10 ms·

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

173 points by zeristor 4y ago

deleted 4y ago
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sdwr 4y ago
A lot to unpack (read - wildly speculate about) here. 10,000 generations ago. Like the next one but less of a "solved game". 1000 generations ago - Old men coupling with young women reads as small-scale tribal society to me. Polygamy, pride-of-lions. Groups are small enough that village elders control the, uh, means of production. The bottleneck on food is natural stocks. 200-300 generations ago lines up with the dawn of civilization and large-scale farming (5-7000 years ago). The bottleneck on food is human labour. Young people are encouraged to start (reasonably) self-sufficient farming families, and the surplus is traded for, taxed, or stolen. 0-50 generations ago (1000AD+) ??? Cultural escape velocity is reached. Women are having children later than ever before, pointing to less risky lives, greater food security, and increased autonomy, but also a heavier load of cultural baggage. Becoming elves isn't all it's cracked up to be. Also, before someone else says it, blah blah blah average vs median.
- pronlover723 4y ago
  I watch a lot of old movies (30s-40s-50s). A ton of them have a 40s-50s man marrying a 20s woman. No idea if that was societal norm, mens fantasy, or whatever. I have to kind of believe movie execs would want the largest audience and so if 40s-50s men dating 20s women was not appealing to women of the time they'd been losing 1/2 the market. But, maybe these particular movies were the male equivalent of romance novels which seem to be written 99% for a female audience Some examples: The Girl Can't Help It (1956) South Pacific (1958) My Fair Lady (1964) The Far Country (1954) Casablanca (1942) To Have and Have Not (1944) Charade (1963) There are literally 100s of them and I'm not recommending any of the movies above per-say, but it does stick out to me just how common that theme is of man, at least 15yrs older than woman which I believe is less common today
  - midasuni 4y ago
    In the US, Men are 2-3 years older than women at first marriage and have been for a century https://www2.census.gov/programs-surveys/demo/tables/families/time-series/marital/ms2.xls https://www2.census.gov/programs-surveys/demo/tables/familie...
    - hutzlibu 4y ago
      So it seems, that those movies are mainly targeted at older mens fantasy and do not represent reality. Quelle surprise.
      - pooper 4y ago
        There is a simpler explanation. Those older men are known actors/stars who have established some influence in the industry. That or some people might buy tickets to watch movies because it has a familiar name in leading role. The combination of the two above might be enough to explain why the older men can still play lead roles in movies.
        hutzlibu 4y ago
        Well, that leads to the question, why only men were famous actors past 40, which is where the arguments becomes tautological. Because men can have attractive roles past 40 and women not, or only very rarely. I don't remember the name of the movie, but it was about greek and a female character that was 40, but the cast was not offered to a 40 year old, but a 30 year old. Because 40 year old women are not supposed to look like 40 year olds, which is where we are back to the fantasy thing. Biology is a real thing, though, men can become fathers with over 50, but women cannot. So I am not judging btw. But those fantasies are real and strong, even though they are taboo nowdays.
        metaphor 4y ago
        Biased age disparity in marriage is hardly a "fantasy" or even "taboo". I suspect if you looked at e.g. the top quintile of male earners, or those who married more than once, you're liable to see an even more pronounced gap over the aggregate median. Equally as interesting, how do wealthy divorced/widowed women marry afterwards? Poking at US presidents that stood out (i.e. more than 5 years): | President | Born | Spouse| Delta | |-----------|-------|-------|-------| | Biden | 1942 | 1951* | 9 | | Trump | 1946 | 1970* | 24 | | Reagan | 1911 | 1921* | 10 | | Kennedy | 1917 | 1929 | 12 | | Eisenhower| 1890 | 1896 | 6 | | Wilson | 1856 | 1872* | 16 | | Harrison | 1833 | 1858* | 25 | | Cleveland | 1837 | 1864 | 27 | | Arthur | 1829 | 1837 | 8 | | Hayes | 1822 | 1831 | 9 | | Lincoln | 1809 | 1818 | 9 | | Fillmore | 1800 | 1813* | 13 | | Polk | 1795 | 1803 | 8 | | Tyler | 1790 | 1820* | 30 | | Q. Adams | 1767 | 1775 | 8 | | Monroe | 1758 | 1768 | 10 | | Madison | 1751 | 1768 | 17 | | Adams | 1735 | 1744 | 9 | *: latest marriage This shortlist includes the two oldest (Biden, Trump) and youngest (Kennedy) presidents voted into office. A relevant quote attributed to Jacqueline Kennedy[1], whose second marriage was to a businessman 23 years her senior: > The first time you marry for love, the second for money, and the third for companionship. [1] https://www.forbes.com/quotes/10612/ https://www.forbes.com/quotes/10612/
