Freeze sperm at 18, bioethicist urges men.

ancapailldorcha

Recent article in the BBC (1) reporting that Dr. Kevin Smith of Abertay University in Dundee has suggested that men freeze their sperm at 18 to avert a rise in the number of people suffering from genetic disorders (2). The average age of fathers at the birth of their child was 32.9 in 2013, up from 31.1 in 1993 (3). As men age, mutations accumulate in their sperm due to cell division (4). However, most of these mutations are benign leading to many academics stating that the risks of men having children in later life are minor.

I'm not sure myself. Fatherhood isn't something I think about often as having a child is a 2-person process. What do ye think? Would you consider having sperm frozen? Is it something the state should pay for to ensure it's a right that everyone has? If it would avert genetic disorders, I'd say yes.

Wibbs

I would reckon 18 is more than a little scaremongering. The original studies into the rise of genetic disorders in older fathers a) found the percentage risks low and b) more importantly didn't take the ages of the mothers into account. Your average say 40 year old man is going to be having a child with a woman between the ages of 35-40 odd. The risks associated with older mothers and increase of some genetic conditions like Downs are well known with good evidence to back it up. However, even there the risks are still relatively low and indeed the risks of some conditions is actually lower in women over 35. Forty per cent lower when it comes to major congenital malformations. In any event when others looked at the stats for risks and outcomes for older men with younger women, it seems the risks for genetic problems is far more dependent on the age of the mother.

In short after the studies were looked at more closely sperm donor outfits world wide upped their age limit on donation to 45-50, which says much.

This must make some biological/evolutionary sense. Women have a window of fertility that peaks in the mid twenties and the gates close in the mid forties, men have a window of fertility that is essentially lifetime, though obviously peaks when younger and tapers down after 50 odd, but men have had children in their 80's and 90's. For some reason evolution drove men to retain fertility long after women lost theirs. Maybe it's a resource thing? Men required longer to build up resources to attract women to them, so it selected for a wider window of fertility? Whereas in early societies young women are automatically valued purely on their fertility, but men need to earn their societal value? Older women are highly valued in such societies BTW. For knowledge and the ability to bring in more food for the group than they would consume(among Aboriginal peoples, by far the best gatherers are post menopausal women. The grannies get the grub in.

The human menopause is a real outlier and head scratcher and something drove this in our evolution. Our closest rellies the chimpanzee, don't go through a menopause. Their females and males decline in fertility at the same rate. Indeed female chimps can reproduce into old age, some have kids in their fifties, whereas without IVF and science that's never happening with humans. Another odd one is that young male chimps in the prime of life prefer the older females, they seek them out, even when they're really old and grey*, pretty much the opposite to humans. IE when men become rich and powerful/famous and their potential mate choices go up, their near stereotypical tendency is to go for younger, often much younger women than them. We see this throughout history with kings and warlords and such. You can often see it in many early society type setups too, where an elder in his 50's or older has a harem of women in decreasing age after "number one wife"(who always rules the roost).





*maybe because they're still fertile and their experience is everything? Quite the few young chimp mothers lose their offspring in infancy because of inexperience.

ancapailldorcha

Yeah, I thought 18 was a big young as well. I think they chose the age when someone becomes a legal adult.

I didn't know that about chimps btw. It's a mad evolutionary switch. I wonder what the reason might be for that.

<Dons tinfoil hat> I'm wondering if a story like this has anything to do with the difficulties facing career women who want kids but whose careers suffer due to the time off required. So now the media are telling men that they must behave as if they too have a biological clock to compensate. <Hat off> I mention the above as I think it's an argument which might present itself in this sort of discussion.

Wibbs

ancapailldorcha wrote: »

<Dons tinfoil hat> I'm wondering if a story like this has anything to do with the difficulties facing career women who want kids but whose careers suffer due to the time off required. So now the media are telling men that they must behave as if they too have a biological clock to compensate. <Hat off> I mention the above as I think it's an argument which might present itself in this sort of discussion.

