Hmm. But while this suggests that some left-handedness is a result of brain damage, it doesn't really account for what I guess I'd call 'primary NRH'. Which as I recall seemed to be under some sort of balancing selection, resulting in improved reproductive fitness for men and reduced fitness for women at - at least based on number of grandchildren...

*sigh*

the lawyers will come out now with mitigating circumstances...though this doesn't surprise me.

A simple google gives you the old claim that 25% of the earlier astronauts were left-handed. Were they somehow damaged? I don't want to sound gauche, but how about that woman astronaut who went bonkers a week or back - is she a sex-addicted leftie?

And now pedophiles? It all seems so sinister.

My mother claimed that I was left-handed when very young but became right-handed by copying the rest of the family. Does that happen, or was she mistaken?

"the lawyers will come out now with mitigating circumstances...though this doesn't surprise me."

I've never understood why basic neurological dysfunction can be used as an excuse in a criminal trial. A defence based on "Oh, my brain makes me kill people", etc. should reasonably warrant a far longer lockup period, for reasons of public safety, than for someone who has just run into some bad luck, etc.

I assume that hope that a prison sentence to reform a man lies behind it, but the empirics on that point are pretty weak.

Ive also read that Left handers are more likely to have an IQ in the genius range. Is that true?

And isnt that, in some ways, the opposite of brain damage?

How many people here are left-handed? I am, and I've noticed that a disproportionate number of intelligent people also seem to be (I hear it is especially high among scientists).

I've also never understood why your brain was considered a mitigating circumstance rather than grounds to be kept away from society.

Pedophilia is a strange behavior not readily explainable in Darwinian terms. Maybe it could be explained by a pathogen opportunistically manipulating neural activity to facilitate transmission to an ideal host (at appropriate stage of life cycle). Humans don't want to be believe it can happen to them ("we are rational"), but it happens with other species, often in truly bizarre ways. After all, sex is an efficient way to transmit pathogens.

Hebephilia is a very different matter in Darwinian terms, especially for men. A 15 year old girl/woman is probabilistically more fertile and more apt to produce a viable offspring. "Adolescence" is the brainchild of extended education and parental responsibility for young adults in the family. Teenagers "rebel" because they are not children anymore, and their instinct is to seek non-parental role models. So I wonder how fudged those numbers are on the hebephilia (not to be confused with philosemitism) - the authors seemed to hem and haw a little around those points. As the adult husband cuckolded by a teenage rival says in "Notes on a Scandal" - nothing unusual about physically responding to a hot teenager, but we, as civilized adults, do not act on this natural impulse for the greater good (welfare of young people, integrity of family structure, and so on).

Like gender and IQ, the biological significant of adolescence is another place where nature and modern social mores diverge.

Does that happen, or was she mistaken?

yes. i know of older people who are righties who were born left, and it certainly happens in third world nations where ass wiping with the left hand is normative.

me: i am right handed for fine motor control, but often left handed for more gross actions. e.g., i write right handed, but play basketball left handed. i an switch hit (opposite field left handed, pull right handed). i can throw a football with both hands, more accuracy and touch right handed and more range left handed. my left arm is stronger, but right arm is subtler. i am the promise come!

How many people here are left-handed?

I write left-handed and throw a baseball left-handed, but bat and throw a water polo ball righty. just a freak, I suppose.

I think I might have posted this before, but here is "For the law, neuroscience changes everything and changes nothing", which I found quite good.

Dobeln said—

I've never understood why basic neurological dysfunction can be used as an excuse in a criminal trial. A defence based on "Oh, my brain makes me kill people", etc. should reasonably warrant a far longer lockup period, for reasons of public safety, than for someone who has just run into some bad luck, etc.

Couldn’t agree more. With qualifications. If a treatment could be devised that didn’t depend on the patient voluntarily staying on meds but rather say surgically changing some areas of the brain or implanting something, then that might change things somewhat. Not totally, but somewhat, depending on reliability.

