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18-09-2012, 12:54   #1
In Bloom
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Age of conception in pre-history?

What was probably the typical age a woman would first conceive in pre-historic times before contraception etc?

Last edited by In Bloom; 18-09-2012 at 13:09.
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19-09-2012, 18:33   #2
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Usually late teens going on modern hunter gatherer populations. Women in those societies start menstruating later than the agriculturists who followed and later again than the modern world average. Differences in nutrition(higher fat oestrogen mimics in the environment etc) seems to be driving this. Even in the western world the average age for first menses has dropped over the last couple of generations. From the link ;"A decline in the average age of menarche from 17 to 13 in Europe from 1850 to 1960 is well documented".

So first conception would be average at 19. Subsequent numbers of children would be usually evenly spaced given the contraceptive effect of breast feeding.

BTW and PS many modern hunter gatherer societies have some contraceptive techniques, barrier methods and the like and even sub cutaneous insertion of small pebbles in the male penis that shuts off the urethra(but can be retracted manually).

Last edited by Wibbs; 19-09-2012 at 18:35.
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19-09-2012, 19:13   #3
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I'm not sure what to make of the fall in the age of menarche in Europe over the past 150 years. We obviously can't extrapolate this trend straight back to prehistory or we'd have to conclude that prehistoric women didn't menstruate until their twenties or later!

How representative were the living conditions and diet of the girls in these statistics to those of our prehistoric ancestors?

I think the high age of menarche back in the 1800's probably says more about 19th century society's inability to properly feed the masses than anything else. Since then, people have been getting better nourished and healthier and the age of menarche has fallen, returning more to normal.
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19-09-2012, 19:55   #4
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So first conception would be average at 19.
Where did you get this figure from?
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20-09-2012, 10:10   #5
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Isnt this related to the hormones in our food also?
Or maybe thats just the more extreme cases.
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20-09-2012, 10:39   #6
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I'm not sure what to make of the fall in the age of menarche in Europe over the past 150 years. We obviously can't extrapolate this trend straight back to prehistory or we'd have to conclude that prehistoric women didn't menstruate until their twenties or later!
Obviously. The later menarche is found in current hunter gatherers, so it would be fair to suggest that people living the same lifestyle 20,000 years ago would be similar. Beyond that might be difficult to extrapolate as there is some odd things happening with longevity around 40,000 years ago. For some reason our species appeared to start to live longer, with no obvious change in lifestyle. Previous humans like Neandertal and Erectus seemed to have matured much earlier, so who knows when first conception kicked off in them.

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Since then, people have been getting better nourished and healthier and the age of menarche has fallen, returning more to normal.
It depends on what you define as "healthy" and "normal". Over and above the very high childhood mortality, HG's as a general rule tend to be healthier than modern populations, indeed often healthier than the early farmers that replaced them. They have significantly less problems with cardiovascular disease, dental caries, diabetes(type 2), obesity, bone density, the list is long. The earlier age of menarche may be indicative of a not so normal development.

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Where did you get this figure from?
I should have written "around 19" to be fair. If first menarche is on average 17-18 then it would follow that first conception is going to be around a year after that as periods and fertility settles down.
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20-09-2012, 12:36   #7
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I should have written "around 19" to be fair. If first menarche is on average 17-18 then it would follow that first conception is going to be around a year after that as periods and fertility settles down.
Where are you getting 17/18 as the age of menarche in prehistory?

Girls in the Kalahari tribe usually start menstruating at 16 despite their harsh lives out in the desert. I imagine our prehistoric ancestors would have generally lived in the greener areas of Africa, been better nourished with a lot more meat and fat in their diet which would have lowered menarche to about 14. Following the same pattern in the great apes, first conception would then be about 3 years after that at about 17.