That had occurred to me TBH

So can I cum into an ice tray and put it in the freezer?

lizzyman

Deleted User wrote: »

So can I cum into an ice tray and put it in the freezer?

Jesus mate it was a great thread with some really fascinating and well written posts above. Do you really have to drag it down with a dumb comment the average teenager wouldn't find funny?

Wibbs

Indeed. No more of that stuff please.

Emme

Wibbs wrote: »

This must make some biological/evolutionary sense. Women have a window of fertility that peaks in the mid twenties and the gates close in the mid forties, men have a window of fertility that is essentially lifetime, though obviously peaks when younger and tapers down after 50 odd, but men have had children in their 80's and 90's. For some reason evolution drove men to retain fertility long after women lost theirs.

Maybe it's a resource thing? Men required longer to build up resources to attract women to them, so it selected for a wider window of fertility? Whereas in early societies young women are automatically valued purely on their fertility, but men need to earn their societal value? Older women are highly valued in such societies BTW. For knowledge and the ability to bring in more food for the group than they would consume(among Aboriginal peoples, by far the best gatherers are post menopausal women. The grannies get the grub in.

Perhaps men were more likely to get killed by woolly mammoths and saber toothed tigers. Later on they were more likely to get killed in battle. As for resources, I think that very early humans would have been pretty much equal genderwise. Later agricultural societies were more male dominated. In tribal and agricultural times the women would have gathered berries, nuts etc. In tribal times the men would have spiced up the diet with the odd bit of meat. Hunting meat meant being away from the camp for long periods of time so a supply of meat wasn't guaranteed. The best providers of food (and resources) were as Wibbs said, the older women.

Perhaps menopause evolved because too many men were killing themselves out hunting. Older women, having had children themselves, might have considered gathering food and caring for grandchildren a better use of their time than having more children. I'd say the grannies were fierce fighters as well - the men weren't always around to chase away the wolves and saber-toothed tigers.

Perhaps men's wider window of fertility was a way of ensuring that in dangerous times all women got a chance to reproduce (assuming monogamy wasn't a way of life in those days).

Wibbs

Could well be E. Funny enough there's a theory with some legs that suggests that pre modern humans coming along all previous humans had a more equal society, in that both men and women had much the same tasks, both would hunt and gather, rather than the gender roles division of labour we had. This was an advantage for us because it freed two groups to gather more food. It may also have had the side effect of ensuring more kids made it to adulthood as the mothers weren't off hunting leaving a skeleton crew of childminders back at base camp. Plus it's a lot easier to bring the kids with you food gathering compared to hunting where they would be a major disadvantage. There may be evidence in the bones too. IE while modern human infants and young kids remains are found, there tends to be more adults excavated, in the Neandertals the majority of individuals we have so far found have been infants and young children. They appeared to have the same reproductive turnover rate as us, but seemed to have lost so many of them when young.

Penny77

Interesting thread, has anyone gotten sperm frozen in Dublin?

Letree

Wibbs wrote: »

The human menopause is a real outlier and head scratcher and something drove this in our evolution.

If you think of the extended prehistoric family unit, older women who could not have anymore children would have been more useful for the group having time to forage for food, provide look out for danger and help mind the children of the younger women. That would provide an evolutionary advantage in that the children of the younger women would have more food, be safer and more likely to reach adulthood.

Consider on the other hand older women having yet more children in the group, aside from age and death in those times resulting in their new babies being orphaned. Those older mothers would have been less available to gather food, look out for danger etc. They would have been a drain on the extended group instead of an asset.

I'd imagine in evolutionary terms the group fared batter and raised more children to adulthood where older women couldn't have children anymore.

newport2

Wibbs wrote: »

This must make some biological/evolutionary sense. Women have a window of fertility that peaks in the mid twenties and the gates close in the mid forties, men have a window of fertility that is essentially lifetime, though obviously peaks when younger and tapers down after 50 odd, but men have had children in their 80's and 90's. For some reason evolution drove men to retain fertility long after women lost theirs.

