I despise creationist style writing in science. I'm talking to YOU ScienceNews

[Rhea]

But the authors never meant to say that a baby is actually, consciously trying to prevent it's mother from having more children. That's absurd, the authors are aware that is absurd, and they casually used language that implied it because it is so absurd that it never occurred to them that someone might read that as the meaning.

And also directly contradicted by all the anecdotal evidence history is offering us: the more oppressed and poor (socially stressed) are some people, the more offspring they have. Regardless of how much „the little one” will cry his/her lungs out.

I would say the problems are more along the lines of ignoring that the unit of selection tends to be the gene and not the individual. Suppose there exists a "Cry so your mom will be too stressed out to have sex" gene. Suppose some babies carry this gene and it gives them a survival advantage so, oh... 80% of carriers survive to adulthood and they have an average of two siblings. That's 2.4 gene-carriers, on average.

Now consider instead the "Sleep through the night so your parents have a chance to have more sex" gene. Carriers have more siblings, and so a lower survive chance, but they have more siblings. So let's say a carrier survives to adulthood only 60% of the time and has an average of 4 siblings. That's 3.0 gene carriers, on average.

The "crying" gene is being selected against, there. The numbers would have to fall into some pretty specific ranges for it to out compete the "don't cry" gene.

If it significantly reduces the number of siblings, the crying gene is being selected against unless the survive difference is enormous. The survival difference might be enormous, but if it is there will be a multitude of reasons beyond a lack of siblings.

Interesting discussion points. Would the sibling factor be 2x? And can we compute the "break-even point" on sibling number (or spacing)?

 

[Musing Man]

OK, The Paul.

First off, there are no „authors”, there's just one dude from Harvard who has a pet theory. I've read it, and it plainly states that some kids do that for it somehow enhances one infants' survival chances.

No, it doesn't.

It may do so in some cases in our 50 to 60 years old society, Western society that is, but overall - historically and as a species it does not.

Crying out loud all night long does so much more than preventing parents to have sex - and nothing beneficial for the infant. The mother will be more stressed and will produce an inferior milk, inferior care and less affection, OK? This is „indoors” - not „out there”.
Persistence in this behavior won't bond the family; quite the contrary.
There is nothing that would prevent any of the parents to produce more siblings either outside the family or during the day.

I get what you say, but that's not what Haig (the author) says.

Crying is a survival mechanism, just not in that way...

 

[Jokodo]

Now, you may say that I'm pulling all this out of my ass, but I'm not. I do have what ”they” call ”very early memories”.

Among others, I can recall why I cried (mostly) as a baby:

During the night: For not being able to make sense of the environment, especially while lacking a familiar presence. Or for simply soiling myself and being displeased with it.
During the day: For not being able to stand up properly. And sometimes for not making my whims being met.

Even if we accept your very early memories at face value, those could still be argued to be your rationalisations and not to be informative about the ultimate causes of crying behaviour.

 

[Jokodo]

But the authors never meant to say that a baby is actually, consciously trying to prevent it's mother from having more children. That's absurd, the authors are aware that is absurd, and they casually used language that implied it because it is so absurd that it never occurred to them that someone might read that as the meaning.

And also directly contradicted by all the anecdotal evidence history is offering us: the more oppressed and poor (socially stressed) are some people, the more offspring they have. Regardless of how much „the little one” will cry his/her lungs out.

I would say the problems are more along the lines of ignoring that the unit of selection tends to be the gene and not the individual. Suppose there exists a "Cry so your mom will be too stressed out to have sex" gene. Suppose some babies carry this gene and it gives them a survival advantage so, oh... 80% of carriers survive to adulthood and they have an average of two siblings. That's 2.4 gene-carriers, on average.

Now consider instead the "Sleep through the night so your parents have a chance to have more sex" gene. Carriers have more siblings, and so a lower survive chance, but they have more siblings. So let's say a carrier survives to adulthood only 60% of the time and has an average of 4 siblings. That's 3.0 gene carriers, on average.