That's my thinking, anyway.
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20-09-2012, 21:10   #8
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Originally Posted by Wibbs View Post
Obviously. The later menarche is found in current hunter gatherers, so it would be fair to suggest that people living the same lifestyle 20,000 years ago would be similar. Beyond that might be difficult to extrapolate as there is some odd things happening with longevity around 40,000 years ago. For some reason our species appeared to start to live longer, with no obvious change in lifestyle. Previous humans like Neandertal and Erectus seemed to have matured much earlier, so who knows when first conception kicked off in them.
Don't know if you can compare modern hunter gatherers with hunter gatherers from thousands of years ago. Those that exist today may not be an accurate sample as they are greatly outnumbered and in territories that are not "prime territory". Agriculturalists, pastoralists and everything that has come after has either swallowed up or "converted" most of the prime territory of the hunter gatherers, with the remainder existing in areas that are on the edge, hard to get to or of little use (though not for long).

You can't cheerfully extrapolate backwards.
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20-09-2012, 22:56   #9
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That's the difficulty in trying to understand the kind of society our prehistoric ancestors lived in. We can't just treat modern day hunter-gatherer societies as living fossils that perfectly represent prehistoric life.

This is the mistake many people studying the Kalahari and Hadza tribes in Africa have made and come away thinking our ancestors lived in small egalitarian bands of 20-30, ate mainly plant food gathered by the women, rarely warred with their neighbours and that the girls didn't start menstruating until after the age of 16.

This may be true for these people living out in the harsh desert regions but is that really the way our prehistoric ancestors lived?

If I were to take a guess at what our prehistoric societies would have been like I would imagine something like this:

Firstly, we wouldn't have lived out the desert . That's not a human being's natural habitat. We would have generally lived in the green savannah regions near rivers, lakes and along the coast. These richer territories would have been able to support much higher population densities than the poor desert regions and would have led to more conflicts, violence and warfare.

A lot of people are fond of pointing out the fact that in the Kalahari and Hadza tribes it's the women that bring home most of the food as if to imply that the women are somehow superior and paint the men as dumb and useless, though this is really unfair since there are few animals for the men to hunt in the poor desert regions that they occupy. In fact it's a testament to the ingenuity and physical skills of the men that they manage to catch anything. They are expert observers of animal behaviour, skilled in the use of hunting weapons and need the fitness level of a marathon runner to track down the few prey there are for hours on end.The women, by comparison, have it easy. All they have to is go to the nearest bush and pick some nuts or berries off it.

For our ancestors living the green savannahs full of herds of grazing animals it would have been the men that brought home most of the food probably in about a 65/35 ratio i.e. the men would have brought home more than they consume.

The size of the social groups they live in would have been much larger, probably 100-150. With these larger groups comes some level of social hierarchy and it's consequence, polygamy. In a tribe of 150, there would be a number of men with 2-3 wives and the very highest status man, the headman, may have had 5.

The typical age of a woman's first conception would have been lower that in the Kalahari due to better nutrition and living conditions. The average Kalahari women conceives at about 19. Our prehistoric girl living in more human friendly regions would have first conceived at 17.
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21-09-2012, 14:28   #10
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So you had already had an answer based on as much conjecture as any other theory before you asked the question? Then suitably chuffed closed your account? Fair enough. Seems odd mind you.

A couple of points;

1 not all modern HG's live in near desert environments and no one suggests they do/did. Quite the number live in lush rainforest. Jungles of SE Asia for example. Others such as the Eskimo until recently lived in another form of desert.

2 the male/female split in food gathering depends entirely on the environment, even so women tend to bring in as much as or more than the men. As far as calories go however as meat is generally more calorie rich the men bring in more on that score. Again it depends on the environment. Eskimo men bring in the lions share of calories.

5 age of first menarche depends on many factors, both environmental and genetic. The aforementioned Eskimo living the HG lifestyle women matured early, around 13, possibly down to the high calorie diet. On the genetic front Pygmy women mature early even without such a diet around 13. Interestingly they mature faster overall(and die younger) and is one reason why they're so short.

