Why human women have breasts an other mammals don't

http://www.msnbc.msn.com/id/18039615/

And other questions specumalated.

everybody Needs A Bosom For A Pillow
everybody Needs A Bosom

The argument is ridiculous. In evolutionary terms, the only thing that matters is surviving long enough to pass on genetic material. That is, maximize the number of progeny that survive to pass on their genes.

The article implies the individual woman avoids sex to avoid death - AS LONG AS YOU SUCCESFULLY RAISE the kid, evolution doesn’t care if you survive. If you’re past childhood-bearing age, you’re genetically irrelevant. You do have societal contributions for your tribe, however. If you can pull teeth, or teach the other tribemembers on how to sew up warm clothing, you help survival of the tribe as a whole.

Someone has never heard of sexual selection.

Not everything is an evolutionary imperative, either. All species have traits that are neutral in an evolutionary sense–they neither decrease nor increase odds of survival, and therefor have no impact on evolution one way or another.

Or to put it another way: some traits are just random.

Well, no, it’s unlikely that’s true in these cases. Most of the evolutionary changes to female humans made them more vulnerable to their environment, not less. Bigger breasts, fewer muscles, ect. are not strictly speaking a good change for a women living on the edge of danger and constant struggle in the natural world.

It’s like colored hair/melanin content. Although there may be some environmental forces involved it seems more likely to me these traits were being pushed by sexual selection more than environmental forces.

The stuff about orgasms, i dunno. What’s in question i think is the cost, not the payoff. On some level, basically, women need to want to get pregnant more than men need to have sex, at any particular instance, to keep the species going. Everything past that point in discussion seems mere speculation.

The article doesn’t conclude anything. It offers up competing theories. If scientists don’t yet have the answers to these questions, how are we supposed to have them.

Yeah, but sexual selection is the biggest copout in the evolutionary biology world.

“That trait showed up…because the opposite sex randomly decided to like it, and passed that preference on to their offspring!”

You can say that about anything - it’s a completely unscientific answer, as it’s patently untestable. Doesn’t mean it’s not true, just that as a scientific theory it’s horseshit.

Ack. I think you’ve stepped in one there.

The basic premise (and the starting poing in testing methodology) is that sexual selection confers physical changes that increase mating success but decreases environmental fitness.

Cow udders don’t count?

Also opposite sex doesn’t “randomly” like a trait although it seems that way often with birds.

“Not to me!”

-Willy Johnson, breast researcher

Well, if you can’t explain it with science, then you have to use religion. Therefore, The Lord maketh boobies. This is proof enough of the existence of God.

I’ve definitely seen some breasts that have made me believe in God.

And that he’s a man.

I agree this is a good starting point, but it doesn’t seem to be the main focus of the article. The author isn’t suggesting large female breasts, female orgasms, and hidden ovulation have mating benefits that outweigh the decreased environmental fitness of these adaptations. He doesn’t say much about environmental fitness at all, other than pointing out that childbirth was risky to mom’s life.

Rather than suggesting these adaptations are dangerous, he seems to be implying they are seemingly useless, since other female mammals don’t have them. Then he brings in experts to summarize theories for why the adaptations aren’t really useless.

To me, the article shows how unscientific evolutionary psychology can become. Let’s say you set up some study where you correlate female breast size with number of healthy offspring. Here’s the possible results, along with the interpretation by a hardcore evolutionary psychologist.

  1. Result: Larger breasts are associated with more offspring.
    Interpretation: See, large breasts lead to reproductive advantages. Big breast theory is supported.

  2. Result: Larger breasts are associated with fewer offspring.
    Interpretation: Today’s females have access to reliable birth control, so they have more choice over reproduction. Larger breasts originally did confer reproductive advantages. Our culture has changed, but evolution will take a long time to catch up. Big breast theory is not contradicted.

  3. Result: Breast size has no significant association with number of offspring.
    Interpretation: Variant of #2 above. Culture has changed due to advances in reproductive technology, and the evolutionary advantages of large breasts are slowly changing. Big breast theory is not contradicted.

There’s no possible result where the evolutionary hypothesis is definitively contradicted, so this hypothesis isn’t scientific, since it fails Karl Popper’s falsifiability test.

Not all of evolutionary psych is like this – there’s been a few studies that do set up falsifiable conditions. But when your evolutionary explanation can rationalize all possible findings, your scientific theory has more in common with an ideology (see Marxism or Freud for earlier academic examples).

I do think the article raises some interesting points to think about. Personally, I agree with Ben Sones; some human sexual characteristics are random byproducts of evolution, and don’t confer any reproductive benefit.

Like peacock tail feathers. The theory (as I understand it) is that female peacocks suddenly started liking male peacock feathers (or using them as a method to judge genetic fitness) and so it created evolutionary pressure to have larger and larger peacock tails.

The problem is that it’s a pat answer - you can take literally any physically distinctive sex-specific feature (human male beards! female breasts! antlers!) and ascribe it to sexual selection. It’s an entirely untestable hypothesis. Again, doesn’t mean that it isn’t true in many cases, it’s just not particularly scientific from a purist standpoint.

Edit: Sidd said it better than I did, but I’m just a simple country lawyer without his big city book learnin’

It’s not, that’s why my first response was “someone hasn’t heard of sexual selection” :).

Rather than suggesting these adaptations are dangerous, he seems to be implying they are seemingly useless, since other female mammals don’t have them.

My favorite argument against evolutionary randomness was a question i have about cholophyll. It’s stated, that at least chemically, that all cholophylls are equally effective at producing ATP. So i ask, why aren’t plants randomly colored? Because there is some small advantage, perhaps undiscovered, to the use of A and B forms.

If ALL mammals EXCEPT humans possess diminutive breasts, that doesn’t seem very random!

To me, the article shows how unscientific evolutionary psychology can become. Let’s say you set up some study where you correlate female breast size with number of healthy offspring. Here’s the possible results, along with the interpretation by a hardcore evolutionary psychologist.

You can’t really test modern human behavior patterns for reliable data on evolutionary pressures, imo. IMO, your whole test is preconceived to fail because it’s relying on modern behavior to reflect evolutionary history, and we have mostly stopped evolving (another discussion later).

It’s like saying modern women in NYC are more fashion conscious than women deep in the Bible Belt. So we must ask; how have they evolved to differentiate themselves? Do they have longer legs, fuller lips?

You guys seem to be missing the fact that not all female humans have noticeable breasts.

And some species, like peacocks, have traits that decrease the odds of survival but increase the odds of reproduction.