- deleted 4y ago
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svnt 4y ago
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.g. lux meter, realized it was highly thermally sensitive, and instead of throwing it out or making a better one, declared they could use it to sense both light levels and room temperature.
- csomar 4y ago
  Couldn’t be accurate if they increase the sample size? They are using DNA, and we have tons of that. (Just speculating totally clueless in this area)
- rat9988 4y ago
  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.
  - deleted 4y ago
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  - waterhouse 4y ago
    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 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.
martynr 4y ago
I’m going to hazard a guess at -9 months for both sexes? :P
- tantalor 4y ago
  Yeh, the grammar is bad, more like "age of parents at conception".
  - wyldfire 4y ago
    With "conceive" (when used as a transitive verb), the subject is the parent(s) and the object is the child. There's potential for confusion because of some ambiguity but the only reading that makes sense in the context is the one intended by the author. IMO the grammar is not bad.
- intrasight 4y ago
  [flagged]
  - bufferoverflow 4y ago
    No, zero is when you're born. Conception is ~9 months before that.
    - xeromal 4y ago
      So -9 months old?
      - bufferoverflow 4y ago
        9 months from conception. Age is measured from birth.
georgeoliver 4y ago
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?
- thaumasiotes 4y ago
  A fundamental tenet of much modern science (and, especially, punditry) is that humans have completed the evolutionary process.
  - deleted 4y ago
    [deleted]
  - smt88 4y ago
    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.
    - kaba0 4y ago
      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”.
      - alserio 4y ago
        Are you implying that Cindy saying "ew" when I asked her out is not as much as natural as being mauled by a sabertooth tiger in my teens?
      - GoblinSlayer 4y ago
        Our selection process looks pretty natural to me. Also we solved food scarcity, like, a century ago?
mertd 4y ago
Somewhat grim, but this has to be disregarding the humans who never reach the reproductive age or the ones who cannot keep their offspring alive. So there is some survivorship bias baked into the methodology.
- tanbog5 4y ago
  If I understand the method correctly, they are actually determining the age that the sample's parents generated dna material that went on to create them. So everyone who has a parent is included - which is everyone who ever lived.
  - asgraham 4y ago
    They can't possibly be working with genomes spanning the past 250k years--- the oldest known human remains are only estimated to be ~230k years old, and I doubt they have parent/child trios nicely spanning the intervening few hundred thousand years. So they have to be working on mutation rate inferences. From a non-expert reading of the article, their pipeline is more like: modern human population genomes -> estimates of modern mutations' ages -> estimate of average historical parental ages. The first estimation (genome -> mutation ages) was carried out in a prior study "GEVA" [1], and this paper's contribution seems to be estimating the average parental ages based on those previously estimated historical mutation rates. I couldn't find any mention of using old DNA samples. The GEVA study pulls from two genome databases, TGP [2] and SGDP [3], both of which seem to be entirely modern genomes. I'm not an expert in the field, so maybe it's obvious to a population geneticist that these databases do include old genomes. Given that they're only using modern (surviving) genomes, the critique of survivorship bias seems valid. [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6992231/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6992231/ [2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4750478/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4750478/ [3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5161557/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5161557/
