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Science

Human Males Evolve At a Faster Pace Than Females 454

Posted by CmdrTaco
from the can't-say-i'm-surprised dept.
Tisha_AH writes "A report by the Whitehead Institute indicates that the human Y chromosome present in males is evolving at a furious pace. Across the chromosome there can be as much as a 33% difference within humans alone. The portions of the chromosome evolving fastest are related to sperm production."
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Human Males Evolve At a Faster Pace Than Females

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  • by cabjf (710106) on Thursday January 14, 2010 @10:27AM (#30763676)
    I wonder if this would counter the other studies saying that the y chromosome is doomed.
  • by dvoecks (1000574) on Thursday January 14, 2010 @10:31AM (#30763730)
    "Darwin Award" winners are pretty overwhelmingly male.
  • Re:At last... (Score:2, Interesting)

    by Darth Sdlavrot (1614139) on Thursday January 14, 2010 @10:38AM (#30763814)

    She might not be too far wrong though.

    A slightly acidic environment is likely to kill more Y sperm, which aren't as tolerant as X sperm.

    I can't cite any studies to support this, but have a friend whose OB/GYN told her that as a result of her body chemistry she was unlikely to conceive any boys. (She did manage to beat the odds though and had a boy, and three girls.)

  • interesting factoid: (Score:5, Interesting)

    by circletimessquare (444983) <circletimessquare&gmail,com> on Thursday January 14, 2010 @10:50AM (#30763992) Homepage Journal

    testicle size in simians is correlated with female permissiveness. such that, in chimpanzees, where a female in estrus is pretty much a gangbang, chimpanzees males have evolved humongous testicles. they need to, because in such a situation, the only strategy available to the male to ensure his genetic continuance is to simply overwhelm other male's sperm with sheer ejaculate volume

    meanwhile, in highly monogamous simians who mate for life, such as gibbons, the testicles are tiny. there's simply no need for so much ejaculate volume, its a waste of resources. she's not going anywhere

    interestingly enough, human males have intermediate sized testicles, owing to the fact that human females are semi-monogamous/ semi-polygamous

    however, i've always wondered why testicles appeared on the outside of the male mammalian body. it seems a ridiculous vulnerability and i've never heard a good explanation as to why. for example, dolphins aren't swimming around with their balls out: the need to be streamlined. of course sperm need a lower temperature to develop, but thats an effect, not a cause. i'm saying wouldn't it be better to have your testicles inside your body and evolve sperm that develop at a higher temperature? its pretty ridiculous to have such an important organ dangling outside unprotected. i never understood why

  • by Anonymous Coward on Thursday January 14, 2010 @11:15AM (#30764364)

    You know the womens groups will come out that this is sexist? I swear it's like the religious groups who come out with their nonsense when science disproves one of their "theories" - you know like the earth is not flat, does not reside in the center of the universe, and is not approximately 6000 years old.

    Perhaps if you didn't flamebait them at every opportunity that arose? I swear every damn article that talks about evolution has DOZENS of agnostic drones bitching about 'religious groups'. Wtf really... Is it really that bad someone doesn't believe what you do? They are not part of the borg so you call them out at every opportunity? Perhaps you act as bad as you accuse others of doing? Is this how you want to present yourself to others? Sounds like you (and your parents) also missed the point of being called to the principals office. You like to piss people off (btw that is not a good thing). Not what the article was about... So far my sample of 2 examples from your rant shows this about you.

    But my little rant will not change your mind. You will just blunder on thru life wondering why everyone around you is an 'idiot'. Perhaps you need to reflect on what *YOUR* actions do to others.

    Sorry to rant on you but the 6000 number is getting old. I would be willing to bet cold hard cash 99.9% of 'religious groups' do not even believe that number. You are generalizing what a fairly small group calculated out of the bible and what meme you heard on the internet about 'religious groups'.

    Perhaps if you attended some 'religious groups' meetings you might get something from it instead of hatred (which is all I have seen from you so far). Here is what I have gotten out of it. You get out of life what you put into it. In life you make good choices and bad choices all the time. Ignore hatred it is self destructive and not helpful in life.

    Are their loony jobs out there? Yes, they tend to exist in all groups. Just ask someone who collects every star wars memorabilia that exists. While the rest of us played with the toys a bit and then let it go. To give you an example my gf. Her first encounter with star trek was a dude who built his own klingon costumes. What sort of impression does that give to her? She will not watch star trek. She will not even give it a chance. Oh and I call her out on this too so you are not alone. Perhaps you do the same with other things in your life?

  • by smooth wombat (796938) on Thursday January 14, 2010 @11:17AM (#30764414) Homepage Journal
    Males are not an independent population. And individuals don't evolve, so the notion of evolving males is silly.

    You might want to look at the hummingbirds of St. Lucia before you make such a broad statement. The male bills are much shorter and straighter than those of the female which are longer and more curved. Same species, different bills. For reference [georgefox.edu]. Also, the video [pbs.org] from the PBS show where this was discussed.

    Also, why can't an individual evolve? How do you think evolution works? That everyone in the group changes at once?
  • by Anonymous Coward on Thursday January 14, 2010 @11:20AM (#30764468)

    Male-only sexual selection has been seen before. I can't remember the species, but its sperm has become cooperative, not swimming solo like your regular sperm, but hooking up in huge clusters, so they can swim faster than the sperm of the competition. Although that case was related to promiscuity, you could theoretically even get effects like this in monogamous species, although at a far lower pace. Suppose a mutation in one sperm stem-cell makes its y-chromosomes contain some useful trait. Then its offspring might stand a better chance beating other sperm from the same individual even.