6 as for social group size this also varies depending on the culture and the environment. You can't just say "well I think our ancestors did X or did Y". Well you can, but for every example that followed that it's highly likely others didn't. Just as we see today in HG and indeed human groups overall. Goes double for reproductive strategies. Some cultures practice monogamy, some cultures don't.

So age of first menarche in HG's of the past? Bit of a crap shoot. In those not genetically predisposed to early menarche(or later, though can't think of any) it would depend on environmental pressures depending on where they were living. EG European HG's in a similar environment and diet to Eskimos likely early, the same people in a more arid Levantine environment likely later.

The most you can say about homo sapiens then and now is to observe how variable and adaptive we are with regards to food gathering, the diet itself, group size, group dynamics and reproductive strategies, so one size won't fit all.
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21-09-2012, 16:57   #11
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Eskimos? WTF you bringing up eskimos for? First you thought Fred Flintstone lived out in the desert, now you're saying he lived on an iceberg? You some kind of fukking moran?

Anyway, I think In Bloom is right and about 17 was the typical age of first conception in prehistory. Given this, wouldn't it have been in a man's reproductive interests to go for girls UNDER 17, before they've been impregnated by any other men, so that they could have all of their breeding years to themselves?
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21-09-2012, 17:17   #12
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22-09-2012, 09:29   #13
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Eskimos? WTF you bringing up eskimos for? First you thought Fred Flintstone lived out in the desert, now you're saying he lived on an iceberg?
Maybe try reading the posts again? I never suggested "Fred Flintstone lived out in the desert", nor that "he lived on an iceberg". Others mentioned the Kalahari.
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You some kind of fukking moran?
Ironic.

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Anyway, I think In Bloom is right and about 17 was the typical age of first conception in prehistory.
OK then, where? In which environment? Tropical rainforest, open savannah, temperate rainforest, steppes, sub polar regions? Modern humans and our ancestors(and previous human species) have lived in all those environments. People alive today living "prehistoric" lifestyles vary in the onset of puberty because of environmental and genetic differences, so why would that be different in the past?

Hell people living in modern societies vary in the onset of puberty depending on environment. Even in what looks like the same environment on the surface. EG African American girls mature faster and have earlier menarche than European Americans. Like I said one size won't fit all. Ditto for reproductive strategies coming off the back of that.

A few years back I read of an interesting study in New Scientist IIRC where different ethnicities in the US appeared to show different reproductive strategies. I'll try and dig up a link(though googling that should be fun). Again IIRC the study showed that African American women had more children at a younger age and outside of structured long term relationships more often. That's usually been seen as related to socioeconomic status, but the same pattern wasn't seen to the same degree among Hispanic or Asian Americans of the same socioeconomic background. European Americans of the same socioeconomic background were somewhere in the middle.
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24-09-2012, 16:41   #14
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Anyway, I think In Bloom is right and about 17 was the typical age of first conception in prehistory. Given this, wouldn't it have been in a man's reproductive interests to go for girls UNDER 17, before they've been impregnated by any other men, so that they could have all of their breeding years to themselves?
Yeah, that makes complete sense. If you imagine living in a small prehistoric society it's easy to see that committing yourself to a female and trying to get as many offspring from her over the long term would generally be the best and safest reproductive strategy, far more reliable and safer than being promiscuous. I mean, just imagine it, try and sleep around with too many mens' wives in the tribe and you'll get slaughtered .

Under this reproductive strategy, i suppose the best females to go for would those that are young and haven't been impregnated by any other men yet so that all of their breeding years would still lie ahead of them. BUT, at the same time, they shouldn't be too young, say like 5, because then you'd have to wait too long before they'd start giving you any offspring and you might die or something in the meantime. The best females would be those approaching their first pregnancy so that they would have all their breeding years ahead of them and the time you'd have to wait before they'd start reproducing would be at a minimum.

Taking 17 as the typical age of first conception this would generally mean girls in the 12-16 bracket, right?
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24-09-2012, 18:16   #15
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RIGHT?
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