RufusAtticus

Yes, I think all mammals, male and female, have all the appropriate tissues to produce milk and feed young, except for maybe male cetaceans.

For decent refs you'd probably have to find a mammalologist or an anatomy book.

MrDarwin

Male cats have nipples, and I'm pretty sure male dogs do too.

Another interesting and little-known fact: men can and do get breast cancer. Wouldn't happen if men didn't have breast tissue, which they don't use and don't need in the first place.

asgardhaven

Male nipples probably derive from the fact that most sex specific organs derive from a nonsex specific system in the embryo and only differentiate once the appropriate hormones start a cascade of events (the urigenital tract is a good example)

Males not having some sort of undifferentiated system to start with at least at embryo stage would mean that the female would have to build a system from scratch instead of developing a sex specific end product. I'm not sure if that sort of gene and developmental regulation is feasible in light of its greatly increased complexity.

Reldas of Melchezidec

One must not fully understand the premise or contention here.
Help me out:
The debate is over the existence of "good design" vs "Bad design" characteristics in life.

One party claims that phenomena such as complexity plus effieciency in biological systems alludes to an "intelligent designer", whatever that means.

Another party offers counterexamples of less efficient systems and wastefull complexity, alludeing to an unintelligent designer, or none, whatever that means.

A good logician can make a grand case for one side of an issue and then turn around and make as grand a case for the other side. Some issues are that subjective. Both parties can use the exact same evidence to offer what they think to be dufferent conclusions.

Everything mentioned thus far can possibly be "good" or "bad" depending on the occasion. Perhaps a long time ago, both parents provided milk for thier youg, but have since assumed different roles. It might have been a good design then! If you define every mutation, and everything else for that matter, as "neutral", then there are no good or bad traits unless you define dying and extinction as "bad", as some scientists do. However, If you define mutations in genes, as well as everything else in the universe, as designed- or good, or logos, or tao, or whatever, then where does the contention lie? If even less efficient systems are defined as good by one party, then what is there to argue against except a reality barrier?

pmurray

Probably not possible, because the immune system needs to adapt to whatever pathogens are in the environment. These things mutate faster than higher animals.

asgardhaven

quote:
Originally posted by Rhaedas

But while that's a good usage, a better design would have been to make the immune system fully functional from birth.



But then you run the danger that the timing would be off and that the immune system would start functioning in utero. That could play all sorts of havoc on the placenta and endanger the fetus. Besides the immune system is busy to start with making the self/not self decisions that pare out all those self reactive immune cells.

Kathleen13

Here is some interesting info about mammary glands:

Source: Functional Anatomy of the Vertebrates: An Evolutionary Perspective 3rd edition, Liem, Bemis, Walker, Grande


Quote:
Mammary glands contain considerable adipose tissue along the secretory cells. They secrete milk under hormonal influence only during lactation. Milk contains water, carbohydrates, fat, protein, various minerals, and antibodies. Parts of the duct system are enlarged and store milk until the young are fed. The ducts open to the surface in different ways. In monotremes, the ducts discharge into a small depression on the belly. The parent rolls over and, because monotremes have leathery bills rather than fleshy lips and cheeks and cannot suck efficiently, they young lap the milk from the hairs. Both male and female monotremes have functional glands. In other mammals, the functional glands are restricted to females, and the ducts open onto nipples or into teats.

Mammary glands are a particularly important derived feature of mammals, for they necessitate a close association between the young and mother. This association provides young mammals more time to learn to cope with the rigors of their world, and it plays a key role in the evolution of social structure in mammals.
End quote


Some other interesting points I found while browsing this section of my textbook. It seems that the hormones estrogen, progesterone and placental lactogen stimulate the ducts and mammary glands during pregnancy, but not the secretion of milk. This occurs after birth when progesterone abruptly decreases and prolactin output increases. Prolactin also promotes maternal behavior in many species. Most mammals cannot get pregnant while they are nursing young.

Perhaps this sheds some facts on the subject. I couldn't find much information on how male anatomy differs specifically. However, as quoted above, it did say that in monotremes both sexes have functional glands. I think that in most mammalian species, males have "breast" tissue, but not functional glands.

As a side note, I know that in puppies and kittens it is essential for them to get the first milk from the mother called the colostrum (milk secreted for a few days after birth characterized by high protein and antibody content). Puppies and kittens that do not get this milk are generally less healthy and much more vulnerable to illness, needing special care. In the wild however, this would, IMO, be a death sentence.