- wolverine876 4y ago
  It frustrates me that people on HN, an intelligent crowd, draw conclusions without a serious basis. Why not ask, 'Is this study disregarding the humans who never reach the reproductive age or the ones who cannot keep their offspring alive? Is there is some survivorship bias baked into the methodology?' You might find out - we might find out - rather than you guess wrong, never find out, and we all carry the error with us.
bufferoverflow 4y ago
Tbh, I thought in early humans females got pregnant at 12-15. Simply because that when they begin to have the capability to have kids.
- deleted 4y ago
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- smt88 4y ago
  Those numbers aren't constant or the same for every group of people. There are genetic pools where girls reach puberty earlier than that. Ex: https://www.nature.com/articles/ncomms8672 https://www.nature.com/articles/ncomms8672
  - leplen 4y ago
    The linked paper doesn't obviously support the claim you're making here. Maybe I've missed something? "The median age at menarche was 14.5 years (95% CI=14–15; Nindividuals=128; Nobservations=199), which is within the range of variation of modern populations."
- flatline 4y ago
  That was my thought too; but if we average over a woman’s childbearing lifespan it makes more sense.
- themitigating 4y ago
  It would be intersting to see what the average value is for primate species. When a female is able to conceive does it happen asap?
- pugets 4y ago
  To my understanding, if one mother birthed 3 children at ages 15, 20, and 25, then her age of conception would be 20. So it could be the case that women did become mothers in their teens if they also continued bearing children into their late 20s.
  - 4y ago
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kristopolous 4y ago
The perennial older male age is because men are fertile longer than women so statistics would tend to this pattern over a large enough population. There's power asymmetry, people are monsters and sexual predation is rampant but there's also biological feasibility at play here. To demonstrate, let's say that we have an imaginary equalityville where for every age pairing and sex act, there is an exactly equal one with the ages swapped - as in mathematically perfect equality. In equalityville occasionally 45 year old men sleep with 35 year old woman. But every time, a 45 year old woman sleeps with a 35 year old man, coincidentally, at the exact same time, doing equal things, in another part of town. However, 45 year old woman give birth rarely. Let's say it's 1/99th the rate of the 35 year olds. So there's 1000 45 year old women with 35 year old men resulting in 10 births 1000 45 year old men with 35 year old women resulting in 990 births Now we're going to calculate the average age based on the babies. Women (990 * 35 + 10 * 45)/1000 = 35.1 Men (990 * 45 + 10 * 35)/1000 = 44.9 And thus we get our paradox because we're counting by live births. So long as there are age delta pairings past some set of constraints, the male average will drift upward. It'd be interesting to normalize for that. This is probably doable since actual fertility statistics are well studied.
- searealist 4y ago
  And yet https://imgur.com/Ijgzwsk https://imgur.com/Ijgzwsk
  - guerrilla 4y ago
    source?
    - Renevith 4y ago
      It's linked right below the image: https://fivethirtyeight.com/features/christian-rudder-dataclysm-okcupid/ https://fivethirtyeight.com/features/christian-rudder-datacl...
  - kristopolous 4y ago
