Having late night, half imbibed conversations around our kithen table with my brother and sister and trying to figure out why males evolved to have facial hair and women didn't? Any answers theadvancedapes?
My brother hypothesizes that the higher the estrogen levels the more fertile the woman would have been and therefore it was selected as such. Right or wrong?
Your brother is not necessarily wrong - there is a hormonal basis for the lack of female facial hair. The real evolutionary cause is facial neoteny. Neoteny is the "retention by adults of traits previously seen only in juveniles". The effects of neoteny are massively exaggerated in human females (i.e., larger eyes, smaller noses, and fuller lips). Many physical anthropologists have shown that you can estimate the age of an individual based on information about eye width, nose height, and lip height alone - and it is clear that women (on average) have much larger eyes, smaller noses, and "taller" lips than do men. In this sense, facial hair growth can be seen as part of this neotenous package (as infants and children also do not have facial hair - obviously). This could be adaptive, or perhaps an exaptive - no research has really tested which it is (but the actual selective pressure was very high since lack of facial hair is always seen as a sign of physical attractiveness cross culturally). I would add that several studies have shown that in the neotenous package - women are always rated as more sexually attractive cross culturally if they exhibit "supernormal" aspects of the neotenous package, and studies of high end fashion magazine and super model magazine model facial proportions also end up falling on the most neotenous end of the facial spectrum. I would add that in these studies the researchers admit that it is hard to control for what it was - evolutionarily speaking - that men selected for in women - neotenous faces, or maximal waist-to-hip ratio - both of which are indicators of youth and high fertility. To end - I took a sexual selection theory course in grad school. Two of the most interesting questions to me where the following: A) Why are humans the only species that have hair that needs to be cut? B) What is the evolutionary origin of the female orgasm? One of these questions is currently still a mystery. What one do you think it is?
The female orgasm incentivizes sex. Why do humans have hair that needs to be cut? Beats the hell out of me.
Humans have to cut their hair because it is an amazing indicator that you are not currently struggling with problems most intimately related to natural selection (base level survival). No matter the culture, people style their hair. It can be any style. It will vary by culture. But all cultures have very advanced styling methods for hair. If you don't style your hair -- you are seen as someone that can't take care of him or herself (i.e., "homeless" "starving"). So there was high sexual selection for people that styled (and hence "cut") there hair in some way.Why do humans have hair that needs to be cut?
b_b is right - we don't know whether Homo neanderthalensis styled their hair - and we don't know with a high degree of certainty when modern humans started styling their hair. My best guess is that humans would have been caring about hair style since the emergence of the genus Homo 2 million years ago. My rationale for this is that grooming is a fundamental aspect of social primate behaviour. All primates play with each other's hair in non-random ways. The best hypothesis for the emergence of language suggests that it evolved as some type of social vocal grooming practice, not dissimilar from that of gelada baboon communication. In this type of world styling each others hair would have been an important symbol for health and status (OH, she is styling your hair?! Lucky! Or "your hair looks good today - you must have a lot of close friends!"). At the very least - the strong adaptive function of a hair style cross-culturally suggests that our ancestors were not unkempt brutes. All hunter gatherer modern humans place high value on style and artistic expression with body art and various hair styles. Our ancestors in pre-history likely did the same for a very long time.
Fascinating stuff! Though I am partial to women with nice hair, it kind of sucks that it seems we may be selecting against female orgasm. It seems a lot harder to select for female orgasm though, since it's not exactly on display. Not to mention that culture and individual women (and their openness in regard to their own sexuality and willingness to experiment with technique) often require quite a lot before agreeing to allow one to see how capable they are of achieving it.
I don't really believe that the female orgasm will be "selected away". Selection pressures take thousands of years to really take effect, especially one as subtle as that, and I can't see the modern pressure for it or how it would actually affect reproductive success. Also, obviously I believe we are going to be evolving technologically over the next 100 years in profound ways - and that it is more likely that biological sex altogether will be gone before the end of this century. Hrdy might have had a point if we had stayed hunting and gathering for thousands of years into the future.
By biological sex, am I to understand that you mean sex for procreation or the physical act itself? Messy as it is, it seems like losing sex would be a shame. Learning about a person through their particular physique and physicality is such a human and humanizing experience.