It all goes back to “mens rea” (guilty mind). I remember thinking in law school that this was a crock, or at least a partial crock, for reasons such as those you refer to, and for some others. I never made a peep because, hell, first year law school is an intensely competitive and immediate post law school job critical business, and there was absolutely zero percentage in having my prof and virtually the entire rest of the class jump all over me. (Easy prey was seized in law school believe me. If I'd been black or a woman I probably could have done it.) It would be next to impossible to be seen looking smart in that deluge. I thought it was a partial crock even though I still thought of myself then as rather a lefty at heart, though also a free thinking one, and one whose journey rightward had already considerably begun.

The doctrine arouse to distinguish accidentally wrongful results from intentionally wrongful ones. As such it was seen as glorious liberalizing progress above previously heathen like simplistic vindictiveness. Then negligence comes in and so on. But it also lead to the insanity defense (also regarded as liberalizing rationalist progress separating us from more primitively emotional and UNINTELLIGENT vindictiveness). It first was sharply restricted, in part because it was recognized how corrosive an over broad doctrine could be to the justice system keeping people in line. But then it keep being loosened as our therapeutic concepts of misbehavior (Freud was a big influence) kept encroaching further into our concepts of evil behavior which should be rightfully punished.

Essentially the idea is that retribution should be no part of sentencing the insane - which the soft left wants to be ever more expansively defined. Only prevention and rehabilitation. Then the mental health professional experts who are generally assigned the task of evaluating how complete those processes have been after an initial few years of the previously indeterminate involuntary commitment has run, do so from a decidedly permissive and optimistic point of view (their work has been effective). Their viewpoint is generally far more centered on the welfare of their “patient” than the degree of safety of the society in which he/she will move post release.

In some especially media heavy cases (such as the guy who shot Reagan) they may be pretty cautious in order to keep public outcry from demanding that this whole regime be junked. But they usually aren't in less scrutinized cases. They simply aren’t professionally primed to think in terms which put much more weight on public safety. A course or two aimed in that direction does not overcome the rest of their professional training or it’s cultural mindsets.


Of course lefties of the soft human rights emphasizing variety want to do away with retribution anyway, as much as they can get away with in stages, for all criminal activity. To which I say, forget it.

Joe Blow said—

Pedophilia is a strange behavior not readily explainable in Darwinian terms.

Given all the hysteria which surrounds this topic in America today it’s not surprising that the vast majority of people wish to make overbroad statements which aren’t true – at least the overbroad parts of which aren’t.

Attraction to PRE-PUBESCENT females is at least a bit of a challenge to explain in Darwinian terms. It’s also far more unusual than what is popularly thought of as pedophilia in this country currently, or than what is defined as criminal and gets someone classified as a sex offender solely because of the age of the object of the offenders lust.

Probably most and maybe a higher percentage than that of men are physically attracted to young but post-pubescent girls, especially those who show development of secondary markers of onset of fertility, such as breasts of some noticeable size, rounding hips, etc. In others words pictures of middle teens who show signs of considerably budding sexuality can be quite erotic. Perhaps that’s part of why they as well as those of children are currently so taboo and federally illegal. They’re visually erotic to almost all men I think. Sweet sixteen is called that for a reason and not only seventeen year old boys think so.

Now actual relations, aside from the severe legal and social taboo violation penalties, is another matter entirely, considering such factors as social interaction (have nothing in common, no friends in common or potentially in common, and nothing to talk about together) and often (certainly not always except for really large age differentials) the unlikelihood of the adolescent being attracted to a considerably older man.

Further, being attracted to those who whose fertility has just blossomed and hence having a shot at being the first to inseminate her before other competition has set in, is not so hard to understand as an evolved instinct in at least a substantial number. Others (including myself) will prefer the full bloom even on an entirely physical plane (pictures or one nighters real or imagined or prostitutes), before we consider likelihood of having anything to talk about or do together besides sex. Perhaps the full bloom preference tends to go together with having a better shot in physical terms at the male competition thing for more widely prized females, while nerdier guys tend to go for younger looking females. I don’t know. Has some plausibility. Studies?

