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For those who are skeptical consider this. Human females (and males) are reproductively capable at 15 and yet who would consider them mature and capable parent

For those who are skeptical consider this. Human females (and males) are reproductively capable at 15 and yet who would consider them mature and capable parents at that age? On the other hand women have a difficult and increasingly difficult time getting pregnant from late 30's onward. And yet most women of that age would be very capable parents. What is the evolutionary explanation that the optimal physical age of reproduction is so skewed compared the optimal emotional age of reproduction? It just doesn't make sense unless young parents are not the primary caregivers to their children.

Erik816 10y ago
Consider that modern life is very different from the vast majority of evolutionary history that framed how we developed. In a modern, affluent society, a 50 year old woman would have little problem successfully raising a newborn. On the African Savanah, would that same 50 year old woman do just as well? Or would she on average find that she could not raise her children as well as the 20 year old mothers? I'm guessing the latter. Life was not as easy and it was likely much shorter on average. In a more primitive society, if a newborn's mother dies, that newborn probably has very low survival odds. Older women could definitely still have played an important role in raising children in the context of the family/tribe, but I see clear evolutionary advantages to having your children while younger, because you are simply more likely to be alive to raise them.
- LionessLover 10y ago
  > it was likely much shorter on average The average includes a huge number of deaths of children and of mothers though - not counting those risks (childhood, especially the very early one, and giving birth) it's higher than most people think. In a lecture on microbes (http://www.gresham.ac.uk/lectures-and-events/return-of-the-microbes-how-infections-are-once-more-taking-over http://www.gresham.ac.uk/lectures-and-events/return-of-the-m...) the professor mentions as an aside that a late Victorian British citizen after excluding those risks actually had a slightly longer life-expectancy than a modern British citizen! While that is fairly recent it still is long before modern medicine and antibiotics. Quote: > And what is interesting, if you take out the childhood mortality, the Victorian person between 1850 and 1880 lived slightly longer, if he was a male, than you do today. ("if he was male": giving birth was very risky) So it seems that good food (variety plus enough of it) and hygiene did most of the job of extending life-expectancy outside the above two risks - and modern medicine very significantly lowered childhood and birth (mother) deaths. In the light of such evidence modern medicine does not seem to have had a great effect on life expectancy once you made it past childhood. We can't do anything against "aging".
  - Erik816 10y ago
    I am talking about 2 million years ago, not 2 hundred.
- deleted 10y ago
  [deleted]
- kiliantics 10y ago
  Yeah, life was not that easy for these people in some sense. (I'd argue it was easier in others - no debt, no stress, no health problems stemming from sedentary lifestyles.) A 20 year old woman was much more capable of hunting than a 50 year old. Therefore, the 50 year olds were probably left back at camp with the children while the younger women and men went hunting. There is plenty anthropological research on the social structures of these hunter-gatherer humans and children were usually collectively raised by the whole group rather than in their biological families.
partycoder 10y ago
Technically speaking females are fertile before that. Then, humans are much more fragile compared to other species after birth and require extra care. This is because as the head volume increased, they had to be born ahead of time otherwise they couldn't make it through the "birth canal". Now, anatomically modern humans do not differ much from humans over 10,000 years ago. Parenting back then was basically bring food and keep predators away, not studying and getting higher education and getting a job to provide to your family. Modern lifestyle doesn't have to do much with what is good biologically: oocyte quality peaks on early 20s and decreases with age.
oh_sigh 10y ago
Or it's as simple as the fact that modern society treats people as children well into their 20s. Would I take a 15 year old american high school girl/boy as a mother/father? No. Would I take a 15 year old girl in a tribal village as mother? Sure, why not?
- raldi 10y ago
  What you're not considering is that the tribal mother is almost certainly not raising the child in a nuclear family.
  - SolarNet 10y ago
    Probably has a few grandparents around...
  - cylinder 10y ago
    The "nuclear family" is a modern construct. That's the point. What's more strange, having grandparents raise children or importing young women from across the planet and paying them to do it while the parents sit inside offices all day shuffling paper around...
cloudjacker 10y ago
The reason I'm skeptical is because this article assumes our social constructs have meaning. It also assumes that these constructs are the more favorable outcome in increasing mankind's "fitness", than a mutation that gives women more than 400 eggs. It explains this away by saying evolution perfectly timed menstruation to allow for raising the last child to adulthood coinciding with your average-est old age of 70. It must be further hypothesized and explained how natural selection could have codified this time traveling foresight into the genome, before even beginning to leap to that conclusion, while simultaneously acknowledging other mammals don't have this "feature", while simultaneously acknowledging that kidneys don't just give out at age 45 in a kidney menopause process, or lungs, or other organs. The article inadvertently makes the greatest case that the reproductive system breaking itself is a flaw, and tries to extrapolate why that would it is a feature, and why it is the best possible feature, when a best possible feature according to their time traveling genome theory, would be an adaptive amount of eggs in each woman based on their genetic fitness, instead of 400.
- a_bonobo 10y ago
  There is actually a bit of (wonky) evidence that humans and mice carry stem cells in their ovaries to indefinitely produce eggs. See for example: http://www.nature.com/news/reproductive-biology-fertile-mind-1.11805 http://www.nature.com/news/reproductive-biology-fertile-mind... > in 2009, Ji Wu at Shanghai Jiao Tong University in China and her colleagues reported that they had isolated from mice what she called “female germline stem cells” — not from bone marrow, but from ovarian tissue. When her team transplanted the cells into chemotherapy-treated female mice, they developed into mature oocytes, then fertilizable eggs and, the clincher, healthy pups. >[Tilly] has since published a parade of headline-grabbing papers, culminating this year in a report2 that he had isolated the elusive stem cells from human ovaries and coaxed them to develop into bona fide oocytes. But his work has been dogged by doubt. It's still really messy and I haven't heard anything new in 3 years, but humans may have the capability in place to create unlimited oocytes like sperm, it's just hard to tell why we don't (the OP's story is one story - there are unlimited possible stories, including simply random loss).
  - 10y ago
sjclemmy 10y ago
How long doesn't parenting last? 15~20 years? When is the emotional maturity required? When the child is a teenager, not as a baby.
cabalamat 10y ago
> Human females (and males) are reproductively capable at 15 and yet who would consider them mature and capable parents at that age? Evolution would.

