How did men and women evolve different traits, exactly?

V

visceral_instinct

Monkey see, monkey denigrate
Valued Senior Member
Please excuse my lack of knowledge of genetics here...

So, how did we evolve so that male-typical traits - in general, anyway - pass on to males and female ones pass on to females?

Say you have Caveman X who has very good visual-spatial skills, and is more successful at hunting and providing for his children than other males, so he has more children and passes on his DNA to more individuals who also have good visual-spatial skills. His mate, Cavewoman X, has very good ability to single out small visual details, which is very useful for finding food, so she is also more fit than others of her gender.

Wouldn't their hypothetical offspring get both his visual-spatial skills and her ability to look for things in a high sensory environment, or some combination of both their traits, rather than the males inheriting one set and the females inheriting the other?

Please don't tear me to pieces if I said something ignorant...
 
depends where its located. If its on the X or Y then for the mothers offspring it would be simple random chance as to wether they get the good X or the normal X and both male and female would have an equal chance. If however its on the fathers X or Y then it becomes gender specific, ie if its on the X then only his daughters would get it and if its on the Y then only his sons would

However not everything IS on the X or Y which means that things can be passed by simple random chance to either gender from the father too if they are on one of the other chromozones.
 
Long long ago, about 1.5 billion years ago at present estimates, all life either just duplicated or shared genes equally with equal resources. At this time early microscopic multi-cellular organism had to reproduce and thus the first tissue types formed as sperm like cells were created to go off and seek out other "colonies" fuse with the haploid cells of the colony to grow new "colonies" inside until the mother one bursts. (see image) and so god said "let there be sex" and there was, and it was good, if only hermaphroditic.

algae-2.jpg


Now the pressure for gender kicks in the right circumstances and so it is with animals beyond flat worms tending to fall out of hermaphrodite gender mode. Here in this cause if a mutant appears that is only capable of producing sperm but no ova, this mutant and dedicate all its resources to screwing around propagating its genes rapidly, while the other had to waste time and energy making eggs. Suddenly everyone catches on to the game and there are very few honest workers making eggs, now these honest hermaphrodites are in short supply and very valuable as they are the only ones who are insured to reproduce, not being able to compete with the cheapskates around them they forgo their male genetically and dedicate all resources to the female genetically. Thus about 500 million years go god said "let there by dimorophic genders" and there was, and it was good.

The progeny could take on two behavior modes, male and risk never reproducing or being a stud, female and insure reproducing but only a limited number of offspring, from this many animals followed this mode even if it did not always make since to do it this way. Since both the male and female share most if not all the same gene in cases a hormonal mechanism was set up to dictate if male genitalia should form or female genetialia should form. This would also dictate changes in the brain for establishing set behaviors of either gender and thus god said "let thy women cook and let thy man lay in thy couch and drinkith beer, and women did cook and man did lay about most lazy and drinkith the beer, and it was good."

Well actually since men and women do share almost all genes, one would expect they share almost all behaviors, and account for individual behavioral difference, errant hormone exposure in the womb and so forth its probable that individual behavioral differences are greater then gender differences. So god said "let there be gender benders, butch women and pansy men, let there be gays and intersex people" and there was, and it was god.
 
visceral_instinct said:
Please excuse my lack of knowledge of genetics here...

So, how did we evolve so that male-typical traits - in general, anyway - pass on to males and female ones pass on to females?

Say you have Caveman X who has very good visual-spatial skills, and is more successful at hunting and providing for his children than other males, so he has more children and passes on his DNA to more individuals who also have good visual-spatial skills. His mate, Cavewoman X, has very good ability to single out small visual details, which is very useful for finding food, so she is also more fit than others of her gender.

Wouldn't their hypothetical offspring get both his visual-spatial skills and her ability to look for things in a high sensory environment, or some combination of both their traits, rather than the males inheriting one set and the females inheriting the other?

Please don't tear me to pieces if I said something ignorant...
Click to expand...

It goes beyond that into the area of simple physical characteristics.

There are exceptions, of course, as with everything. BUT in general, males had superior upper body strength which placed them in the role of protector/provider of the somewhat weaker female who's role was to give birth and nurture. And that's still pretty much the same today.
 
Read-Only said:
It goes beyond that into the area of simple physical characteristics.

There are exceptions, of course, as with everything. BUT in general, males had superior upper body strength which placed them in the role of protector/provider of the somewhat weaker female who's role was to give birth and nurture. And that's still pretty much the same today.
Click to expand...

The roles was dictated before the body type.
 
ElectricFetus said:
The roles was dictated before the body type.
Click to expand...

Exactly - which is precisely why I said "physical characteristics."

And genetic traits themselves have nothing to do with it beyond that simple fact. Sure, there are those who are genetically predisposed to be more or less masculine or feminine but those are aberrations when contrasted against the general human population.

In short, genetics completely bites the dust on this subject.
 
Thanks Asguard for explaining.

It goes beyond that into the area of simple physical characteristics.

