There is a logical fallacy that pervades many of our assumptions about current human behaviors and the evolutionary extrapolations we make. The late Stephen Jay Gould ("Male Nipples and Clitoral Ripples" in Bully for Brontosaurus) laid out a brilliant (and fun) argument against assuming that something we currently see (e.g., male nipples) must necessarily be adaptive or was adaptive in our evolutionary past. This isn't necessarily so and Gould does his usual brilliant job with a wink and his piercing intellect. For instance, It is silly and illogical to assume that men have nipples b/c somewhere in our evolutionary past we actually lactated and fed our young. The reason men have nipples is b/c women need them to feed our young--and, embryologically speaking, we all start forming in utero on the same physiological platform. So simple, so elegant. So...let's be cautious about the assumptions we make based on what we see today. This doesn't mean we can't learn from what the evolutionary psychologists put forth, it just means we have to remain good scientists.

Really a good reminder.

there's an equally impressive dawkins-ian explanation for the same phenomenon.

the only reason men have nipples is because the genes that made them that way survived and the ones that didn't have male nipples died off.

the only thing that explains why anything happens for an organism is its likelihood for longevity, fidelity, and fecundity.

Better yet: separate genes that are involved in defining sex from genes that don't. Testicles or uteri? Sure- that's going to be different, but men and women both have stomaches, eyes, teeth, and a preponderance of other organs and systems that cannot be differentiated by sex, so if nipples by themselves are part of a general human genetic template that is fit, then they will continue to appear as a species-wide trait.

Yep! Any ev psych (or evolutionary ANYTHING, for that matter) needs to keep in mind that any biological phenomena they witness may be an adaptation, by product, or noise. Not everything is an adaptation, but things that are too functionally complex to happen and be maintained by chance are.

You as a person well heeled in evolution I was wondering if you could explain to me the how nipples evolved in the original posters example.

What milk did a baby drink before a nipple evolved? How could a baby have survived until finally that competive advantage did work out? How early in mammal evolution did milk production come into effect?

It seems that evolution works over a very large time scale so it wasn't like pop there is a fully funtional nipple. No it seems that cells of a certain kind would have to begin to migrate towards or convert at the chest area. (As an aside how about explaining bilateral symmetry for nipples, surely we were locomoting around before nipples popped up so what is the mechanism by which that we ended up with two instead of one. Was it simply because two is better than one?). How were these intermidiary nipples a competive advantage that survived. Then once the first functional nipple was actually milking how long before mother and progeny did figure this out and the progeny started to feed?

You see evolution has to be far more nuanced or complicated than Darwin has proposed it to be (though his idea is elegant). To say it is doubtless evolution is just a hand waving explanation. You can see bee's in amber that are 40-60 million years old that phenotyically at least are almost if not identical to the bees of today. It is like the only evolving thing in bees was probably their behavior and maybe internal stuff like immunological responses to changing microbial assaults. But a bee has been a bee for 40-60 million years at least.

Yeah, evolution is a great yet incomplete theory for an actual hard science. As such a little more respect should be given to what is in the realm of the unknown. Something that to me many evolutionary psychology experimenters are rather callous about.

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There is a great deal of respect within EP about what is unknown; just because a handful of researchers come up with silly conclusions doesn't mean that nobody approaches the field seriously. That the opposite is true is the really troublesome (and baseless) assumption that the blog entries and a lot of the posts here have relied upon.

the natural state of the fetus is female, and certain hormones must be produced to produce a male. Tissue migration responsible for breast tissue has already differentiated/migrate to the proper spot, and doesn't fully manifest the phenotype because of hormonal milieu. PS: gynecomastia develops in a significant number of teenage boys during puberty due to the influence of estrogen, if you give men estrogen (old treatment for prostate cancer) they grow breasts...

Well, it's my understanding (from the top of my head) that the breast is, in fact, a modified sweat gland. Thing is, a full-on breast/nipple combo is not required in order to confer some selective advntage...any more than a fully functioning eye/lens combo is necessary to confer a selective advantage. Now, it's not necessarily the case that this be so, but it turns out that some animals still exhibit an in-between breast/sweat system. The platypus, for example, doesn't have teats but instead secrets milk from pores, which is then lapped up by the hatchlings. Evolution isn't going to produce an infant that needs a fully-formed teat in order to survive, until such time as such a teat is available. In the meantime, growth and support can be gradually (in evolutionary terms) shifted from metabolic investment during gestation to investment during lactation. It's not required that the system be perfect (whatever that means) to exist...just that it be better than the system that came before.

