This is my account of some of the issues raised in last Thursday's
lecture. I hope I have got the right end of the stick.
Due to the fact that eggs are much larger than sperm and so require
more energy for production and movement etc, fewer eggs are produced
than sperm, and are produced at higher cost to the female. Sperm
however, are produced in larger amounts because they require less
energy for production etc. Females have more control over the
development of the offspring (they always know who the mother is)
whereas males need to produce more sperm (and inseminate more females)
inhance their reproductive success. Females will select males on
commitment to her, on general fitness, and attractivess. (This will
make her sons more attractive and give her more grandchidren). Females
hide ovulation to have the chance to mate with more males and have the
choice of the best (fittest) sperm by making the sperm themselves fight
it out (Sperm wars). Females, due to the fact that they are investing
more in the offspring in terms of energy, will "cheat" in this way and
ensure the fittest father for their child.
The book claims that this is the basis for all human sexual behaviour,
and that it is mainly driven by unconcious desires. This unconcious
question is important as it will explain some otherwise "unreasonable"
behaviour such as adultery. As before, the genes of each partner are
basically "selfish" and are using behaviour to enhance the best chance
of survival. Females by using the fittest sperm and males by
inseminating as many women as possible.
A male with a stable partner will keep her "topped up" with sperm
(routine sex) to ensure that his sperm will be in the best postiton
to fertilise the egg and to win any sperm wars. At the same time he
will be driven to inseminate other women to have other chances of
wining a sperm war should his partner be unfaithful. Males also have
"family planning" strategies by using different types of sperm.
"Egg-getters" are the rarest and are intended to fertilise. "Killers"
and "blockers" are intended for sperm wars. A male will use cues
both external and subconcious to try and determine whether a woman
has been unfaithful and if he needs to fight sperm wars.
(Question: Does a man, at the time of sex, suddenly, after foreplay,
change the type of sperm he will be using???????)
Also, why is new sperm best? (Apart from the obvious reason that sperm
will be younger and less will be dead) Does young ejaculate contain
more of one type of sperm??
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