    Those metrics are culturally specific and the dataset of okcupid is limited to people who go on okcupid and volunteer answers to such questions. It's a classic case of participation bias: https://en.wikipedia.org/wiki/Participation_bias https://en.wikipedia.org/wiki/Participation_bias (see "Alf Landon wins in a landslide" for the famous example). The takeaway here is that straight single middle aged men who chase after woman, are on ok cupid looking for them, and who fill out this survey, are on average, looking for younger women. Those results cannot be seen as representative of the general population based on the methodology used here. It gets worse. Similar to the Alf Landon flaw, this could simply be exposing the demographic makeup of the site. Perhaps men think there's a promise on okcupid of younger women so it self-selects for those proclivities. Perhaps women think there's a different promise so they come accordingly. You have to extricate that. Otherwise, it'd be like going to a gay dating site, running a survey and then come out with some earth-shattering ground-breaking claim of 100% of men saying they prefer intimacy with other men. I mean, duh, look who you're asking. That's not to say these results don't hold generally, they might. But this is not evidence supporting that.
yieldcrv 4y ago
> Furthermore, fathers were consistently older, at 30.7 years on average, than mothers, at 23.2 years on average, but the age gap has shrunk in the past 5,000 years TIL: I must be having a past life regression
friend_and_foe 4y ago
I'd be willing to bet this study cannot be replicated.
jdthedisciple 4y ago
I sense overconfidence in the accuracy of the results. Wouldn't base any argument on such data.
- zeristor 4y ago
  Perhaps the researchers were more tentative but journalists need to make a story. Onus on me to read the paper. But if there were several independent strands to support it it would give it more credence.
zeristor 4y ago
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, wouldn’t father’s age at conception be similarly effected?
- deleted 4y ago
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- nprateem 4y ago
  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
  - throwawaygal7 4y ago
    The number one reason is the same reason women do post birth pelvic floor therapy...
    - nprateem 4y ago
      I think that's a secondary benefit
  - GoblinSlayer 4y ago
    After loss of virginity those two things can happen just fine.
    - nprateem 4y ago
      Precisely.
- AdrianB1 4y ago
sacnoradhq 4y ago
100 gen ago is ~ 2500 years. So that log mark ~110 gen ago is ~3k BP. A particular civilization doesn't last in a recognizable or functional form more than about 10 gen.
- int_19h 4y ago
  If 10 generations == 250 years, that sounds very debatable to me. Looking at e.g. Joseon-era Korea, did it really become a different civilization between 1500 and 1750?
ChrisMarshallNY 4y ago
That title … the way it is written, sounds like the only accurate answer is … 0. […] average age at conception […] I’m a programmer. I guess I’m used to literal interpretation.
- poulpy123 4y ago
  -9 months since it's conception and not being born
  - ChrisMarshallNY 4y ago
    Good point.
  - voisin 4y ago
    [flagged]
  - geomark 4y ago
    Some cultures count the nine months in the womb. So you are nine months old on your date of birth.
poulpy123 4y ago
I'm really surprised that 30-40000 years ago the average age of conception was 35 for men and 24 for women
- stargazer-3 4y ago
  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.
  - b112 4y ago
    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.
    - saalweachter 4y ago
      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.
    - frabcus 4y ago
      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.
    - jojobas 4y ago
      If you can survive to menopause. The average of 24+ years old appears way too high, as it was common in the old extant cultures to bear from age 14 or even less.
      - AdrianB1 4y ago
yawpitch 4y ago
Amazing that, just a century after Einstein, modern science has progressed to the point of not only having developed time travel, but also the means to get a not-yet-blastocyst to reliably communicate “you’re about nine months early, genius” in untold numbers of dead and/or dying languages.
Lio 4y ago
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.
- UncleEntity 4y ago
  Or just didn’t have kids. I was watching some random show where they were talking about the reproduction rates in the former Soviet Union and large events (like world wars) have lasting effects on birth rates that echo through time approximately every twenty years.