Is it possible that evolution did not have a hand in this, ie women died before reaching the menopause anyway perhaps? The average age people lived to only reached 50 about 1900, in 1600 it was 38. Go back a few hundred years more (not to mention 1000's of years) and neither men nor women would have lived up to the point where their ability to reproduce differed from each other. If they didn't live old enough to take advantage it wouldn't have made much of a difference.

Sleepy

You're confusing life expectancy with the ages people actually lived to newport2.

There's plenty of evidence of ancient humans surviving well into their sixties and seventies. Infant mortality rates were so high, however, that life expectancy would have been much lower.

newport2

Sleepy wrote: »

You're confusing life expectancy with the ages people actually lived to newport2.

There's plenty of evidence of ancient humans surviving well into their sixties and seventies. Infant mortality rates were so high, however, that life expectancy would have been much lower.

Fair enough, but taking child mortality out of it:

"Child mortality is defined as the number of children dying before their 5th birthday. To see how life expectancy has improved without taking child mortality into account we therefore have to look at the prospects of a child who just survived their 5th birthday: In 1845 a 5-year old had a expectancy to live 55 years. Today a 5-year old can expect to live 82 years. An increase of 27 years."

http://ourworldindata.org/data/population-growth-vital-statistics/life-expectancy/

A 50% increase since 1845, when it was 55. I'd be surprised if that didn't continue to decline as you go further back, albeit not at the same rate perhaps.

While evidence exists of ancient humans surviving well into their sixties and seventies, I couldn't find anything on what proportion lived that long. Possibly not very many did and this was the exception and not the rule? Kind of like people living beyond 100 now.

This is an interesting read:

http://johnhawks.net/weblog/reviews/life_history/age-specific-mortality-lifespan-bad-science-2009.htmlhttp://johnhawks.net/weblog/reviews/life_history/age-specific-mortality-lifespan-bad-science-2009.html

Sleepy

1845 would be an interesting date to compare to as we're right at the tail end of the Industrial Revolution. I've read before that human health deteriorated rapidly over this time period (as one might expect given the working conditions and living conditions of an urban population of the time).

I'm not disagreeing that we live longer now than our ancestors did but I think there'd still have been plenty of 50+ year olds in early human groups.

Wibbs

newport2 wrote: »

Is it possible that evolution did not have a hand in this, ie women died before reaching the menopause anyway perhaps? The average age people lived to only reached 50 about 1900, in 1600 it was 38. Go back a few hundred years more (not to mention 1000's of years) and neither men nor women would have lived up to the point where their ability to reproduce differed from each other. If they didn't live old enough to take advantage it wouldn't have made much of a difference.

It seems between the fall of Rome and 1900 in Europe the longevity stats went right down across the board. Rolling plagues for centuries, climate change, wars famines etc took their toll(even so, in the middle of all that check out the ages of well known Old Masters of the Renaissance and quite a lot of them saw 70 and well beyond).

But let's say that's correct, that on average people died before their reproduction status made a difference and this selection pressure evolved the menopause that still doesn't explain the clear difference between the genders and the difference between us and the other great apes whose females stay fertile throughout life. EG Chimps can live to 60(in captivity) and the oldest known had a baby at 56. It seems at some point in human evolution something changed with us.

Emme

Wibbs wrote: »

But let's say that's correct, that on average people died before their reproduction status made a difference and this selection pressure evolved the menopause that still doesn't explain the clear difference between the genders and the difference between us and the other great apes whose females stay fertile throughout life. EG Chimps can live to 60(in captivity) and the oldest known had a baby at 56. It seems at some point in human evolution something changed with us.

