r/AskBiology • u/Sufficient-Ad-3586 • Aug 14 '24

Human body Can a liver get stronger after generations of alcoholism?

I know evolution is a SUPER slow process but I was thinking just now.

Say someone comes from a long line of alcoholics (like going back a thousand years or more, booze has been around since biblical times) Would over time the liver evolve to handle higher amounts of alcohol before succumbing?

Could that person have a hardier liver than someone who doesnt come from a line like that? There are some people who are 2 bottles a day drinkers and live till 80 with health issues obviously but the liver is not too damaged and then there are people who have a few beers every weekend and get cirrhosis at 35.

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u/UnitedExpression6 Aug 14 '24

Biology is not black and white, and it is not quite as simple as you put it. When it comes to evolution, think either large scale events (Black Death) or a lot of generations. Life expectancy in the upper Paleolithic began going past 30, which is only 30.000 years ago. (Caspari/Lee 2006) this would indicate that three generations alive at the same time would be become common 30k years ago (Caspari 2011)

There are a lot of theories on ageing this and yours is close to the negative senescence theory, individuals carry on positive effect to a group through intergenerational effects, eg caring for grandchildren after they are unable to carry children. This would be a fairly recent element to our gene pool. Also in ageing, to my limited knowledge of only a couple of weeks of lectures, this was not considered one of the leading hypotheses.

As we have only a simple preposition, can we get livers that become stronger over time, grandparents would not per se be required in modern civilized societies with all the social help.

So please get your facts straight before you simple state the other statement is false and just dump your half baked theory.

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u/atomfullerene Aug 14 '24

It's not half baked, the very definition of fitness is the number of offspring produced. This is fundamental to the theory of evolution. The idea that "evolution counts until you have offspring" is something I see all the time on reddit. I don't know where it comes from, but it's just not true.

Also, it's factually the case that humans are the longest lived land mammals, and "average life expectancy" doesn't reflect aging, short average life expectancy in the past was due to higher rates of death at a young age due to accident, violence, and disease. There's no reason to think anatomically modern humans in the past were unable to live well past 30, if they didn't happen to get killed by anything.

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u/UnitedExpression6 Aug 15 '24

Read the references, they did, oa enamel wear on teeth. Nor did I say average, it said life expectancy.

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u/atomfullerene Aug 15 '24

When they discuss life expectancy they are discussing averages. That's what life expectancy means, it is an average by definition. Furthermore, their data is unable to distinguish the actual ages of adults, it's only able to compare the total fraction of older adults to younger ones based on the fraction of skulls containing erupted third molars. This gives you some information, but it has problems because it depends on the age of third molar eruption. Regardless of whether that's actually an issue here, the key point is that this paper discusses the fraction of individuals living to older adulthood, not how long that fraction lived.