The "crying" gene is being selected against, there. The numbers would have to fall into some pretty specific ranges for it to out compete the "don't cry" gene.

If it significantly reduces the number of siblings, the crying gene is being selected against unless the survive difference is enormous. The survival difference might be enormous, but if it is there will be a multitude of reasons beyond a lack of siblings.

You are, of course, assuming that the siblings are sired by the same father. This need not have been the default situation through much of hominin evolution. If the siblings are by an unrelated father, relatedness drops to 1/4, if they're by your father's brother as in fraternal polyandry, it's between 5/16 and 3/8 (depending on how closely your father is related to his brother).

 

[Jokodo]

While I agree with most of what you say, let me tell you just this: ask any cop about infanticides.

I won't go in to more elaborate scenarios, such as crying babies in the wild, while fleeing from any sort of predators, including humans.

As a bonus, most (not many, but most) married couples with children have a less satisfying sex life. Not necessarily UNsatisfying, just less so. I should know, I've been there. And that's reflected in any of our mass cultural products - movies, sitcoms etc. It's not a myth, it's real.

I've been there too, and I can't confirm that sex life gets less satisfying with kids. There are ups and downs, but there were such before we had kids, and as far as I can tell other couples without kids experience similar.

Maybe that's because we're not legally married. You did say "married couples with children".

 

[Musing Man]

Maybe that's because we're not legally married. You did say "married couples with children".

Yep, I said that, and I also said what you said previously, in other words. I refuse to quote myself.

 

[The Paul]

OK, The Paul.

First off, there are no „authors”, there's just one dude from Harvard who has a pet theory. I've read it, and it plainly states that some kids do that for it somehow enhances one infants' survival chances.

No, it doesn't.

It may do so in some cases in our 50 to 60 years old society, Western society that is, but overall - historically and as a species it does not.

Crying out loud all night long does so much more than preventing parents to have sex - and nothing beneficial for the infant. The mother will be more stressed and will produce an inferior milk, inferior care and less affection, OK? This is „indoors” - not „out there”.
Persistence in this behavior won't bond the family; quite the contrary.
There is nothing that would prevent any of the parents to produce more siblings either outside the family or during the day.

I get what you say, but that's not what Haig (the author) says.

Crying is a survival mechanism, just not in that way...

If you reread the article carefully you will, in fact, discover that he specifically states there is no intention on the part of the baby to prevent its mother's pregnancy.

- - - Updated - - -

But the authors never meant to say that a baby is actually, consciously trying to prevent it's mother from having more children. That's absurd, the authors are aware that is absurd, and they casually used language that implied it because it is so absurd that it never occurred to them that someone might read that as the meaning.

And also directly contradicted by all the anecdotal evidence history is offering us: the more oppressed and poor (socially stressed) are some people, the more offspring they have. Regardless of how much „the little one” will cry his/her lungs out.

I would say the problems are more along the lines of ignoring that the unit of selection tends to be the gene and not the individual. Suppose there exists a "Cry so your mom will be too stressed out to have sex" gene. Suppose some babies carry this gene and it gives them a survival advantage so, oh... 80% of carriers survive to adulthood and they have an average of two siblings. That's 2.4 gene-carriers, on average.

Now consider instead the "Sleep through the night so your parents have a chance to have more sex" gene. Carriers have more siblings, and so a lower survive chance, but they have more siblings. So let's say a carrier survives to adulthood only 60% of the time and has an average of 4 siblings. That's 3.0 gene carriers, on average.

The "crying" gene is being selected against, there. The numbers would have to fall into some pretty specific ranges for it to out compete the "don't cry" gene.

If it significantly reduces the number of siblings, the crying gene is being selected against unless the survive difference is enormous. The survival difference might be enormous, but if it is there will be a multitude of reasons beyond a lack of siblings.