So, we may not have all the details necessary to tell a complete evolutionary narrative, but explanations exist in the context of all possible explanations. "Evolution" (and by this I assume you mean "evolution by natural selection") is considered the default explanation because there are simply no other plausible candidates that hold up under empirical or objective scrutiny.

As for the bees in the amber...well, there's no reason that natural selection wouldn't stick with a certain morphological design as long as it's working better than alternatives. There's no reason change needs to happen for the sake of change! There's nobody slapping natural selection on the ass and saying "get a move on!"

First, I'd think even a casual reading of what I've written would indicate I feel evolution is a very valid theory. That I do believe the universe is more likely to be 14 Billion some years old rather than 10,000 and I have stated that I'm a person of faith somewhere on this board.

So in that context your link to coins and creationism and evolution was not so much a new idea to me as it was an insight into you, which is favorable. But flipped coins are no explanation to how nipples evolved, they are a hand waving explanation. They are not even a close analogy. It is reasonable to assume that that analogy is far removed from how nipples evolved. :0)

I get it about marsupials.

But my complaint is that science is retarded by the lack of out of the box thinking that would see beyond Darwinian evolution simply because it is accepted as THE mechanism by which life transmutes itself. It is the details between stages of species differentiation that are usually left unexplained.

I'm not making a creationist argument at all. I see no incongruity between a creator and evolution.

As far as the bee thing goes my point was that things don't have to change for a long time. But I could propose changes to bees that would have been 'good' and reasonable mutations for them that did not transpire. As much as evolution might explain why things might change it doesn't adequately explain (to me) why things don't change.

“What milk did a baby drink before a nipple evolved?”

>>What are you talking about? Before mammals evolved the ability to lactate their ‘babies’ wouldn’t have drunk milk at all.

“How could a baby have survived until finally that competive advantage did work out?”

>>See above—at any time prior to mammals developing the ability to lactate their infants would have obtained nourishment from something other than breast milk, just as all non-mammalian infants do now.

“You see evolution has to be far more nuanced or complicated than Darwin has proposed it to be (though his idea is elegant). To say it is doubtless evolution is just a hand waving explanation. You can see bee's in amber that are 40-60 million years old that phenotyically at least are almost if not identical to the bees of today.”

>>I’m unaware of any bees preserved in amber that cannot be distinguished from extant species—can you provide an example?

“It is like the only evolving thing in bees was probably their behavior and maybe internal stuff like immunological responses to changing microbial assaults. But a bee has been a bee for 40-60 million years at least.”

>>That would be Cretotrigona prisca, which is distinguishable from contemporary species.

“Yeah, evolution is a great yet incomplete theory for an actual hard science.”

>>It’s no more incomplete than any other scientific theory (the germ theory of disease, the theory of gravitational attraction, chemical stoichiometry, etc.) Like all scientific theories it explains all observations within its scope in a comprehensive and predictive manner.

“As such a little more respect should be given to what is in the realm of the unknown.”

>>What greater respect can be given than dedicating one's efforts to rendering it known?

"But my complaint is that science is retarded by the lack of out of the box thinking that would see beyond Darwinian evolution simply because it is accepted as THE mechanism by which life transmutes itself."

>>If evidence is identified desmonstrating a requirement for something other than descent with modification to explain observations re: biological diversity of species, current theories will be revised. Until that evidence is identified, however, 'out of the box thinking' wouldn't appear to be of much utility.

Okay. The platypus example is perfect. It shows how an egg laying creature would transition to mammary feeding. Negating the need for the yoke in the egg and eventually the egg shell (it turning into a placental structure somehow).

But that first GRADUAL transitioning is usually expressed as a single incident, maybe a single brood of platypus. They could inbreed to some degree and suffer some negative repurcussion or outbreed and loose some of that "positive" evolutionary change. In-breed out-breed win loose. Then MAYBE another brood of another family is born with that GRADUAL transitioning (or something complementary) and somehow meet up with that first brood.

Do you see how descent with modification has some unsatisfactory element to it. It doesn't seem fast enough to survive a mass extinction event.

The particulars of gradual change (I'd recommend "Climbing Mount Improbable" if you haven't seen it already) are very interesting. I will say this...you're leaning towards group selectionism, which has fallen out of favor for good empirical reasons.

BTW, species which suffer mass extinction events are NOT saved by natural selection. They die. Over 99% of all species which have ever lived are now extinct...natural selection doesn't care.