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View Full Version : Yet another evolutionary WHY question


ChrisBooth12
05-22-2010, 11:05 AM
Yes evolution happens by genetic mistakes [mutations?] from one animal to the next. Logically speaking the most suited to survive and pass on their genes does. Ok my question is why do men have a better time breaking down alcohol than women. I know men have more water percentage in their body then women so every drink we have gets watered down natually a little bit but why do we have more [better?] enzymes that help break down the alcohol? I know some fruit can fermentation by itsself but alcohol is a human invention is it not? Why can men hold it better?

DanBlather
05-22-2010, 12:16 PM
Women who get drunk are more willing to have sex, so they have more offspring. :-)

Arkcon
05-22-2010, 01:51 PM
Yeah, I saw that Cracked article too. Assuming it's correct, and I suppose Cracked citations are as good as Wikipedia's you may be getting bogged down in the typical ... why this, and why this, and why ...questions that come up when you try to explain everything in terms of some advantage evolution is supposed to provide.

Anyway, women tend to have more body fat than men, according to Cracked, that concentrates the alcohol they drink. Women don't have more body fat then men, so that they'll be drunk quicker because THAT provides evolutionary advantage -- they have more body fat for other reasons, and coincidentally, our culture of alcohol consumption has not been around long enough for selective pressure to evolve a solution. Stay tuned 'tho.

There was a comedian who said that automobile seatbelts were not designed with women's breasts in mind, and that soon "evolution" was going to "mutate" them to their shoulders, and women would start wearing football shoulder guards, instead of bras. I seem to think he thought that was going to happen by typical evolutionary processes, and be concluded in a few years time. And the whole concept is simply wrong.

http://www.cracked.com/article_18529_6-absurd-gender-stereotypes-that-science-says-are-true.html

John Mace
05-22-2010, 02:10 PM
A link to a scientific article on the subject would help. Lacking that, and assuming that the assertion is true, I'll just point out that just because something is a "human invention" doesn't mean it can't influence our evolution.

It seems that every culture has some form of alcoholic drink, we can probably assume that drinking alcohol goes back thousands and thousands of years. Could be that drinking alcohol was more of a "men's activity", and men who could handle alcohol better might be accorded higher status in the tribe.

But the simple answer, if this is in fact true, is that that we can't really know the answer to such questions. It happened some time in the past, and either conferred some benefit, or didn't confer some handicap in the reproduction race.

AHunter3
05-22-2010, 02:11 PM
Conjectural:

Some women have the enzymes etc to break down alcohol more efficiently, just as men do. Such women can "hold their liquor" better and therefore probably have a higher blood alcohol PEAK percentage, or at least reach their peaks more often which their body subsequently processes.

They get pregnant, just as the other women do, from time to time.

The ones who drink heavily more often etc are somewhat more likely to give birth to children who have alcohol-related birth defects, wouldn't you think? And therefore those children would be less likely to survive and pass along their genes?

TriPolar
05-22-2010, 02:12 PM
'survival of the fittest' is the problem here. many species have survived because they didn't live in the vicinity of a catastrophic volcano. hardly a measure of fitness. so any attribute of a surviving species doesn;t have to be a factor in survival at all.

another area i find amusing is the assumption that males and females of a species are identical except for their reproductive organs. it's pretty obvious that male and female humans are very different (sexual dimorphism), so differing metabolisms don't seem very odd.

Little Nemo
05-22-2010, 03:08 PM
You have to understand the evolution happens by a series of random events. It just points you in a certain direction, it doesn't show you where you'll end up. Nobody has a blueprint of what the final product is supposed to look like.

Imagine I take a deck of a thousand index card and I write a different number on each one. Then I shuffle them and put the deck face down. Now you come along and flip the deck over one card at a time. If the card in your hand is higher than the one you flipped over, you keep the keep the one in your hand. If the card you flipped over is higher than the one in your hand, then you discard the one in your hand and keep the one you flipped over.

Now it's easy to see that with this process, you're soon going to end up getting higher and higher cards. But you have no way of knowing if you have the highest possible card.

And two guys playing this game side by side might not have the same number on the cards in their hands. Even though they're playing by the same set of rules. They're both moving in the same direction but now at the same rate. Because of that random element.

This, to me, is evidence that supports evolution against intelligent design. If life was created by intelligent design than the creator would have created an end-product not a work in progress. By my card analogy, an intelligent designer would have just handed you whatever was the highest card rather than have you work your way through the deck.

dracoi
05-22-2010, 03:30 PM
The cracked article does not say that men have better enzymes for digesting alcohol, merely that they produce more of them. I'm assuming they mean "more per unit of body weight" since we'd already expect that a heavier man would be producing more to begin with.

Wikipedia provides some more interesting notes on the same enzyme:
Alcohol dehydrogenase activity varies between men and women, between young and old, and among populations from different areas of the world. For example, young women are unable to process alcohol at the same rate as young men because they do not express the alcohol dehydrogenase as highly. Though, the inverse is true amongst the middle-aged.[13] The level of activity may not only be dependent on level of expression but due to allelic diversity among the population. These allelic differences have been linked to region of origin. For example, populations from Europe have been found to express an allele for the alcohol dehydrogenase gene that makes it much more active than those found in populations from Asia or the Americas.

So, according to Wikipedia, middle-aged women are actually better at handling liquor than middle-aged men.