I feel as though the technocultural process will eventually completely model and overtake the biochemical process. So by the death of biological sex I mean the actual death of sharing gametes, period. Humans at the moment are caught between two worlds - the biochemical world and the technocultural world. We have been cyborgs since our birth as a species. But if there is one undeniable trend - it has been towards creation of a world with more and more technoculture. In fact, it is the technoculture that we view as uniquely human. Everything that is biochemical is what we share with animals. At the end of this century I think sex will just be sharing brain patterns with an infinite combination of other minds. The path to this type of sex has already started (and is accelerating). Biological sex won't be dead in the Global Brain - but it will be dead a few decades into the Global Brain (IMO).
I see what you mean by technoculture being viewed as more human and the biochemical being seen as animalistic. If I'm being honest, I have always thought that people who deny their animal natures as somewhat neutered and lacking in vitality. As exciting as high technology is, I suspect that it will be difficult to eradicate the animal from the human. I understand that this is not necessarily an overt goal, but I find it weird that people are uncomfortable with being animals, since it's something I happen to enjoy.
If technology really results in a variety of choices in regard to body augmentation then it will be interesting to see how people choose to use it. For sex to leave the animal world, it will have to satisfy better in a majority of ways. I can't imagine how though, since my experiences are all of course, biological. But even in the biological, the mind is important, that can't be denied.
I certainly don't deny my "animal natures". I just feel like we are in the process of modelling biochemistry - and then we will redesign our biochemistry, and then we will ultimately replace our biochemistry completely with technoculture. I'm just starting to feel like we can actually quantify this transition and perhaps extrapolate to understand roughly the decade within which the transition will occur. I feel like once we can share our thoughts directly (post-language) this will open up massively powerful sensual experiences that biological sex can't match. Also, once we live indefinitely reproductive will have lost its function. I know there are a lot of assumptions in this perspective - but I feel like the trends are strong and should reach full maturity given my perspective on the global brain's capabilities. I basically think collective mindspheres were replace biological sex. Of course, people will use collective mind spheres in different ways - but they will all be fundamentally technocultural bases - not biochemical bases - and will not involve the sharing of gametes.
I didn't mean you specifically, sorry if that was unclear! I'm sure you've seen the kind of people I'm talking about though. I meant the kind of people that refuse to accept that the neat, clean styrofoam packs of water plumped chicken breast, has anything to do with the clucking, pecking and shitting thing that a chicken is. This possible transition though, from a physical-mental state into a purely mental state-- how would the senses transition? I guess that's part of what I'm trying to better understand. So, in thought only interactions, then how will social cues change? Surely, there would be need for people who are only familiar with physical social cues would have a problem when there is no facial expression to see, or body language to read. To extend this, sex is now generally initiated and agreed upon through the subtleties of these physical expressions in addition to the subtleties of verbal communication. I have rarely said to a woman, "let's have sex" and had her agree. Most often, the response is either, "no" or some version of, "no! we need to do the dance!" I don't know enough about the trends to refute you and it does seem that at the very least, the possibility of what you are saying is already in the public consciousness to some degree, if only because there have been so many science fiction scenarios where intelligent beings have somehow transcended their bodies. It is interesting though, that those that have transcended their bodies tend to be bad guys.I certainly don't deny my "animal natures".
Mental states are physical states. They have a physical basis. We will still have bodies. They will just not be biochemical in nature (IMO). Yes, there is an evolved sexual mating pattern. This will completely be wiped away and replaced with memetic information transfer (instead of genetic information transfer) - "sex" will be completely idea sex and it will have different contexts for who wants to have idea sex with who (just as happens today). Yes, all Hollywood science fiction and most other science fiction portray anyone who has fundamentally altered their "human-ness" to be "bad". It is a disappointing aspect of science fiction, but not all science fiction is guilty of this. There will come a point in time when transhumanism will not be demonized or constantly woven into fear-mongering narrative structures.from a physical-mental state into a purely mental state
I have rarely said to a woman, "let's have sex" and had her agree. Most often, the response is either, "no" or some version of, "no! we need to do the dance!"
It is interesting though, that those that have transcended their bodies tend to be bad guys.
Wow. That's fascinating. So you're saying that the question shrouded in mystery is the issue of the female orgasm? Go on, if you don't mind..