These days high nutrition, excellent health and widespread children pampering has lead to fertility onset generally by 13 and sometimes by 11. I think society tends to want to keep this knowledge from getting too broadly disseminated, but it’s out there. Even breast development is often pretty strong by 14 or even 13 (particularly among those with significant African blood).

In days when fertility usually came in later, often not until 15 or so, a great many US states had ages of marriage and sometimes consent as low as 14 and usually (never?) no higher than 16. It was primarily feminists, allied here as in some other areas with the religious who had become alarmed at unwed pregnancies and the abortions often resorted to to end them, that this was raised throughout the US in the last few decades to at least 16 and often as high as 18 (which is rather ridiculous). Sixteen and sometimes fourteen are more common ages of consent still in Europe.

So what we socially and legally define as pedophilia today is quite different from how it was more traditionally defined here and continues to be elsewhere. It’s also quite different from where our biological attraction instincts draw the line.

Dougjinn, thanks for adding your thoughts. It's kind of a puzzle actually, why American society nowadays expects nubile young women to wed (stupid, unproven and poor) young men. It's such a waste, and probably related to the indecently high divorce rates in this country. One strange hypothesis that I thought of is that credit is to blame. Young men can now access all kinds of chick-pleasing expenditures that are realistically beyond their means (nice cars, expensive dates) using credit cards.

What's amazing is how Americans are knee-jerk disgusted at the idea of "dirty old men" admiring women only five or ten years their junior. The very natural alliance of older, established men and nubile young brides has been re-cast as some kind of mental disease.

This might go back to over-protective parents and the emphasis on "peer culture" in American society. Life has become a cradle to grave kindergarten, in which mentor relationships are questioned but parents are too busy to meaningfully invest time and training in adolescents. Somewhere like even the Soviet Union, teacher-student sex was something that happened somtimes and wasn't so strongly stigmatized (certainly not with the knee-jerk outrage it elicits in the US).

Something else that occurs to me is that much of the "hebe"phobia out there comes from middle-aged women, who probably simply resent the competition from healthier and more beautiful peers. (The argument could be made that perpetually forcing women to compete in the "sexual marketplace" is anti-woman and chauvanistic, as some apologists for the Muslim veil say.)

It's still kind of a mystery to me why hebephilia is such a strong taboo in the US. Could it simply be the Lake Wobegon cult of college?

Joe Blow says:

Pedophilia is a strange behavior not readily explainable in Darwinian terms. Maybe it could be explained by a pathogen opportunistically manipulating neural activity to facilitate transmission to an ideal host (at appropriate stage of life cycle). Humans don't want to be believe it can happen to them ("we are rational"), but it happens with other species, often in truly bizarre ways. After all, sex is an efficient way to transmit pathogens.

Indeed, it does not need to be explained in Darwininan terms, but neither do we need to posit a pathogen that has such a complicated life cycle that it needs to manipulate our neural circuitry.

It seems to me that simple failure modes of a delicate piece of machinery and the presence of a pathogen that attacks certain neurons is enough to explain the phenomenon.

Joe Blow says:

Something else that occurs to me is that much of the "hebe"phobia out there comes from middle-aged women, who probably simply resent the competition from healthier and more beautiful peers. (The argument could be made that perpetually forcing women to compete in the "sexual marketplace" is anti-woman and chauvanistic, as some apologists for the Muslim veil say.)

I hope you understand that words and guilt are powerful psychological tools that can be used by some individuals to make other individuals do things that are not in the best genetic interests of those the tools are used against.

Just as there are powerful genetic conflicts of interest between mother and child, so too are there between mother and father.

I write left and throw right...right hand is strongest, left more control.

My wife was born left, parents made her use her write hand as is normal in Asia, well in the 70's.

Attraction to biologically mature females who are legally underage seems easy to understand in fitness terms. Attraction to females who are just beginning to show those signs, I can kind of see how that works--the signals look about right, sex for men is mostly low-cost if the husband/father/brothers aren't around to stick a spear in him for it, etc.

