Human Evolution - Speciation

quote:

---

Is [tolerance to alcohol] genetic though? Because I wonder how much of that might arise from the integration of the mothers and childs bloodstreams, and the exchange of chemicals and hormones et al.

---

Yep, it is genetic. Europeans have more copies of alcohol dehydrogenases (ADH) than Asians do. Europeans are able to metabolize ethanol at a prodigious rate when compared to some asians. Some asians, for instance, after one drink of alcohol get a very red face and stumble around. Europeans just get thirsty after one beer, and a little tipsy at times.Native Americans have a different problem. They drank no alcohol whatsoever before the arrival of Europeans. Many native americans metabolize alcohol through a different pathway than Europeans. This different pathway results in a highly addictive byproduct. I'll look up more info if you want.Added in edit: DOH, Mam beat me to it. Should have read the entire thread before posting. I am wondering if the alcohol dehydrogenases and aldehyde dehydrogenases are the same. ADH reacts ethanol with NAD to produce acetaldehyde and NADH. I am wondering if ADH's reverse reaction is refered to as ALDH. Anyway, that should answer your questions.This message has been edited by Loudmouth, 11-10-2004 01:01 PM

I find it interesting as well. It seems that fermenting produce served two purposes. By allowing "good" fermentation to occur the food is preserved and potable. If "bad" bacteria/yeast ferment food products then it is lost, but adding some S. cervisae is always a nice way to preserve everything from yak's milk to fruit juices to grain products. If sugars are in abundance, then the fermentation does not completely convert all sugar to ethanol which preserves the food as an energy source. Also, yeast lysis during fermentation releases vitamins such as the B complex.Of course the second purpose is social. Getting a little tipsy with your friends was perhaps the first past time (which may have eventually led to the oldest profession if you get my drift). Drinking may have helped to bond social groups as it does now.Proscriptions surrounding alcohol use in each culture became important also. There are two routes. First, being drunk on a regular basis could have been considered to be taboo. Second, those humans whose physiology could handle large amounts of alcohol were able to function better in a society that drank on a regular basis. So the evolution of human physiology and culture could have been influence by a combination of memetics and genetics.

quote:

---

On top of this, some Native Americans have a heightened addiction susceptibility genotype - meaning addiction to any chemical substance from nicotine to heroin.

---

When I wrote my original post that you quoted I was trying to remember the alternate metabolic pathway. My memory is foggy, but I thought it included a pyruvate byproduct. Either that, or I totally dreamt it up. Have you heard of this alternate alcohol metabolic pathway, or am I delusional?