule in Kentrogonida, the number of implanted males in Akentrogonida can range from just one to more than ten. >The small cluster of cells injected by the male cypris will, once it reaches its destination inside the female, differentiate into a loosely connected mass of sperm-producing germ cells. Being nothing more but sperm-forming cells, these adult male rhizocephalans represents the simplest form of male in the entire animal kingdom. Mature female externa releases eggs into its mantle cavity where eggs are fertilised by sperm from the hyper-parasitic male(s). Due to the larval sexual dimorphism in the Kentrogonida, the females produce two different egg sizes; small female eggs and larger male eggs. It appears the sex determination in Akentrogonida is environmental. >In Peltogasterella gracilis, the externa produces several batches of larvae before it drops off the host, taking the male(s) inside with it. After the original externa disappear, the host moults and the interna grows buds that each develops into a new virgin externa. The females commonly has two cypris cell receptacles. With more than one externa, and new ones replacing the old ones, each female Peltogasterella can receive sperm from numerous males during its lifetime. >The externa is where the host's egg sac would be, and the host's behaviour is chemically altered: it is castrated and does not moult until aged externa(e) drop(s) off. The host treats the externa as if it were its own egg sac. This behaviour even extends to male hosts, which would never have carried eggs, but care for the externa in the same way as females.
- bannedbybros 5y ago
- frankus 5y agoCould the opposite spiral directions be just roughly the same structure but one is turned inside out? I’m not up to speed on topology but generally turning things inside out changes the “handedness” (cf. a glove).
- frankus 5y agoMaybe "turned inside out" isn't getting the right idea across, since the "inside" of an orifice is still a continuation of the outside surface of the organism. Instead picture one of those cabinets with the built-in gloves that are used for sandblasting or handing hazardous materials, and focus on the glove on the right side. Normally a person's right hand would fit inside the glove (which as before is just a continuation of the outside surface of the cabinet). Now pressurize the cabinet so that the glove pops out and inflates. The glove would now be in the shape of a left hand, and if you were to try and put a right-handed glove on it, it wouldn't fit. There isn't really a profound takeaway here, other than maybe they're crediting a a genital arms race for something that is just an accident of related reproductive organs (there's a long list of these types of structures: https://en.wikipedia.org/wiki/List_of_related_male_and_female_reproductive_organs https://en.wikipedia.org/wiki/List_of_related_male_and_femal...).
- WaitWaitWha 5y ago"No one seemed to have an answer." "..they both did a double-take. He had never seen anything like it. " and, so on... Interesting she did not ask the farmers where she purchased the ducks to get their insight...
- staticassertion 5y agoDo farmers investigate the inner workings of duck vaginas?
- WaitWaitWha 5y agoI did not make myself clear. Farmers have real-world observations, including duck parts. It never hurts for a scientist to hear external information that may be relevant, right or wrong.
- staticassertion 5y agoYeah, reasonable.
- notaduck 5y ago"Today, we know that genitalia do far more than just fit together mechanically. They can also signal, symbolize and titillate—not just to a potential mate, but to other members of a group. In humans, dolphins and beyond, sexual behavior can be used to strengthen friendships and alliances, make gestures of dominance and submission, and as part of social negotiations like reconciliation and peacemaking, points out evolutionary biologist Joan Roughgarden, author of the 2004 book Evolution’s Rainbow: Diversity, Gender, and Sexuality in Nature and People." What are we to infer about cultures that forcibly remove erogenous tissue (clitoris/clitoral hood/vulva on females and foreskin/frenulum/ridged band on males) from their children?
- globular-toast 5y agoI think maybe the "wild" thing isn't appropriate in an article that's actually about animals.
- JoeAltmaier 5y agoIt may help to consider that, while an egg is a chicken's way of making another chicken, equally valid you may view that a chicken is an egg's way of making another egg. Follow this train of thought, we can imagine that reproductive morphology is there for it's own sake. The genes that create it, are successful if they create creatures that propagate those genes. Never mind how onerous it is to the creature. Sure, they can't cause the creature to actually expire in the effort. But short of that, they can get as strange as galapagos birds and so on, purely for their own sake.
- Jenda_ 5y agoOh, finally, a SMBC mystery thoroughly explained! (https://www.smbc-comics.com/comic/pokemon https://www.smbc-comics.com/comic/pokemon)