Attraction to obvious children seems at least as hard to understand as homosexuality, in evolutionary terms--you're spending substantial resources on something that can't pay off. And yet, it seems like there's a fair bit of both, today and in the historical record, with an apparently large amount of variation per culture.
It kind of seems widespread enough to make me want an explanation, though maybe "complicated machinery going slightly awry" is an answer. After all, most kinks don't have an obvious evolutionary explanation--the desire to tie someone up, or dress up like a girl, or fetishes about leather or feet or whatever, those all look plausibly like complicated machinery getting shifted off its natural purpose. Maybe that mechanism is just complicated and subject to going off the rails, like the immune system or the endocrine system.

What about sex with chickens?

Can I get a chicken nugget?

My brothers are identical twins. One is a leftie and the other right handed. My sister and I are lefties - as was our father (who was forced at gunpoint to convert to rightism as a child).

I've read before that lefties have a slightly shorter life span - but thought it mainly due to the frustrations of trying to make do in a right handed world.

BTW, I really pretty much divide different tasks to different hands. I use right handed scissors. I doubt I could work a mouse left handed. I shoot a hand gun right handed (but a rifle left handed).

I write and eat with my left hand. I throw with my right hand. (I am also right-handed for most sports)

" Hebephilia is a very different matter in Darwinian terms, especially for men. A 15 year old girl/woman is probabilistically more fertile and more apt to produce a viable offspring. "Adolescence" is the brainchild of extended education and parental responsibility for young adults in the family."
I was reading about a case in Pakistan of a 14 year old village girl married against her wishes, and experiencing a difficult pregnancy. She told her mother, "this thing (fetus) will kill me." Her mother tried to encourage her with, "all women go through this, etc." The girl knew better, even as an illiterate villager. She said, "Umma, I'm not a woman. I'm a girl." She died shortly afterwards.
I like the latest science and genetics, but sometimes gnxp is just like opening up a musty closet. All real enough, but so freakin' old. Mr. Blow, your time would be better spent surfing the web for the latest blossoms on offer from Thailand and Moravia. I can't speak for all of womankind, but the keenest -- and most startling and unexpected -- emotion most of us feel in middle age, is relief. Suddenly you feel autonomous, capable of doing things and not caring what people think. As if you belong to yourself again, the way you did before you became a--a "hebe!" (I thought that was an anti-semitic epithet, I had no idea...but I digress.) Sure, the male lust may not be there--but just now I'm thinking, whew--who the hell cares? I actually feel kind of sorry young girls and icky lusters. What a drag that life is from where I am now. .
However, it is not your "hebephilia" which provokes this missive. Consenting ADULTS and all that jazz (btw, did you know your mind at 15?) as long as you use birth control.
My point is that you are wrong about the "adolescents" reproductive "fitness." The sex that does the heavy lifting in this one area of life, reproduction, is the one that really should call the shots about how optimum all that is.
Fifteen (much less younger) is NOT the optimum age for the survival of either the mother or the baby. 20-25 is a more reasonable age for optimum mental and physical reproductive readiness in a female. Adolescence is for getting to know your new body and your new mind, and that of the opposite sex.

In the old days, and even now in 3rd world countries, mortality is particularly high for adolescent mothers and their babies. If they do survive, fistulas and other traumas are common. There are whole hospitals in places like Africa devoted to repairing these girls of "optimum age."
While I am sure everyone has anecdotes of teenage mothers who are doing just fine and dandy, stories of very young mothers always chilled me--a ghastly irony of Mother Nature. It's something you have to see to appreciate. Even the ancient Hebrew law makers had laws against sex with eleven year old girls because they might become pregnant and die. Really--that's in the Talmud. I am not sure if 12 year olds were more likely to survive statistically. Men. They try in their way.
Adolescents make terrible mothers. They are barely formed physically (inside no matter how they look outside) and mentally. One scientist writing on psychopathy and violent offenders noted the high numbers of teenage mothers of these psychos. Even in less extreme cases he cited studies showing that adolescent mothers have a "flattening" effect on their babies. They are simply not developed enough to think of babies as anything but a thing that causes them trouble. At this stage, people are meant to get used to their bodies first before undertaking the most rigorous life changing event that could happen to them.
With modern medicine, even a man could survive childbirth. But, when you think about the enthusiastic promotion of extremely young brides down through the ages (10-13 was ideal in India for example), "Hebephilia" (new word for me) has probably been responsible for more premature female deaths (and male if you include 50% of the babies) than any other one cause.