There are exceptions, of course, as with everything. BUT in general, males had superior upper body strength which placed them in the role of protector/provider of the somewhat weaker female who's role was to give birth and nurture. And that's still pretty much the same today.
Click to expand...

I know that, I wanted to know exactly how it came about though.
 
visceral_instinct said:
I know that, I wanted to know exactly how it came about though.
Click to expand...

Well, women wanted things moved around in their caves quite a bit and only they knew where everything had to be placed so the men developed the strength by moving all those rocks and libs and stuff to make the woman very happy. Then the woman wanted the men to go out and get food for their caves to have something to eat which the men had to travel far away to get the food sometimes giving them their stamina and running abilities. Then the woman wants to be certain the men were very strong so that the women could say that they couldn't lift things or do any heavy work which made the men even stronger. So that's how it all began and how woman has always been smarter and men always stronger. :D
 
ElectricFetus said:
Long long ago, about 1.5 billion years ago at present estimates, all life either just duplicated or shared genes equally with equal resources. At this time early microscopic multi-cellular organism had to reproduce and thus the first tissue types formed as sperm like cells were created to go off and seek out other "colonies" fuse with the haploid cells of the colony to grow new "colonies" inside until the mother one bursts. (see image) and so god said "let there be sex" and there was, and it was good, if only hermaphroditic.

Now the pressure for gender kicks in the right circumstances and so it is with animals beyond flat worms tending to fall out of hermaphrodite gender mode. Here in this cause if a mutant appears that is only capable of producing sperm but no ova, this mutant and dedicate all its resources to screwing around propagating its genes rapidly, while the other had to waste time and energy making eggs. Suddenly everyone catches on to the game and there are very few honest workers making eggs, now these honest hermaphrodites are in short supply and very valuable as they are the only ones who are insured to reproduce, not being able to compete with the cheapskates around them they forgo their male genetically and dedicate all resources to the female genetically. Thus about 500 million years go god said "let there by dimorophic genders" and there was, and it was good.

The progeny could take on two behavior modes, male and risk never reproducing or being a stud, female and insure reproducing but only a limited number of offspring, from this many animals followed this mode even if it did not always make since to do it this way. Since both the male and female share most if not all the same gene in cases a hormonal mechanism was set up to dictate if male genitalia should form or female genetialia should form. This would also dictate changes in the brain for establishing set behaviors of either gender and thus god said "let thy women cook and let thy man lay in thy couch and drinkith beer, and women did cook and man did lay about most lazy and drinkith the beer, and it was good."

Well actually since men and women do share almost all genes, one would expect they share almost all behaviors, and account for individual behavioral difference, errant hormone exposure in the womb and so forth its probable that individual behavioral differences are greater then gender differences. So god said "let there be gender benders, butch women and pansy men, let there be gays and intersex people" and there was, and it was god.
Click to expand...
Great explanation of the origin of sex.
visceral_instinct said:
So, how did we evolve so that male-typical traits - in general, anyway - pass on to males and female ones pass on to females?.
Click to expand...
As has been mentioned, some traits are carried on the X or Y chromosome and so their inheritance is sex linked via the straight forward genetics. Other traits are expressed differently in males and females even though the genetics may be identical (in other words, the genotype is the same, but the phenotype is different). The reason the same gene can be expressed differently in males versus females is the influence of various hormones on the expression of those genes.

A given gene may turn on when exposed to high levels of testosterone. Another gene might turn off. This mechanism allows the few genes carried on the X and Y chromosomes to control the expression of genes on every chromosome. Thus a small genetic difference can create a large difference in phenotype.
 
As you notice, however, traits can be passed down maternally even though they're not expressed maternally. The presumption is that sex-chromosomal modifiers (probably acting in concert with X-chromosomal deactivators) fail to activate genes in one sex or another that aren't "important" to the fitness of that sex, at least as defined in the classical roles of sexual resource or work-partitioning. There's a book by a fellow named Andersson that goes into some of it. Here's the ref:

Andersson, M. 1994. Sexual selection. Princeton University Press: Princeton. 624 pp.

Good book, if a little dated now.
 
Of course gene activation in one sex varies from another, but why does it vary? Well in humans, it all starts when "Male" genes on the Y chromosomes activate the production of hormonal triggers during specific stages of fetus development, if those hormonal triggers do not happen development continues goes female from hormonal triggers on X chromosomes. These hormonal triggers do not just activate changes in morphology but also changes in the brain. A good example is inducing homosexuality in animals.

First noticed when a cow births twins with one male and the other female. The female cow invariably acts male and desires to mount other female cows, and is sterile Exposure to bursts of testosterone during specific stages of fetal development would produce homosexual and even inter-sexed attributes in female mice. Thus one can postulate that specific behavior sets in humans are induced by hormones during specific stages of fetal development, variation in hormone exposure likely explains non-stereotypical gender specific behavior, sexual preference, gender identity and intersex births.
 
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