It is the most complex mystery I have encountered in evolution. I'll quote from Bateman & Bennett. 2006. The biology of human sexuality: evolution, ecology, and physiology. Physiologically, it has been suggested that the orgasm may have a very clear adaptive function in that it stimulates the mouth of the cervix to dip into an ejaculate deposited in the vagina, aiding uptake and hence likelihood of fertilisation. Against this argument is that for this to happen the female orgasm has to occur after the male orgasm (unless the cervical movements continue after the orgasm) and most women (Western, Caucasian) report that their orgasms usually occur before that of their partner. Depressingly, the primatologist Sarah Blaffer Hrdy (1999) has pointed out that, even, if orgasms do function to “dispel tension and strengthen bonds between partners”, for the vast majority of women in much of the world, living in aggressively patriarchal societies, orgasms, reflecting libido and sexual assertiveness are more likely to get a woman punished, beaten or killed. Many societies have customs such as veiling, purdah, and, worst of all, genital mutilation through clitoridectomy (total or partial excision of the clitoris) and infibulation (sewing together of the vaginal lips). If there is any kind of selection in action here, Hrdy suggests that the female orgasm may once have been an adaptation, but now is no longer selected for, and will disappear.The female orgasm, with no ejaculation, is more difficult to explain. Female orgasm is not limited to Homo sapiens; certainly, chimpanzees experience it. The most parsimonious explanation for female orgasm is that, just as the clitoris is a homologue of the penile glans, so is the female orgasm a homologue of the necessary male orgasm: in other words it is merely an epiphenomenon, a side effect of parallel development of males and females. In support of this view, it is pointed out how rarely the female orgasm occurs from intercourse (a third of women in a British study reported never, or rarely, having an orgasm during intercourse). Another view is that, regardless of the male and female orgasm originally being ‘mere’ homologues, there can still be selection for satisfying, pleasurable female orgasms if they help to ensure a strong pair bond between sexual partners. In the pygmy chimpanzee, or bonobo (Pan paniscus), females will rub their clitorises together to climax. The bonobo clitoris is much larger than that of humans, and orgasms in this species do seem to act as social bonding device.
If I were a lady, I would be woo'ed knowing a smart a guy as yourself is working on the mystery of the female orgasm, the most complex mystery you've encountered ; ) May the female orgasm's mystery reveal itself to you one day.It is the most complex mystery I have encountered in evolution.
Haha, I haven't brought it up on a first date yet.
YES I LINKED THAT WIKIPEDIA PAGE DOWN THERE EXPERT STATUS EDIT: I also know from r/askscience that the orgasm question is ongoing. I think one hypothesis is that it makes women enjoy sex more, which leads to more reproduction. Makes sense to me on a surface level.Your brother is not necessarily wrong - there is a hormonal basis for the lack of female facial hair. The real evolutionary cause is facial neoteny.
Well, I just did quite a bit of reading and it seems to be, while not fully understood, probably more or less for the reason you would assume -- sexual attraction. Less hair is a sign of youth, which is a sign of potential fertility. There were some good paragraphs here.
r/askscience mostly let me down though.
It's just how male lions are gifted with a mane. It shows maturity and it's intimidating, not to mention hella cute.
I just wanted to take a minute and say thanks to theadvancedapes and flagamuffin for the answers given. It was pretty awesome to wake up the next morning and have some answers to our late-night drunken questions. TIL about neoteny
Well - this question is kind of redundant since - yes - everything has evolved! But I take it the meaning of this question is - does everything exhibited phenotypically have an adaptive basis. And the answer to that is almost certainly not. Things can be selected for because they come in packages randomly with other genes that are functional. If the selection pressure over time is strong enough for another trait - this trait gets carried along with it - even though it wasn't advantageous one way or the other. Also, mutations can of course occur and be phenotypically expressed. These mutations are not necessarily always advantageous either - but if they are a major deterrent to increased fitness they will usually be "weeded out" - given enough time. Phenotypic traits can also be exaptive - meaning that they evolved for a specific purpose - but now they serve a different purpose than the one they originally evolved for. A good example for this would be nails - which wouldn't have existed if we didn't evolve from ancestors who originally had claws. We didn't need claws so the exaptive relic is a hard keratin surface where claws used to be!
If I understand the question you are asking correctly, the answer is no if you buy this theory. I'm an armchair enthusiast for this sort of thing, still waiting on theadvancedapes for real answers. :p