Rates of left-handedness is somewhere b/w 10-15%.

My mother claimed that I was left-handed when very young but became right-handed by copying the rest of the family. Does that happen, or was she mistaken?

It can happen, but you can see whether this affects the numbers or not. I.e., if there are fewer lefties as age increases, that could just mean that lefties are converting to righties -- but that would imply an increase in righties. If there is no increase in righties, it means lefties are dying off -- which was the case in the Dutch study.

Ive also read that Left handers are more likely to have an IQ in the genius range. Is that true?

What I've read doesn't say -- if so, could just reflect covariance with male sex (males are more likely to get screwed up by the environment). It won't do to look at mathematicians, chess players, etc. like some have -- these require not just IQ but certain personality profiles to succeed. If having a brain disturbance leads to a more eccentric personality, but left IQ alone (remember, these are probabilistic things, and the correlation between the outcomes is significant but not strong -- .1-.2 maybe), then you could get a weirdo genius type. So you'd want to look at high-IQ people who are straight as an arrow... senior partners at law firms, top surgeons, maybe?

You could just poll for handedness among the tenured faculty at the top 10 schools of law, medicine, and business/management on the one hand (no pun intended), and the top 10 schools of mathematics, music composition, and painting/sculpture/architecture on the other. They're roughly equal in IQ, but vary markedly in modal personality profiles. I'd predict the latter would show significantly more non-righties, indicating more lefties / more wacko personality, not more lefties / more IQ (i.e., if they didn't differ in handedness).

Another thing to keep in mind -- showing that X is more common among geniuses doesn't tell you that much. Evolution seeks to maximize reproductive success, not necessarily creative or High Culture success. So first you'd have to show that they had more kids than expectation. But since many variables interact to produce a genius, you wouldn't know which one or ones was/were responsible. You'd have to compare them with a group like lawyers to see if it was IQ, or street musicians to see if it was artistry.

Rosey says:

The sex that does the heavy lifting in this one area of life, reproduction, is the one that really should call the shots about how optimum all that is.

Unfortunately, the world is more complex than this simplistic view presents.

I agree that attraction to girls who are under 18, but show signs of physical maturation, is not difficult to explain in evolutionary terms. There is no reason why natural selection should have established some artificial age cutoff that agrees with our modern social definition of age of consent. The optimal age of reproductive readiness may be later, but genes will not select solely the optimum--they will select enough variance around that optimum that men will have a chance of actually finding a partner.

I have mentioned the "complicated mechanism gone awry" theory in several discussions of sexual preferences before. I think it is very plausible, given the fact that the machinery DOES have to be very compleex to take into account the complicated fitness landscape of partner selection.

Also, it's interesting that in talking about handedness, it seems nobody here has mentioned the research relating it to either cerebral lateralization of function or hormone levels. I don't have time right now to find a reference, but if you search you should be able to find lots of information on these correlations, which seem to be a simpler cause of association between mental function and handedness than a hypothetical pathogen (not to say there aren't pathogens that can influence all of these things).

The Real Richard Sharpe--

20-25 is a more reasonable age for optimum mental and physical reproductive readiness in a female.

And I think most guys of a wide variety of ages themselves regard that age range, or actually the entire 20’s as, when females tend to look physically hottest.

Which isn't to say they are actually likely to make the best mates for men a LOT older than that even if those males are high status and resource enough to attract within that range. Lots of folly that we endlessly tell stories about revolves around much older but rich/ high status men who refuse to get that message, the sort of 20's women that is attracted to such men, and the nearly inevitable results.