Perhaps menopause in human females is a mutation which occurred after aliens spliced their DNA into apes

All jokes aside mortality in childbirth was relatively high in humans up until the 19th century and in some cases into the early 20th century. If a grandmother or other older female relative was around this would ensure the survival of the orphaned children. Human babies need a lot of care relative to other young and a grandmother would have been (and in many cases still is) a welcome extra pair of hands.

H3llR4iser

A possible reason is the extremely long time it takes a human child to reach maturity and not be constantly requiring the attention of an adult / parent.

As far as I (well, Google!) know, chimps reach sexual maturity at around 7 years of age - biologically speaking, it takes us roughly double that time. I read there are cases where chimp rely on their mother until roughly 10 years old, but it's not the norm.

Even allowing for the completely different social structure of early mankind, I'd have a though time imagining any girl or boy younger than 13/14 being completely independent; So menopause might have evolved to try and give offspring a better chance of survival - a woman's last possible pregnancy would occur when she still had enough lifetime to fully rear the child. The question at this point is why it didn't evolve equally in chimps.

Another possibility, which I feel might be a very likely one, is one of population control - we have very unique needs as a species compared to all the others, and use an astronomical amount of resources in the process compared to other animals; None of them build shelter, utensils or use clothing. An early human settlement where children were born constantly and with an exponential growth curve would lay waste on a territory and even run out of space relatively quickly.

As for why men don't lose fertility, or at least lose it in a much slower and less dramatic way, it might have something to do with the combination of need for genetic diversity, the fact the men were not as involved in child rearing in early humanity and, as many hinted, the need to prove oneself's strength and health over time. Considering that monogamy was probably never on the cards on nature's original plan for mankind, it makes sense that women in early settlements would "retry" with a different man in case a pregnancy didn't yield the expected results; In this scenario, the 50 years old strong, resilient ace hunter does represent a safer bet that the 15 years old guy who just barely stuck his nose outside the settlement, especially considering that there was no expectation for him to stay around for a long time while the children grew up.

And then there's the last possibility: IT WAS ALIENS! We're simply the result of genetic manipulation and menopause is a glitch they didn't resolve. Who knows, not too long ago people claiming we shared ancestry with chimps were regularly burnt as heretics...

silverharp

H3llR4iser wrote: »

AAnother possibility, which I feel might be a very likely one, is one of population control - we have very unique needs as a species compared to all the others, and use an astronomical amount of resources in the process compared to other animals; None of them build shelter, utensils or use clothing. An early human settlement where children were born constantly and with an exponential growth curve would lay waste on a territory and even run out of space relatively quickly.

some mutations are just random . An overlapping evolved instinct is that males and prehumen males (I guess) to be attracted to youth in females. Its as likely as not that the males wouldn't have been interested in mating with 60 or 70 year olds so the population control wouldn't have been an issue. the "grandma" hypothesis on the surface anyway seems to have a believable cause and effect in helping to nurture the following generations

H3llR4iser

silverharp wrote: »

some mutations are just random . An overlapping evolved instinct is that males and prehumen males (I guess) to be attracted to youth in females. Its as likely as not that the males wouldn't have been interested in mating with 60 or 70 year olds so the population control wouldn't have been an issue. the "grandma" hypothesis on the surface anyway seems to have a believable cause and effect in helping to nurture the following generations

True, but I think you're underestimating the selection power females of most species have when it comes to mating. While it is true that males, in this specific case men, wanted to mate with the younger and healthiest women, it is also and more importantly true that generally women selected the strongest, healthiest men of the tribe. Technically speaking, there were a few men mating with most of the women, and a lot had no chance whatsoever - just like it still happens today in the animal kingdom (I won't go into modern human sexuality since it has changed too much beyond its original goal and is also influenced by artificial factors).

All of this to say that, essentially, early human females of advanced age would likely still have had a large pool of available mates - the males the younger females "discarded". Afterall, if we go back to the chimps - older females keep mating in their older age.