If we have to chalk this up as some specifically selected for trait, then that suggests it's about minimizing fetal alcohol syndrome - as a general rule, young women bear the kids, and middle-aged women do not. Maybe it's also a link between getting drunk and then pregnant.

But Wikipedia also mentions that the alcohol dehydrogenase enzyme digests naturally occurring alcohol, including that produced in the gut by microorganisms. There are differences in digestion between men and women. If one of those differences was higher alcohol production, then you'd also have your reason for higher enzyme levels in men.

dracoi
05-22-2010, 03:43 PM
This, to me, is evidence that supports evolution against intelligent design. If life was created by intelligent design than the creator would have created an end-product not a work in progress. By my card analogy, an intelligent designer would have just handed you whatever was the highest card rather than have you work your way through the deck.

The problem is that there is no direction, final product or highest card when it comes to survival, and that's true whether you believe in a Creator or not.

Your strongest and fastest warriors might also be the first to starve in a famine. But the ones who survive the famine might suck at being soldiers. So a species with a mix of both is a species that can survive both warfare AND famine. This is why sexual reproduction and recessive/dominant genes are so useful on a species level.

Maybe this is an even better example. We can all agree that color blindness is usually an undesirable trait that limits an individual's capabilities. However, the Air Force in WWII discovered that color blindness made a scout able to see camouflaged enemy units better than one with "perfect" vision. They relied less on color than on shape and pattern. So it turns out that this apparently undesirable genetic flaw is actually useful in certain circumstances. A species that keeps it around will be able to survive a more diverse set of challenges than an "ideal" species that eliminates the trait altogether.

Dallas Jones
05-22-2010, 04:06 PM
Evolution is not always a progression toward a better life form. Changes that are clearly advantageous to reproduction and survival of the species do tend to be promoted.

Other changes will be carried along simply because they are not clearly a disadvantage.

John Mace
05-22-2010, 04:13 PM
Evolution is not always a progression toward a better life form. Changes that are clearly advantageous to reproduction and survival of the species do tend to be promoted.

Other changes will be carried along simply because they are not clearly a disadvantage.

Mutations aren't always a progression to a better life form. "Evolution" is the natural selection of mutations that produce a better life form, where "better" is defined as better able to reproduce (in the current or future environment).

Little Nemo
05-22-2010, 04:15 PM
The problem is that there is no direction, final product or highest card when it comes to survival, and that's true whether you believe in a Creator or not.Don't overwork the analogy. My point was that evolution is a process not a destination. You can't ask why evolution gave men have one trait and didn't give women that trait because that assumes that evolution is "there" - that evolution has made its decisions about who gets what. If you ask why this trait evolved, you're assuming that evolution is something that happened in the past. Things didn't evolve - they are evolving.

Shmendrik
05-22-2010, 09:34 PM
Mutations aren't always a progression to a better life form. "Evolution" is the natural selection of mutations that produce a better life form, where "better" is defined as better able to reproduce (in the current or future environment).

No, I believe ghardester is correct. A given trait may be a side effect of another advantageous trait, but it need not be advantageous itself.

even sven
05-22-2010, 10:55 PM
Anything you get here is just going to be random speculation.

Let's take the opposite case, and say we live in a world where women are better at metabolizing alcohol than men. We could come up with few dozen reasonable-seeming explanations. Maybe men need to have better focus when they are hunting, whereas the less precise skills of gathering are not so hindered by drunkenness. Maybe women had easier access to grain stores, thus producing and presumably drinking alcohol while the men are away. Maybe men's natural risk-taking behavior is a bad combination with alcohol, whereas the more sedate women are less likely to take deadly risks under the influence.

Of course, all these explanations would be bullshit. We happen to know they are bullshit because of course the outcome isn't true. Well, the same is true for the reverse. The only thing we can do in threads like this is make stuff up and choose whatever just-so story sounds the most clever.

Blake
05-23-2010, 12:08 AM
Umm ,am I missing something? Men are bale to break down alcohol more rapidly because they are larger and have more muscle mass.

Is there any evidence at all that, absent those two factors, men actually metabolise alcohol faster than women?


So, according to Wikipedia, middle-aged women are actually better at handling liquor than middle-aged men.

No, it doesn't say that.

It says that a specific gene, is expressed more highly, in the stomach amongst middle aged, non-drinking women than maongst middl aged, non-drinking men. That's it. Nothing at all is said about ability to handle liquor. ADH is an enzyme, ie a catalyst, with a fairly long residence time, so the actual expression rate is relatively unimportant in the ability of an individual to handle liquor. Moreoever expression in the stomach is only a tiny, tiny fraction of the total biological activity responsible for being able to handle liquor. Far less important than factors such as size, past alcohol consumption,smoking or muscle mass.

If you read the actual article cited it makes absolutely no claims about actual ability to process alcohol. The Wikipedia article is, as so often, simply wrong when it states that the article makes such claims.

Be careful about the conclusions you draw form any source, and be very careful about the conclusions Wikipedia editors draw from journal articles. In my experience they are incorrect two out of three.

Hari Seldon
05-23-2010, 08:06 AM
To summarize a lot of what has been said here, evolutionary theory cannot answer "why" questions. We can make more or less plausible guesses and some of them seem almost surely correct. E.g. even eyespots are better than nothing. Eyespots in a concavity are better than that. Eyespots covered by a clear lens are better yet and so on. While this all looks pretty convincing, it is still a just-so answer.

A lot of evolution happens because things that evolved with one function (not purpose, just function) get modified and fill another one.