Erik816 10y ago

Consider that modern life is very different from the vast majority of evolutionary history that framed how we developed. In a modern, affluent society, a 50 year old woman would have little problem successfully raising a newborn. On the African Savanah, would that same 50 year old woman do just as well? Or would she on average find that she could not raise her children as well as the 20 year old mothers? I'm guessing the latter. Life was not as easy and it was likely much shorter on average. In a more primitive society, if a newborn's mother dies, that newborn probably has very low survival odds. Older women could definitely still have played an important role in raising children in the context of the family/tribe, but I see clear evolutionary advantages to having your children while younger, because you are simply more likely to be alive to raise them.

LionessLover 10y ago
> it was likely much shorter on average The average includes a huge number of deaths of children and of mothers though - not counting those risks (childhood, especially the very early one, and giving birth) it's higher than most people think. In a lecture on microbes (http://www.gresham.ac.uk/lectures-and-events/return-of-the-microbes-how-infections-are-once-more-taking-over http://www.gresham.ac.uk/lectures-and-events/return-of-the-m...) the professor mentions as an aside that a late Victorian British citizen after excluding those risks actually had a slightly longer life-expectancy than a modern British citizen! While that is fairly recent it still is long before modern medicine and antibiotics. Quote: > And what is interesting, if you take out the childhood mortality, the Victorian person between 1850 and 1880 lived slightly longer, if he was a male, than you do today. ("if he was male": giving birth was very risky) So it seems that good food (variety plus enough of it) and hygiene did most of the job of extending life-expectancy outside the above two risks - and modern medicine very significantly lowered childhood and birth (mother) deaths. In the light of such evidence modern medicine does not seem to have had a great effect on life expectancy once you made it past childhood. We can't do anything against "aging".
- Erik816 10y ago
  I am talking about 2 million years ago, not 2 hundred.
deleted 10y ago
[deleted]
kiliantics 10y ago
Yeah, life was not that easy for these people in some sense. (I'd argue it was easier in others - no debt, no stress, no health problems stemming from sedentary lifestyles.) A 20 year old woman was much more capable of hunting than a 50 year old. Therefore, the 50 year olds were probably left back at camp with the children while the younger women and men went hunting. There is plenty anthropological research on the social structures of these hunter-gatherer humans and children were usually collectively raised by the whole group rather than in their biological families.