173 points by zeristor 4y ago

deleted 4y ago

[deleted]

sdwr 4y ago

A lot to unpack (read - wildly speculate about) here. 10,000 generations ago. Like the next one but less of a "solved game". 1000 generations ago - Old men coupling with young women reads as small-scale tribal society to me. Polygamy, pride-of-lions. Groups are small enough that village elders control the, uh, means of production. The bottleneck on food is natural stocks. 200-300 generations ago lines up with the dawn of civilization and large-scale farming (5-7000 years ago). The bottleneck on food is human labour. Young people are encouraged to start (reasonably) self-sufficient farming families, and the surplus is traded for, taxed, or stolen. 0-50 generations ago (1000AD+) ??? Cultural escape velocity is reached. Women are having children later than ever before, pointing to less risky lives, greater food security, and increased autonomy, but also a heavier load of cultural baggage. Becoming elves isn't all it's cracked up to be. Also, before someone else says it, blah blah blah average vs median.

pronlover723 4y ago
I watch a lot of old movies (30s-40s-50s). A ton of them have a 40s-50s man marrying a 20s woman. No idea if that was societal norm, mens fantasy, or whatever. I have to kind of believe movie execs would want the largest audience and so if 40s-50s men dating 20s women was not appealing to women of the time they'd been losing 1/2 the market. But, maybe these particular movies were the male equivalent of romance novels which seem to be written 99% for a female audience Some examples: The Girl Can't Help It (1956) South Pacific (1958) My Fair Lady (1964) The Far Country (1954) Casablanca (1942) To Have and Have Not (1944) Charade (1963) There are literally 100s of them and I'm not recommending any of the movies above per-say, but it does stick out to me just how common that theme is of man, at least 15yrs older than woman which I believe is less common today
- midasuni 4y ago
  In the US, Men are 2-3 years older than women at first marriage and have been for a century https://www2.census.gov/programs-surveys/demo/tables/families/time-series/marital/ms2.xls https://www2.census.gov/programs-surveys/demo/tables/familie...
  - hutzlibu 4y ago
    So it seems, that those movies are mainly targeted at older mens fantasy and do not represent reality. Quelle surprise.
    - pooper 4y ago
      There is a simpler explanation. Those older men are known actors/stars who have established some influence in the industry. That or some people might buy tickets to watch movies because it has a familiar name in leading role. The combination of the two above might be enough to explain why the older men can still play lead roles in movies.
      - hutzlibu 4y ago
        Well, that leads to the question, why only men were famous actors past 40, which is where the arguments becomes tautological. Because men can have attractive roles past 40 and women not, or only very rarely. I don't remember the name of the movie, but it was about greek and a female character that was 40, but the cast was not offered to a 40 year old, but a 30 year old. Because 40 year old women are not supposed to look like 40 year olds, which is where we are back to the fantasy thing. Biology is a real thing, though, men can become fathers with over 50, but women cannot. So I am not judging btw. But those fantasies are real and strong, even though they are taboo nowdays.
        metaphor 4y ago
        Biased age disparity in marriage is hardly a "fantasy" or even "taboo". I suspect if you looked at e.g. the top quintile of male earners, or those who married more than once, you're liable to see an even more pronounced gap over the aggregate median. Equally as interesting, how do wealthy divorced/widowed women marry afterwards? Poking at US presidents that stood out (i.e. more than 5 years): | President | Born | Spouse| Delta | |-----------|-------|-------|-------| | Biden | 1942 | 1951* | 9 | | Trump | 1946 | 1970* | 24 | | Reagan | 1911 | 1921* | 10 | | Kennedy | 1917 | 1929 | 12 | | Eisenhower| 1890 | 1896 | 6 | | Wilson | 1856 | 1872* | 16 | | Harrison | 1833 | 1858* | 25 | | Cleveland | 1837 | 1864 | 27 | | Arthur | 1829 | 1837 | 8 | | Hayes | 1822 | 1831 | 9 | | Lincoln | 1809 | 1818 | 9 | | Fillmore | 1800 | 1813* | 13 | | Polk | 1795 | 1803 | 8 | | Tyler | 1790 | 1820* | 30 | | Q. Adams | 1767 | 1775 | 8 | | Monroe | 1758 | 1768 | 10 | | Madison | 1751 | 1768 | 17 | | Adams | 1735 | 1744 | 9 | *: latest marriage This shortlist includes the two oldest (Biden, Trump) and youngest (Kennedy) presidents voted into office. A relevant quote attributed to Jacqueline Kennedy[1], whose second marriage was to a businessman 23 years her senior: > The first time you marry for love, the second for money, and the third for companionship. [1] https://www.forbes.com/quotes/10612/ https://www.forbes.com/quotes/10612/
deleted 4y ago
[deleted]

svnt 4y ago

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.g. lux meter, realized it was highly thermally sensitive, and instead of throwing it out or making a better one, declared they could use it to sense both light levels and room temperature.

csomar 4y ago
Couldn’t be accurate if they increase the sample size? They are using DNA, and we have tons of that. (Just speculating totally clueless in this area)
rat9988 4y ago
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.
- deleted 4y ago
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- waterhouse 4y ago
  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 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.

martynr 4y ago

I’m going to hazard a guess at -9 months for both sexes? :P

tantalor 4y ago
Yeh, the grammar is bad, more like "age of parents at conception".
- wyldfire 4y ago
  With "conceive" (when used as a transitive verb), the subject is the parent(s) and the object is the child. There's potential for confusion because of some ambiguity but the only reading that makes sense in the context is the one intended by the author. IMO the grammar is not bad.
intrasight 4y ago
[flagged]
- bufferoverflow 4y ago
  No, zero is when you're born. Conception is ~9 months before that.
  - xeromal 4y ago
    So -9 months old?
    - bufferoverflow 4y ago
      9 months from conception. Age is measured from birth.

georgeoliver 4y ago

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?

thaumasiotes 4y ago
A fundamental tenet of much modern science (and, especially, punditry) is that humans have completed the evolutionary process.
- deleted 4y ago
  [deleted]
- smt88 4y ago
  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.
  - kaba0 4y ago
    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”.
    - alserio 4y ago
      Are you implying that Cindy saying "ew" when I asked her out is not as much as natural as being mauled by a sabertooth tiger in my teens?
    - GoblinSlayer 4y ago
      Our selection process looks pretty natural to me. Also we solved food scarcity, like, a century ago?