  • just like fruit flys (Score:3, Interesting)

    by cinnamon colbert (732724) on Thursday January 14, 2010 @11:25AM (#30764580) Journal

    Many years ago, I read a serious genetics paper about this. The scientist managed to setup up a colony of fruit flys (drosophilia melanogaster) so that the females remained static - they did not evolve - and the males did.
    In fruit flys, multiple males mate with a female, so there is a lot of competition between the different sperm.
    What happened is that the males evolved their ejaculate to become more aggressive, to outcompete the other males; in some cases, the ejaculate became toxic to the females.

  • by mindbrane (1548037) on Thursday January 14, 2010 @11:27AM (#30764614) Journal
    1st off i'm not going to cite stuff because i've not got it at hand and any citations would be from audio files. the recent courses i've listened to in biology and, more specifically, evolutionary biology suggest the y chromosome is a shrivelled up little thing fast loosing genes. as a guy i didn't much like hearing that either. there's some evidence in some flatworm species that 'penis fencing' suggests bearing young is an "aggressive act" foisted upon a weaker rival. how that would scale up to other species i couldn't say. there are recent findings that male sperm have complex mechanisms that try to induce the egg to draw down from the female as much developmental resources as possible while the egg has similar mechanisms that will try to limited the amount of resources a fertilised egg can demand of the mother. this seems to suggest that there's not only great complexity in development but that sperm and egg are in competition. it's very complex not yet nearly understood stuff. also a 'faster' rate of evolution isn't necessarily a sign of good things to come or an evolutionary edge. what i term differential evolution, for want of a better term, seems not to have been studied or made available to mere lay people such as myself. by differential evolution i mean what does it mean when a species evolves faster. does it simply mean the species has greater fitness? what are the consequences of 'faster' evolution and can such consequences be considered in anything but out of context, almost trivial generalities?
  • by Scrameustache (459504) on Thursday January 14, 2010 @11:36AM (#30764796) Homepage Journal

    The notion of evolving males is not silly. That's why peacocks have big bright displays, while peahens are boring brown.

    That boring brown is camouflage. If a predator comes along, the bright, loud male can be chased away from the camouflaged female covering the eggs.

  • by TheRaven64 (641858) on Thursday January 14, 2010 @11:39AM (#30764846) Journal

    Mod parent down. The point he made is entirely wrong.

    According to the grandparent's hypothesis, genes would mutate more frequently in men than in women. Genes that are shred between the genders would mutate more in men than women, but in each child a mixture of the more-mutated and less-mutated genes would be provided by the two parents and so they would average out. The genes only present in the male (i.e. on the Y chromosome) would not have this averaging effect and so would contain a higher total level of mutation. X chromosomes inherited from the male parent in women would be more likely to be mutated than the ones inherited from the mother. Y chromosomes do not appear in females, so they would only come from the father and would be subject to a greater amount of potential mutation. Multiply this by a few thousand generations, and you'd see a greater level of mutation in the Y chromosome than in the rest of the genome which is exactly what TFA says is seen

    The grandparent produced a hypothesis that supported the observation. The next step according to the scientific method is to design a test that would contradict the grandparent's hypothesis but not the observed evidence. Not simply to say 'mod parent down'.

  • Re:The cynical... (Score:3, Interesting)

    by GooberToo (74388) on Thursday January 14, 2010 @11:40AM (#30764882)

    Plastic surgery has drastically reduced selective pressures on women. In fact, I remember hearing one geneticist say once such methods become globally accepted, the rate of human evolution is likely to drastically slow, if not come to a stop.

  • by R2.0 (532027) on Thursday January 14, 2010 @11:41AM (#30764886)

    I think you may have the cause and effect wrong. I think sperm can't survive long at body temperature specifically BECAUSE a woman's eggs are so far inside her. The sperm's lifetime is drastically shortened by the conditions inside a uterus. This is good because, if sperm were long lived, parentage of offspring would always be in doubt - Is the daddy the guy she screwed yesterday or a month ago? This way, the odds are far more likely that the last one in is the Daddy.

    I think sperm temperature range is the CAUSE of testicles, not the effect.

  • Re:Er... (Score:4, Interesting)

    by tmosley (996283) on Thursday January 14, 2010 @11:49AM (#30765062)
    I see you've been reading h-manga again.
  • by Maxo-Texas (864189) on Thursday January 14, 2010 @01:26PM (#30766834)

    You may not already be aware but it is slightly addictive. The chemicals and hormones in it improve female happiness and mood.

    These question is
    1) is it pushed from the male ( those who have a chemical that makes the female happier have more kids)
    2) or pulled from the female (those females who are naturally happy because of innocent chemicals have more kids)

  • by Anonymous Coward on Thursday January 14, 2010 @02:59PM (#30768626)

    But the parents point is still correct, since many male expressed traits may be located on autosomal genes.

    For instance, the gene which produces testosterone is not located on the Y-chromosome, even though testosterone is commonly thought high levels of testosterone expression are responsible for many of the secondary sexual characteristics of males.

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