I’m living with a six-month-old who has set me to pondering:
What evolutionary advantage could possibly accrue to a creature that puts absolutely everything into its mouth?
Wouldn’t logic suggest that such an apparently inherent behavior (I mean, it is a universal human trait, right?) would be disadvantageous? (Choking, cat poop, etc.)?
The only thing I can imagine it might possibly accomplish would be to weed out the offspring of inattentive caretakers. Anyone else have any other theories?
WAG’s here…
I think it’s just another way of finding stuff out about your environment. You don’t know what tastes bad until you taste it, or are old enough to understand when someone tells you. You might not know something is hard because you can’t squeeze with your hand as hard as you can bite it.
Also, one of a baby’s main functions is putting stuff in its mouth - stuff its parents give it. Bottles, pacifier, food (on a spoon), nipple, etc. There’s little else it can do. It may take the baby a little while to figure out that not everything goes in the mouth even tho mommy and daddy keep putting things in there.
And don’t forget babies who are teething have awfully sore gums. The kid may be looking for something to massage them with.
—or if it’s poisonous or fatally chokable or sharp? Nope, don’t buy it: seems to me the upside (you find out a little bit about your environment) of unsupervised, indiscriminate taste testing is far outweighed by the downside (it can kill you). Still thinking the key word is unsupervised and that it provides more or an evolutionary test for the infant’s caretaker than for the infant itself.
Again, upsides and downsides don’t come out equal for me with your suggestions. I mean, it still seems to me that providing babies with a literally uncontrollable urge to put things in their mouths puts them in at least as many—I’d even say more—dangerous situations as it does beneficial ones. And again, if a human infant (and therefore its genetic material) is in danger, how, most of the time, is it taken out of harm’s way? By a parent, who happens of course to have a vested interest in that very genetic material. If a parent is not diligent in protecting its child from environmental dangers (pebbles, razor blades), that parent’s own DNA, as carried by its child, is at stake.
Perhaps it is a side effect of having an atypically large portion (size-wise, importance-wise, activity-wise, etc.) of our brains devoted to speech? More specifically, the control that we must develop over our tongue, lips, and throat?
A guy by the name of Freud has a theory about this.
Um, no he didn’t; Freud made no attempt to address the evolutionary implications of infancy’s “oral stage.”
Instead of taking Mommy’s word for things, he tests them empirically. You are raising a true SDMB member!
The OP seems pretty reasonable, and if I wasn’t tempted to twist the supporting evidence to fit the status quo, I might have agreed. 
The deal is that human babies can’t survive without their parents. Once that’s accepted, then one can lamely say any dysfunctional behavior is okay, because the parents will stop it.
I find this argument about as satisfying as canned clam chowder.
So let’s go far back into human evolution. Imagine you’re a baby. Where are you? Either your parents are carrying you (and there’s no opportunity to eat anything), or you’re in a cave or other shelter. The ground is probably burned clean, so the worst thing you can put in your mouth is rocks, cockroaches, and cruding bedding materials. Rocks aren’t going to harm you, cockroaches are protein and improve your eye-hand coordination (sorta like an early video game), and bedding material is probably grass or other stuff that doesn’t taste good, such as pine needles.
It’s only in the last couple hundred years that a typical household contained much that was poisonous. And that was probably so valuable it was kept out of reach.
Ok, I’ve convinced myself.
“twisted evidence”? “lamely”?
What the hell’s your problem? Why do you imagine that I have some kind of hidden agenda to put forth here? Why do you drop into this discussion, out of the blue, with sarcasm and insults? And what the hell do you mean by “status quo”?
Anyway, you only address the issue of toxicity (ignoring the possibility of poisonous plants, btw), and you dismiss rocks and other such cave detritus as harmless. As anyone who’s ever spent any kind of time around an infant knows, such is not the case: if a kid can fit it into its mouth, it can probably choke on it (the kid I’m staying with had to be heimliched over a piece of bread the other day).
And to address your second paragraph. While it’s true that human babies cannot survive without their parents, it’s equally true that the parents’ DNA cannot survive without their children. So it seems likely to me that all of the factors mentioned above are likely to have contributed.
“twisted evidence”? “lamely”?
What the hell’s your problem? Why do you imagine that I have some kind of hidden agenda to put forth here? Why do you drop into this discussion, out of the blue, with sarcasm and insults? And what the hell do you mean by “status quo”?
Anyway, you only address the issue of toxicity (ignoring the possibility of poisonous plants, btw), and you dismiss rocks and other such cave detritus as harmless. As anyone who’s ever spent any kind of time around an infant knows, such is not the case: if a kid can fit it into its mouth, it can probably choke on it (the kid I’m staying with had to be heimliched over a piece of bread the other day).
And to address your second paragraph. While it’s true that human babies cannot survive without their parents, it’s equally true that the parents’ DNA cannot survive without their children. So it seems likely to me that all of the factors mentioned above are likely to have contributed.
I was applying “twisted evidence” and “lamely” to my OWN arguments, not yours. That is, the arguments I was about to state that supported the status quo.
I wouldn’t have bothered answering if I thought your perspectives were invalid.
Yeah, so, despite the confusing opener, I think partly_warmer is on your side here. Chill.
Also, I don’t think you’re guaranteed to find a clearcut list of the evolutionary advantages and disadvantages of every organism’s characteristics, along with something like a percentage for how favored a certain trait is for a certain environment. As far as I understand it, which admittedly isn’t much, that’s an overly simplistic view of the evolutionary process. Perhaps some very important traits and their influence can be traced on such a broad scale, but I think that for a situation like this, it’s not going to come down to making a list of good vs. a list of bad and seeing which is longer. A satisfactory answer, if one exists at all right now, is probably going to be complicated. So let’s discuss!