partycoder 10y ago

Technically speaking females are fertile before that. Then, humans are much more fragile compared to other species after birth and require extra care. This is because as the head volume increased, they had to be born ahead of time otherwise they couldn't make it through the "birth canal". Now, anatomically modern humans do not differ much from humans over 10,000 years ago. Parenting back then was basically bring food and keep predators away, not studying and getting higher education and getting a job to provide to your family. Modern lifestyle doesn't have to do much with what is good biologically: oocyte quality peaks on early 20s and decreases with age.

oh_sigh 10y ago

Or it's as simple as the fact that modern society treats people as children well into their 20s. Would I take a 15 year old american high school girl/boy as a mother/father? No. Would I take a 15 year old girl in a tribal village as mother? Sure, why not?

raldi 10y ago
What you're not considering is that the tribal mother is almost certainly not raising the child in a nuclear family.
- SolarNet 10y ago
  Probably has a few grandparents around...
- cylinder 10y ago
  The "nuclear family" is a modern construct. That's the point. What's more strange, having grandparents raise children or importing young women from across the planet and paying them to do it while the parents sit inside offices all day shuffling paper around...

cloudjacker 10y ago

The reason I'm skeptical is because this article assumes our social constructs have meaning. It also assumes that these constructs are the more favorable outcome in increasing mankind's "fitness", than a mutation that gives women more than 400 eggs. It explains this away by saying evolution perfectly timed menstruation to allow for raising the last child to adulthood coinciding with your average-est old age of 70. It must be further hypothesized and explained how natural selection could have codified this time traveling foresight into the genome, before even beginning to leap to that conclusion, while simultaneously acknowledging other mammals don't have this "feature", while simultaneously acknowledging that kidneys don't just give out at age 45 in a kidney menopause process, or lungs, or other organs. The article inadvertently makes the greatest case that the reproductive system breaking itself is a flaw, and tries to extrapolate why that would it is a feature, and why it is the best possible feature, when a best possible feature according to their time traveling genome theory, would be an adaptive amount of eggs in each woman based on their genetic fitness, instead of 400.

a_bonobo 10y ago
There is actually a bit of (wonky) evidence that humans and mice carry stem cells in their ovaries to indefinitely produce eggs. See for example: http://www.nature.com/news/reproductive-biology-fertile-mind-1.11805 http://www.nature.com/news/reproductive-biology-fertile-mind... > in 2009, Ji Wu at Shanghai Jiao Tong University in China and her colleagues reported that they had isolated from mice what she called “female germline stem cells” — not from bone marrow, but from ovarian tissue. When her team transplanted the cells into chemotherapy-treated female mice, they developed into mature oocytes, then fertilizable eggs and, the clincher, healthy pups. >[Tilly] has since published a parade of headline-grabbing papers, culminating this year in a report2 that he had isolated the elusive stem cells from human ovaries and coaxed them to develop into bona fide oocytes. But his work has been dogged by doubt. It's still really messy and I haven't heard anything new in 3 years, but humans may have the capability in place to create unlimited oocytes like sperm, it's just hard to tell why we don't (the OP's story is one story - there are unlimited possible stories, including simply random loss).
- 10y ago

sjclemmy 10y ago

How long doesn't parenting last? 15~20 years? When is the emotional maturity required? When the child is a teenager, not as a baby.

cabalamat 10y ago

> Human females (and males) are reproductively capable at 15 and yet who would consider them mature and capable parents at that age? Evolution would.