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Study reveals average age at conception for men vs. women over past 250k years

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Re: Study reveals average age at conception for men vs. women over past 250k years

#101
post #83
post #4

It seems they used modern human mutation rates, which vary by ~300%, to predict age at reproduction. Since the relationship between this rate in parents and the offspring even a few generations back does not seem to be particularly well understood, it seems they would have a hard time reaching back very far into history with this analysis and claiming any accuracy at all. To me it reads like someone bought a cheap e.…

This point was already addressed in the research. It is tiring to see this low effort comments on every research thread, thinking that the researchers are idiots and there is no need to read the article to reject it.

Can you point to the text that addresses this? The closest thing I see in the article is this paragraph:

Children's DNA inherited from their parents contains roughly 25 to 75 new mutations, which allows scientists to compare the parents and offspring, and then to classify the kind of mutation that occurred. When looking at mutations in thousands of children, IU researchers noticed a pattern: The kinds of mutations that children get depend on the ages of the mother and the father.

Later: Hahn, Wang and their co-authors built a model that uses de novo mutations—a genetic alteration that is present for the first time in one family member as a result of a variant or mutation in a germ cell of one of the parents or that arises in the fertilized egg during early embryogenesis—to separately estimate the male and female generation times[...]

So, it is saying it can measure results for male and female parents separately. But can their analysis of the "kinds" of mutations tell the difference between e.g. "30yo mother, 45yo father" or "20yo mother, 30yo father, plus lots of environmental factors that increase mutations"? The article doesn't make that clear to me.

The article links to the study (at "10.0.4.102" instead of a domain name?), but the link doesn't load... Ok, there is a working link at the bottom: https://www.science.org/doi/10.1126/sciadv.abm7047

I skimmed the study around all the matches for the strings "mutat" and "environ", and this was the best I found: Estimates of the error in our model fit do not show increasing error with either genetic or geographic distance from Iceland (figs. S6 and S7), the origin of the pedigreed mutation data used to train our model. Such a trend may have been expected if differences in mutational spectra were driven by genetic or environmental differences among populations.

The last sentence is actually ambiguous, but I think it's saying "If environmental factors tended to mess with mutational spectra, then we might expect to see X, which we did not see." It's still not clear to me how possible it is for there to be environmental factors that generate the same mutational patterns as higher age. And the only other "environ" match is in a sentence about what affects the age at which people have children.

Re: Study reveals average age at conception for men vs. women over past 250k years

#102
No one seems to have mentioned the affects of war and dangerous jobs on these stats.

After the first world war, for example, a large number of young men were gone. You can see the memorials with names on in any town or city in Europe.

The women of that generation would have competed with older women for older men as potential partners if they wanted children.

Re: Study reveals average age at conception for men vs. women over past 250k years

#103

I'm really surprised that 30-40000 years ago the average age of conception was 35 for men and 24 for women

If a woman bears many children throughout her life, you can still have a situation where the first pregnancy occurs much earlier than today's average yet the overall conception average is roughly same as nowadays.

Re: Study reveals average age at conception for men vs. women over past 250k years

#104

A few points, female fertility declines steeply past 40, but males not so much, so older males could conceivably father children with other females. Dare I say it, and this may just be not right, Genghis Khan is purportedly supposed to have fathered thousands of children it is said he had 500 or so secondary wives (citation needed). Since average (mean) income is famously a bit pointless due to a few very rich people…

Men with harems perfectly explains history's obsession with virgins. 1. No man wanted to raise another's child (as far as evolution is concerned, that doesn't lead to replication of ones own genetic material) 2. Less risk of VD, which would seriously affect your ability to utilise the harem

The number one reason is the same reason women do post birth pelvic floor therapy...

Re: Study reveals average age at conception for men vs. women over past 250k years

#105

The link to the paper wasn't loading for me. But I would love to see the reasons for extrapolating present-day biology back 250k years?

It's weird—the link in the article body goes to some sketchy IP address, but the "More information" section after the article has what looks to be the real link: https://www.science.org/doi/10.1126/sciadv.abm7047

Re: Study reveals average age at conception for men vs. women over past 250k years

#106

I'm really surprised that 30-40000 years ago the average age of conception was 35 for men and 24 for women

If a woman bears many children throughout her life, you can still have a situation where the first pregnancy occurs much earlier than today's average yet the overall conception average is roughly same as nowadays.

Even 200 years ago, it was common for women to give birth 10 times.

I bet 100k years ago, some women were pregnant yearly, from teenage to menopause.

Re: Study reveals average age at conception for men vs. women over past 250k years

#107
post #43
post #16

Earlier quoted context omitted.

There are no modern scientists who understand evolution and think it can be "completed" or that humans have done so. If you stand by your assertion, please provide evidence.

Not parent commenter, but what can be argued is that evolutions “rules” are way different to us then to any other animal (except the ones we closely handle ourselves). E.g. healing people, far smaller infant death rates, no basically no food scarcity from natural causes, etc. Our selection process is societal, not “natural”.

> Our selection process is societal, not “natural”

That's culture, not evolution. It's absolutely natural (in every sense of the word) and there are biological components.

Outside of that, though, there is also physical natural selection that occurs. Human "hardware" is evolving along with the "software".

Re: Study reveals average age at conception for men vs. women over past 250k years

#108
post #16

Earlier quoted context omitted.

There are no modern scientists who understand evolution and think it can be "completed" or that humans have done so. If you stand by your assertion, please provide evidence.

> There are no modern scientists who understand evolution and think it can be "completed" or that humans have done so. There are many modern scientists who don't understand evolution.

> There are many modern scientists who don't understand evolution.

A. I doubt there are many who don't understand natural selection and/or want to talk about evolution without understanding it

B. I excluded those people explicitly, so what's your point?

Re: Study reveals average age at conception for men vs. women over past 250k years

#109
post #106

Earlier quoted context omitted.

If a woman bears many children throughout her life, you can still have a situation where the first pregnancy occurs much earlier than today's average yet the overall conception average is roughly same as nowadays.

Even 200 years ago, it was common for women to give birth 10 times. I bet 100k years ago, some women were pregnant yearly, from teenage to menopause.

These numbers also reflect the children that survived.

If men were begetting from a young age 100k years ago, and most of their children died until they were older and more experienced, those early children are lost from the DNA record.

Re: Study reveals average age at conception for men vs. women over past 250k years

#110
post #106

Earlier quoted context omitted.

If a woman bears many children throughout her life, you can still have a situation where the first pregnancy occurs much earlier than today's average yet the overall conception average is roughly same as nowadays.

Even 200 years ago, it was common for women to give birth 10 times. I bet 100k years ago, some women were pregnant yearly, from teenage to menopause.

According to the book Sapiens it depended on resources, but women often breast fed for 4 or 5 years partly as a way to spread out and reduce number of children. The need for lots of children was a consequence of farming and industrialisation and exponential growth.
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