Men age faster 'because of Stone Age sex'

http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2007/10/17/scisex117.xml

by amichail • 19 years ago

8 20 19 years ago

telegraph.co.uk

staunch• 19 years ago

I have a totally uneducated hypothesis that women are more prone to casual bisexuality and it's inherently more acceptable because they were kept in harems in prehistoric time.

falsestprophet3• 19 years ago

That does not make a great deal of sense from an evolutionary perspective. For bisexuality to be selected for in women, it would have to confer an evolutionary advantage. I would guess that it simply has not been selected against because it does not confer a great disadvantage.

However, tolerance for homosexual acts between men seems to be strongly selected against. Creating sperm is expensive and wasting them with a man is not to your advantage. It was also important for men to be highly focused on interfacing with females; females could be apathetic and reproduce, because they didn't really have a choice.

brenda902102• 19 years ago

> However, tolerance for homosexual acts between men seems to be strongly selected against

Actually historically there were numerous instances of largely-homosexual civilizations. Just look up the true story behind the movie 300.

> Creating sperm is expensive and wasting them with a man is not to your advantage.

I think you completely forgot about masturbation, which pretty much destroys that entire line of argument ;) Males "waste" sperm on a constant basis. :)

> It was also important for men to be highly focused on interfacing with females

Actually in many societies men were NOT focused on social interaction with females, a trend that continues to this day especially in certain religious countries. Interaction was and is often limited to reproduction, with gender segregation in social roles (the men spend most of their time with other men while the women spend most of their time with other women and children).

It really doesn't take much effort at all to get a female pregnant. The vast majority of effort is in child-rearing, not procreation. Homosexuality actually confers some advantages, such as:

- Male bonding, leading to more effective teamwork, which is a huge advantage in small tribal societies;

- Exclusively-homosexual males don't compete for females yet can still lend their muscle to protecting the tribe.

In a small tribe, competition for females can lead to infighting which will put the whole group at a disadvantage to a neighboring tribe that has the same gender split but in which most of its males are homosexual. (Effeminate homosexuals tend to be much less common than non-effeminate ones, which is why so many gay males can fly under the radar.)

davidw3• 19 years ago

I'm not sure I buy it. Most hunter gatherer societies that still exist don't really have harems. Maybe two or three wives in some cases, but my understanding was that big harems didn't really come about until the dawn of agriculture.

timr3• 19 years ago

The dawn of agriculture was somewhere around 10,000 years ago. Even assuming that you're right, that's (conservatively) over 300 generations of polygamy.

davidw3• 19 years ago

Sure, but their argument centers around the stone age, which ends with the development of agriculture.

ced3• 19 years ago

Not very convincing. 1. Why do men reach puberty later than females? 2. Men can have children even when they're very old, women can't. This should promote longer lifespans.

Here's another hypothesis. Quoting the Wikipedia article on the Medawar theory of ageing:

"Nature is a highly competitive place, and almost all animals in nature die before they attain old age. Therefore, there is not much motivation to keep the body fit for the long haul - not much selection pressure for traits that would maintain viability past the time when most animals would be dead anyway, killed by predators or disease or by accident."

This is particularly true for men, who were (and still are, to an extent) usually doing more dangerous jobs than women. Thus, they die from accidents or predation earlier, so there is less selective pressure for genes that promote healthy organs in old age.

Another possible scenario: there is more variation in male traits than in females, and age is more than linearly dependent on these traits. Thus, even if E[X] is the same for males and females, for some trait X, the average age E[X^n] will be lower for males.

Evolutionary biology is full of reasonable-sounding explanations for just about anything. As far as I can tell, Occam does not often apply, unfortunately.

timr3• 19 years ago

Don't slight the entire field of evolutionary biology just because you don't like what you read in a tabloid newspaper. I hope you realize that there's usually a bit more to these stories than you'll find in a four-paragraph newsprint blurb.

ced3• 19 years ago

Yeah, I know. I meant to say that the article is not very convincing and thus that it (arguably) shouldn't deserve much attention. I feel the same way about most science articles in the mainstream press.

Unlike all the other hard sciences I know, it is very hard to demonstrate or contradict anything in evolutionary biology. Thus, one should be especially careful when reading about it.

jsmcgd• 19 years ago

Point of interest: The Telegraph is not a tabloid but a broadsheet.

sbh• 19 years ago

I think you are contradicting yourself:

1. Women can't have children when they are old.

2. Women have genes that promote healthy organs in old age.

So how exactly can those genes be selected through evolution, if the advantage they give doesn't have effect on the number of offsprings.

ced3• 19 years ago

Women could have genes that promote old age so that they can feed and raise their children longer. Children of long-living mothers have a better chance of survival, and thus a selective advantage, all other things being equal.

My point is not to prove my personal "theory" about women living longer than men. Rather, I contend that there is almost never One True Cause for anything in evolution. All we can do is propose many different competing factors, and say, with a lot of hand-waving, that factor X was the most important in such and such cases. Newspapers often translate that into "Y happened because of X", but that's just bad reporting.

whacked_new• 19 years ago

In some ways this is a chicken and egg problem, and the conclusions in this article are not satisfactory.

http://www.hno.harvard.edu/gazette/1998/10.01/WhyWomenLiveLo... "Studying people who live 100 years and more leads Harvard researchers to conclude that menopause is a major determinant of the life spans of both women and men."

http://www.sciencedaily.com/releases/2006/05/060526083618.ht... Study about birds, but interesting: "Elevated testosterone levels increased activity--possibly attracting more predators--made the male, dark-eyed juncos more susceptible to disease and shortened their lifespan."

And I won't go into estrogen.

sabat• 19 years ago

1- This doesn't belong here.

2- Reductive, over-generalized and oversimplified.

3- Men don't age faster. They often die slightly younger (more like 3 years rather than the stated 5). Men age more slowly and gracefully (if you have to generalize). Don't believe it? Take a look around you.

mechanical_fish• 19 years ago

Who knows what this study says, let alone how valid it is? Like just about every newspaper article about science, this Telegraph article absolutely sucks.

Here's what was the original journal article was supposedly about:

"...the difference in life span between males and females... grows in direct proportion to the degree to which an animal's society is polygynous."

Great! These folks have apparently plotted a graph, where X is an animal society's "degree of ploygyny" and Y is the lifespan difference. The shape of that graph is the entire point of this study. It would be interesting to see it.

How many of the data points from that graph made it into the newspaper? Half of one data point. We learn that the male-female lifespan difference among modern humans is 5 years out of 80. (This is, of course, probably the least useful piece of data in the entire dataset, because modern humans live a lifestyle utterly different from that of all previous humans, let alone most other animals.)

The scientists might well have data about polygyny in humans, but it's not shown here. They certainly have data about polygyny and lifespans in other creatures -- but it's not shown here. If the damned reporter had just given us the numbers for one creature -- dare I suggest the chimpanzee? -- we would know a lot more about the original study and how much it applies to humans.

But no! Instead the article tells me that women live longer than men (duh!) and that modern human societies tend more toward polygyny than toward polyandry. (Double duh.) Gee, thanks.

Sorry about the rant, but this sort of thing is intensely frustrating to me. People wonder why the public doesn't understand how science works. Perhaps one reason is that the average person never sees any actual data.

Men age faster 'because of Stone Age sex'

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