mertd 4y ago

Somewhat grim, but this has to be disregarding the humans who never reach the reproductive age or the ones who cannot keep their offspring alive. So there is some survivorship bias baked into the methodology.

tanbog5 4y ago
If I understand the method correctly, they are actually determining the age that the sample's parents generated dna material that went on to create them. So everyone who has a parent is included - which is everyone who ever lived.
- asgraham 4y ago
  They can't possibly be working with genomes spanning the past 250k years--- the oldest known human remains are only estimated to be ~230k years old, and I doubt they have parent/child trios nicely spanning the intervening few hundred thousand years. So they have to be working on mutation rate inferences. From a non-expert reading of the article, their pipeline is more like: modern human population genomes -> estimates of modern mutations' ages -> estimate of average historical parental ages. The first estimation (genome -> mutation ages) was carried out in a prior study "GEVA" [1], and this paper's contribution seems to be estimating the average parental ages based on those previously estimated historical mutation rates. I couldn't find any mention of using old DNA samples. The GEVA study pulls from two genome databases, TGP [2] and SGDP [3], both of which seem to be entirely modern genomes. I'm not an expert in the field, so maybe it's obvious to a population geneticist that these databases do include old genomes. Given that they're only using modern (surviving) genomes, the critique of survivorship bias seems valid. [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6992231/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6992231/ [2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4750478/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4750478/ [3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5161557/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5161557/
wolverine876 4y ago
It frustrates me that people on HN, an intelligent crowd, draw conclusions without a serious basis. Why not ask, 'Is this study disregarding the humans who never reach the reproductive age or the ones who cannot keep their offspring alive? Is there is some survivorship bias baked into the methodology?' You might find out - we might find out - rather than you guess wrong, never find out, and we all carry the error with us.

bufferoverflow 4y ago

Tbh, I thought in early humans females got pregnant at 12-15. Simply because that when they begin to have the capability to have kids.

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smt88 4y ago
Those numbers aren't constant or the same for every group of people. There are genetic pools where girls reach puberty earlier than that. Ex: https://www.nature.com/articles/ncomms8672 https://www.nature.com/articles/ncomms8672
- leplen 4y ago
  The linked paper doesn't obviously support the claim you're making here. Maybe I've missed something? "The median age at menarche was 14.5 years (95% CI=14–15; Nindividuals=128; Nobservations=199), which is within the range of variation of modern populations."
flatline 4y ago
That was my thought too; but if we average over a woman’s childbearing lifespan it makes more sense.
themitigating 4y ago
It would be intersting to see what the average value is for primate species. When a female is able to conceive does it happen asap?
pugets 4y ago
To my understanding, if one mother birthed 3 children at ages 15, 20, and 25, then her age of conception would be 20. So it could be the case that women did become mothers in their teens if they also continued bearing children into their late 20s.
- 4y ago

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kristopolous 4y ago

The perennial older male age is because men are fertile longer than women so statistics would tend to this pattern over a large enough population. There's power asymmetry, people are monsters and sexual predation is rampant but there's also biological feasibility at play here. To demonstrate, let's say that we have an imaginary equalityville where for every age pairing and sex act, there is an exactly equal one with the ages swapped - as in mathematically perfect equality. In equalityville occasionally 45 year old men sleep with 35 year old woman. But every time, a 45 year old woman sleeps with a 35 year old man, coincidentally, at the exact same time, doing equal things, in another part of town. However, 45 year old woman give birth rarely. Let's say it's 1/99th the rate of the 35 year olds. So there's 1000 45 year old women with 35 year old men resulting in 10 births 1000 45 year old men with 35 year old women resulting in 990 births Now we're going to calculate the average age based on the babies. Women (990 * 35 + 10 * 45)/1000 = 35.1 Men (990 * 45 + 10 * 35)/1000 = 44.9 And thus we get our paradox because we're counting by live births. So long as there are age delta pairings past some set of constraints, the male average will drift upward. It'd be interesting to normalize for that. This is probably doable since actual fertility statistics are well studied.

