Now that I've got your attention... Did anyone see that episode of "Desperate Housewives" in which the lady was still breast-feeding her five-year-old child? It took a while to unravel the mystery, but it turned out she was using it to keep her weight down. Human milk has about twenty calories per ounce. I've never had children, but I can only imagine how much milk it takes to nourish a growing five-year-old. I'm sure it takes roughly the same 1500 calories per day an old man like me needs who's not growing any more. That's 1500 calories worth of pastry, hamburgers or ice cream she can eat every day without worrying about getting fat! Probably quite a few more, since no metabolic process is anywhere near 100% efficient. Moreover--and I'm surprised the show (that show especially!) didn't raise the issue--lactation increases the size of the breasts. This is something else many women yearn for, and even go to far more extraordinary measures like implanting balloons full of silicone jelly. A woman doesn't have to have a nursing child to do this, she can buy a breast pump from any large pharmacy or off the internet. Nursing women use it to store their milk for the nanny to use while they're at work. And I'm not sure anyone does this any more in this day and age, but a young woman who wants a job as what used to be called a "wet nurse" can use it to get her own milk flowing for feeding some other lady's baby. Once she's feeding a baby the suckling will trigger production of the right hormones to keep the milk flowing, just like the breast pump does. So, my question, in this day and age when so many American women do such preposterous things in the name of keeping a trim figure: Why aren't they using breast pumps to siphon off the excess calories and make larger boobs in the bargain? Or are they? Perhaps this is one of those exposés that hasn't made it to tabloid TV yet. Please Register or Log in to view the hidden image! 'Scuse me, I've gotta go call Oprah. BTW, in case you're wondering how the episode ended, one of the DH's sneaked into the corporate child care center and surreptitiously handed the kid a carton of chocolate milk. You should have seen his eyes light up! From that moment on he never wanted his mother's milk again.
She was taking him to the day-care center at work so she could breast feed him. However, it was just a TV show. Nonetheless, I've seen it stated that there have been eras in the past when it was considered normal for children to be breast-fed far longer than they are today. I'd be curious to see an analysis of the thermodynamic efficiency. Could that be the best use of the limited food supply of a premodern people?
Maybe in times of no food or no younger sibling. But I can't imagine any woman nursing past 3. Expect these new age-comfort-coddle the kid til they are 45 parents.
Nursing to age five or so is common worldwide - until some adult teeth have grown in. I recall reading somewhere that northern Reds (polar folks, Inuit and Eskimos and such) often nursed to age 8 - until the baby teeth were largely replaced. There's a more or less clandestine movement of folks to extend nursing in the US, for the behavioral benefits as well as the physiological payoff - but in the child. I think they're shooting for something like three or four, though.
That just has to be an inefficient use of scarce food. Feeding the food directly to the child has got to be more efficient than feeding it to the mother and letting her convert it into milk. You always lose energy in any conversion process, that's what entropy is all about.
Nursing until at least age 5 has the benefits mentioned in the OP and also is a pretty effective contraceptive. Given how excesive population is stressing parts of the world, Bollywood & Hollywood's movies, and TV shows should show this often. Fraggle is correct that "You always lose energy in any conversion process, that's what entropy is all about." but mother's milk is an near perfect food to about age five. Below age 3, efficiency may be a wash as the baby can not utalized adult foods as well.
