Life History Parameter: Sex ratio/Age of First Reproduction

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    • #1092
      sole_05
      Participant

      Some interesting issues that needs some input to clarify some of these evolutionary changes in human sex ratio and age of first reproduction. Here we go!

      1. There is common concept that males in some human professions (e.g. deep sea divers, footballers) are more likely to father daughters than sons. Just wondering if there is an evolutionary explanation for why particular males may be more likely to have daughters? Can you think of a mechanism explanation of how this might happen?

      2. Even for the earliest maturing species of animals and plants there is always a development phase before individuals are fully mature and able to reproduce. But why is it so rare for species to be born with fully reproductive organs ready to go?

      3. Back to humans. Another common concept is that the age of maturity in humans has been declining over recent centuries. ie. humans are capable of reproducing at an earlier age now than they could three or four hundreds years ago. Any explanation on this, and what role of evolution in this change?

      Would appreciate any thoughtful comments.
      sole

    • #23902
      James
      Participant

      Wouldn’t really be benficial to be able to reproduce immediately. The population would surely become overcrowded; the body wouldn’t be prepared to give birth; the likelyhood of survival for offspring is low enough without having to mate and give birth etc etc

      Physical evolution over a few hunded years is not the answer, it’s more likely a social and behavioural change.

    • #23909
      MrMistery
      Participant

      1. This is wrong. The probability is 50-50, the profession of the father has nothing to do with it. Think of it like this: a football player has a boy, he teaches his son footbal, happy family, end of story. He has a daughter, he will complain to everybody that he has a daughter. So, it is more likely that you hear about him having a daughter than a son–> that popular belief

      2. This differs for r and k organisms. R organisms usually are closer to that situation than k organisms.

      3. Like it was said, it is a matter of behaiviour. In USA, one out of 10 children has sex before the age of 13(i was stunned when i heard this!). Though I, as a 13 year-old, could have sex at this age 300 years ago, i was not permitted to. Since now we live in a more liberal society, girls, watch out! 😉

    • #23910
      Poison
      Participant

      sex is an instinct. You can not stop it… 😉

    • #23912
      MrMistery
      Participant

      Yeah, but sometimes we need to control our instincts. Fortunately, only sometimes 😀
      By the way i am not 13. Am i am 16 and a half 😀

    • #23923
      mith
      Participant

      1.Football players might get hit in the nuts more than people in other professions. I dunno how that might affect sperm count though 😉

      2.Probably requires too much energy. The parent would need to contribute extra energy to support the child and allow it to mature sexually, and the child would expend extra energy to keep the sexual organs functional. I’d think that the first priority is not sex, but survival.

      3.Not sure about this. Wasn’t Juliet 13 and Romeo 15?

    • #23948
      MrMistery
      Participant

      Hello… That wasn’t for real!! Shakespeare imagined it 😀 Anyway, it was simply an opinion
      PS: you are probably right on the second one

    • #23986
      Poison
      Participant

      At the age of 13 you can have sexual desire. Especially if u are a girl. And you know, the age of teenage can change.

    • #24086
      MrMistery
      Participant

      I saw a boy on a talk-show who began his sexual life at the age of 9. That is twisted

    • #24132
      Poison
      Participant

      9? with whom? I don’t think it is normal, Actually, I’m sure that it isn’t normal. 🙂

    • #24154
      MrMistery
      Participant

      With a 12 year-old girl who had done it before and taught him

    • #24177
      har0bed1813
      Participant

      that’s really sick… Half my friends are stil virgins, and they are mostly 16-20!
      and I think it’s not just evolution, but mostly upbringing and culture.

    • #24203
      Poison
      Participant
      quote MrMistery:

      With a 12 year-old girl who had done it before and taught him

      teaching sex. 😀 sounds strange. I cannot imagine what the girl (actually the girl is youg too.) said to him.maybe she said: “I will give you some lollipops, if you do that.” 😛
      And it is also strange that, a child at the age of 9 is sexually active!!! I felt myself very old. Hey guys, maybe it’s too late for us to have sex. 😆 Be careful, we might have an heart attack. 😛

      quote har0bed1813:

      Half my friends are stil virgins, and they are mostly 16-20!
      and I think it’s not just evolution, but mostly upbringing and culture.

      I agree. I know some people who are virgin, and their age is over 20. Being a virgin or not is just a choice. And of course culture plays an important role too.

    • #24234
      MrMistery
      Participant

      An american pshycologist said that man acts on 3 principles:
      1. pleasure principle- you do what you like
      2. denying non-pleasure principle- you don’t do what you don’t like
      3. heard principle- you do what others do
      So if everybody around you is having sex you will also be tempted to do it. But being a virgin at the age of 20 is not a bad thing. If you ask me, waiting until the wedding night is a little romantic, although i do not intend to do it 😆 😆
      By the way, Ozge, it’s “have sex”, not “make sex”. I am not obsessed with grammar but that something you should know 😉 General knlowledge 😉

    • #24271
      b_d_41501
      Participant

      Have Sex. Make Love.

    • #24351
      Poison
      Participant
      quote MrMistery:

      By the way, Ozge, it’s “have sex”, not “make sex”. I am not obsessed with grammar but that something you should know 😉 General knlowledge 😉

      Thank you my grammer teachers. I edited it.. 🙂

    • #24455
      2810712
      Participant

      for the time being i need to control my disers to make jokes on the background of this thread… 😥 and have to try to answer those qs asked . ❗
      💡 If we get ans. of !st one , it will explain or help explain the effect of soma on germa , which may help to establish some more concepts in NEO-LAMARKISM…
      So, we need to think guys…

      hruusheekeish

    • #30881
      Antonythe
      Participant

      The reason that fathers of a certain profession like divers and footballers father more daughters is because of the lowered testoserone level they have.

    • #30905
      mith
      Participant

      Where are you referencing from?

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