searealist 4y ago
And yet https://imgur.com/Ijgzwsk https://imgur.com/Ijgzwsk
- guerrilla 4y ago
  source?
  - Renevith 4y ago
    It's linked right below the image: https://fivethirtyeight.com/features/christian-rudder-dataclysm-okcupid/ https://fivethirtyeight.com/features/christian-rudder-datacl...
- kristopolous 4y ago
  Those metrics are culturally specific and the dataset of okcupid is limited to people who go on okcupid and volunteer answers to such questions. It's a classic case of participation bias: https://en.wikipedia.org/wiki/Participation_bias https://en.wikipedia.org/wiki/Participation_bias (see "Alf Landon wins in a landslide" for the famous example). The takeaway here is that straight single middle aged men who chase after woman, are on ok cupid looking for them, and who fill out this survey, are on average, looking for younger women. Those results cannot be seen as representative of the general population based on the methodology used here. It gets worse. Similar to the Alf Landon flaw, this could simply be exposing the demographic makeup of the site. Perhaps men think there's a promise on okcupid of younger women so it self-selects for those proclivities. Perhaps women think there's a different promise so they come accordingly. You have to extricate that. Otherwise, it'd be like going to a gay dating site, running a survey and then come out with some earth-shattering ground-breaking claim of 100% of men saying they prefer intimacy with other men. I mean, duh, look who you're asking. That's not to say these results don't hold generally, they might. But this is not evidence supporting that.

yieldcrv 4y ago

> Furthermore, fathers were consistently older, at 30.7 years on average, than mothers, at 23.2 years on average, but the age gap has shrunk in the past 5,000 years TIL: I must be having a past life regression

friend_and_foe 4y ago

I'd be willing to bet this study cannot be replicated.

jdthedisciple 4y ago

I sense overconfidence in the accuracy of the results. Wouldn't base any argument on such data.

zeristor 4y ago
Perhaps the researchers were more tentative but journalists need to make a story. Onus on me to read the paper. But if there were several independent strands to support it it would give it more credence.

zeristor 4y ago

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, wouldn’t father’s age at conception be similarly effected?

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nprateem 4y ago
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
- throwawaygal7 4y ago
  The number one reason is the same reason women do post birth pelvic floor therapy...
  - nprateem 4y ago
    I think that's a secondary benefit
- GoblinSlayer 4y ago
  After loss of virginity those two things can happen just fine.
  - nprateem 4y ago
    Precisely.
AdrianB1 4y ago

sacnoradhq 4y ago

100 gen ago is ~ 2500 years. So that log mark ~110 gen ago is ~3k BP. A particular civilization doesn't last in a recognizable or functional form more than about 10 gen.

int_19h 4y ago
If 10 generations == 250 years, that sounds very debatable to me. Looking at e.g. Joseon-era Korea, did it really become a different civilization between 1500 and 1750?

ChrisMarshallNY 4y ago

That title … the way it is written, sounds like the only accurate answer is … 0. […] average age at conception […] I’m a programmer. I guess I’m used to literal interpretation.

poulpy123 4y ago
-9 months since it's conception and not being born
- ChrisMarshallNY 4y ago
  Good point.
- voisin 4y ago
  [flagged]
- geomark 4y ago
  Some cultures count the nine months in the womb. So you are nine months old on your date of birth.

poulpy123 4y ago

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

stargazer-3 4y ago
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.
- b112 4y ago
  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.
  - saalweachter 4y ago
    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.
  - frabcus 4y ago
    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.
  - jojobas 4y ago
    If you can survive to menopause. The average of 24+ years old appears way too high, as it was common in the old extant cultures to bear from age 14 or even less.
    - AdrianB1 4y ago

yawpitch 4y ago

Amazing that, just a century after Einstein, modern science has progressed to the point of not only having developed time travel, but also the means to get a not-yet-blastocyst to reliably communicate “you’re about nine months early, genius” in untold numbers of dead and/or dying languages.

Lio 4y ago

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.

UncleEntity 4y ago
Or just didn’t have kids. I was watching some random show where they were talking about the reproduction rates in the former Soviet Union and large events (like world wars) have lasting effects on birth rates that echo through time approximately every twenty years.