You are, of course, assuming that the siblings are sired by the same father. This need not have been the default situation through much of hominin evolution. If the siblings are by an unrelated father, relatedness drops to 1/4, if they're by your father's brother as in fraternal polyandry, it's between 5/16 and 3/8 (depending on how closely your father is related to his brother).

Oops. Good catch. That does give the numbers a little more wiggle room.

 

[Jokodo]

You are, of course, assuming that the siblings are sired by the same father. This need not have been the default situation through much of hominin evolution. If the siblings are by an unrelated father, relatedness drops to 1/4, if they're by your father's brother as in fraternal polyandry, it's between 5/16 and 3/8 (depending on how closely your father is related to his brother).

Oops. Good catch. That does give the numbers a little more wiggle room.

On second thought, your numbers don't seem to add up anyway. You seem to be assuming that if you have the gene, all of your siblings will too. That's not how it works when a new mutation spreads through a population -- there's at least a period of polymorphism until it reaches fixation, if it ever does. So your (full) siblings would have a 50% chance of carrying the gene if you do, not 100% (in a first approximation, details depending on whether it's dominant, recessive, etc.). Some siblings will carry one gene, some the other, and there's of course competition among siblings too.

So, with your numbers and still assuming full siblings, we get: <Your survival chance> + <number of siblings> * <survival chance of siblings> * <chance of sibling carrying the gene> = 0.8 + 2 * ( (0.8 + 0.6) / 2) * 0.5 = 1.5 vs. 0.6 + 4 * ( (0.8 + 0.6) / 2) * 0.5 = 2

That's still an advantage for the non-cryers, but your factor's probably much too high. After all, whether you carry the gene may affect the spacing between you and sibling 2, but not between sibling 2, 3, and 4 -- that will depend on whether siblings 2 and 3 are carriers, and that's independent of your status.

 

[The Paul]

You are, of course, assuming that the siblings are sired by the same father. This need not have been the default situation through much of hominin evolution. If the siblings are by an unrelated father, relatedness drops to 1/4, if they're by your father's brother as in fraternal polyandry, it's between 5/16 and 3/8 (depending on how closely your father is related to his brother).

Oops. Good catch. That does give the numbers a little more wiggle room.

On second thought, your numbers don't seem to add up anyway. You seem to be assuming that if you have the gene, all of your siblings will too. That's not how it works when a new mutation spreads through a population -- there's at least a period of polymorphism until it reaches fixation, if it ever does. So your (full) siblings would have a 50% chance of carrying the gene if you do, not 100% (in a first approximation, details depending on whether it's dominant, recessive, etc.). Some siblings will carry one gene, some the other, and there's of course competition among siblings too.

So, with your numbers and still assuming full siblings, we get: <Your survival chance> + <number of siblings> * <survival chance of siblings> * <chance of sibling carrying the gene> = 0.8 + 2 * ( (0.8 + 0.6) / 2) * 0.5 = 1.5 vs. 0.6 + 4 * ( (0.8 + 0.6) / 2) * 0.5 = 2

That's still an advantage for the non-cryers, but your factor's probably much too high. After all, whether you carry the gene may affect the spacing between you and sibling 2, but not between sibling 2, 3, and 4 -- that will depend on whether siblings 2 and 3 are carriers, and that's independent of your status.

Yeah, I assumed a scenario with two homogenous "crying gene" parents and two homogenous "not-crying" gene parents because I was being lazy and trying to demonstrate the general principle that a gene that harms your relatives (or, in this case, causes you to have fewer of them) while conferring some benefit to you, personally, isn't necessarily doing itself any favors.

...plus, at the heart of it, the numbers are made up. They have to be made up, because we're never going to find actual data on this kind of thing, so I didn't feel like being very careful.

You're right about my overstating the consequences of reducing your number of siblings, though.

I'd expect a crying gene influences survival significantly, not because there are fewer siblings, but because a baby that demands constant attention gets fed/cleaned more and is in better health. Something it'd be hard to pick out from the benefit of having fewer siblings.