Secondary Sexual Characteristics: Natural Selection or Sexual Selection? (choice, evolution)

[Djamila]

Originally Posted by Sunstone

Do you think secondary sexual characteristics are the result of natural selection or sexual selection?

The secondary sexual characteristics are such things as body hair, developed breasts, high muscle definition (in males), and so forth that develop at puberty. How did they evolve? Were there natural selective pressures that accounted for their evolution. Pressures such as diseases, predators, weather, etc. Or, were the secondary sexual characteristics selected for through sexual selection. That is, did they evolve because potential mates found them attractive and chose to mate with those individuals who exhibited them?

For instance: Is the size and shape of female breasts the result of natural factors in the environment, or the result of males finding that size and shape of female breast attractive?

Again, is the muscle definition found in males the result of natural factors in the environment, or of females finding that definition attractive?

Most of these characteristics are the result of high levels of testosterone and estrogen, both directly linked with fertility and reproduction.

Men generally like Angelina Jolie's lips because they're a sign of high estrogen levels. Women generally like the muscular bodies of African men because they're a sign of high testosterone levels.

It's mostly biological, I think.

[Random]

Originally Posted by Seyorni

In sexual selection there's certainly choice involved, but not necessarily conscious intent. An organism can be very selective without consciously realizing it.

This doesn't make sense to me @ all. Choice does not imply conscious intent in sexual selection?! I'm awash in a sea of confusion. The prompts of attractive body-features determine the actions of a chooser?! Then it's not a choice @ all, surely...

Originally Posted by Seyorni

Sexual selection is a powerful evolutionary force, and it frequently produces negative adaptations to environmental conditions. A peacock's tail, a moose's antlers, a human's breasts, &al produce slower or clumsier individuals yet often require considerable resources to produce. It's a trade-off, inasmuch as these individuals are more sexually successful despite their handicaps. This is how evolution works, though. DNA rules. It's willing to sacrifice a few individuals to produce more copies of itself in the end

That's nice. So if I were to vote on the poll, what choice would reflect the above?

[Seyorni]

Originally Posted by Godlike

This doesn't make sense to me @ all. Choice does not imply conscious intent in sexual selection?! I'm awash in a sea of confusion. The prompts of attractive body-features determine the actions of a chooser?! Then it's not a choice @ all, surely...



That's nice. So if I were to vote on the poll, what choice would reflect the above?

The poll's flawed. There's not a single cause of secondary sexual characteristics.

[Radio Frequency X]

Originally Posted by Real Sorceror

Whenever I am presented with multiple choice, I always answer "Yes".
These secondary characteristics are the result of both natural and sexual selection.

I agree, I'd say it is both.

[fantôme profane]

Originally Posted by Seyorni

Yes, his extravagant facial hair got him all the ladies, despite rendering him half-blind and unable to eat.
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That is absolutely brilliant!!!




As to the poll question, I have to agree that secondary sexual characteristics likely come about from a mixture of both sexual selection and natural selection.

[painted wolf]

Both.

sexual selection works with the materials provided for by 'natural' selection.

an exparament was done allong this line... with finches. Male finches were put in display cages, one was given a prosthetic red feather crest, one was 'natural'.
The female finches were allowed to choose between either male.
Most of the females chose the male with the red crest, they thought it was sexy.

Now the finch isn't just going to spontaniously develop a red crest because the girls like it more... but if a mutation occures that makes a male more like the ideal then there you go, he gets selected for.

wa:do

[painted wolf]

more evidence of sexual selection....
in the Nov. 9th issue of Nature.
A frog population in the Amazon is in the process of splitting allong female preferance lines. One group of females likes males with a simple call discribed by the resercher as "Chu!Chu!"
Another group of females likes males with a more complex call discribed as "Chu hanh! Chu hanh!"
The gathered genetic evidence from the two groups of the same species showed that the genetic flow between the two groups was 30 lower than in the groups themselves.

so here is more evidence that secondary sexual characteristics (the song) is influenced strongly by the preferances of the opposite gender.

wa:do