There are as always exceptions. Drew Barrymore was probably hotter in Poison Ivy at probably 17 than she has been since or anyway than she was five or ten years later. In fact one of the conceits of the movie is that she could go from looking like an adolescent, albeit a pretty developed one, to a stunning late twenties looking woman, depending on how she dressed and got herself up. But there are not many more precocious adolescents than she was, in bad as well as good ways.

My point in an earlier post a ways up above about most men being physically attracted to middle (16) and up teen girls was not to say that most are the most physically attracted to that age range. It was to say it’s a bit absurd to claim that attraction to at least older looking girls within that age range is something a guy in question “just can’t understand at all”. I say that’s plain BS, aka lying for social approval, pure and simple.

Attraction to female prepubescent children is another matter entirely, and I strongly suspect it is far less common than is currently imagined because we often lump with it all socially and legally forbidden attractions to any teen below the age of consent which is now often 18.

rosey said ===I was reading about a case in Pakistan of a 14 year old village girl married against her wishes===

thats sad when that happens. presumably she wld have been ok if she & her husband knew about oral sex & masturbation. anyway, 16 or 17 years is currently the optimum age for childbirth, according to midwives i know.

the, woman don't know their own minds until they are at least 36 & have a phd has worn a little thin for me..

The Real Richard Sharpe--

20-25 is a more reasonable age for optimum mental and physical reproductive readiness in a female.

Actually, I didn't say that, I only quoted it from Rosey, but must have screwed up or something.

While I think that is the optimum in many ways, evolution doesn't try to find the optimum, and some people are going to biased towards grabbing the first passable mate available, others towards waiting, and so forth ... that is, there will be a distribution.

Rosey—

I can't speak for all of womankind, but the keenest -- and most startling and unexpected -- emotion most of us feel in middle age, is relief. Suddenly you feel autonomous, capable of doing things and not caring what people think. As if you belong to yourself again, the way you did before you became a--a "hebe!" (I thought that was an anti-semitic epithet, I had no idea...but I digress.) Sure, the male lust may not be there--but just now I'm thinking, whew--who the hell cares? I actually feel kind of sorry young girls and icky lusters. What a drag that life is from where I am now.

Joan Sewell has I think written just the book for you I'd Rather Eat Chocolate, discussed in the current Atlantic Monthly in a free access article.

Re: Evolutionary explanations of pedophilia:

1) Kin altruism theory

This works especially well for pedophiles attracted to exclusively prepubescent girls (or boys, for that matter). A family with more non-reproductive members will have more resources for the children of the members who do have children, especially if the non-reproductive members have a special interest (i.e. attraction) in those children. The recessive pedophilic genes are thus passed obliquely through the reproductive relatives' children.

2) "First come, first served"

If a man can obtain a female as a mate before she has reached reproductive maturity, he will be certain to be the first one with any chance of impregnating her. This explanation is especially good for those who have a primary attraction to prepubescent and pubescent girls.

You see, it isn't that hard. It just takes a bit of non-biased imagination. You know, the kind that doesn't see bizzare pathologies in common sexual attractions.

Zygal:

I don't see how (1) can make any sense in evolutionary terms. Pedophilia that doesn't kill the victims probably reduces their fitness (by screwing them up a bit mentally), but doesn't prevent them reproducing when they're old enough. It certainly does expend the pedophile's energies on reproductively unproductive stuff. Besides that, the general strategy doesn't make much sense--kin selection usually works in the opposite direction, except in pretty specialized cases (like infanticide for sickly babies or babies spaced too closely together for the mom to carry).

(2) makes some sense as an edge case, I think--it probably explains some of why youth and innocence in women is appealing. But genes that cause you to focus much of your reproductive energies on girls who are too young to have kids that survive are going to be outcompeted by genes that cause you to focus on girls who can have kids. You get the pure 12 year old girl, she's surely a virgin and carrying no STDs, but none of your genes propogate because she dies in childbirth at 13. I get the 17 year old and risk getting a girl who's been around a bit, but she can actually have babies without advanced medical technology. Which of us has more offspring?

Most of the problems in Zygal's silly suggestions map to similar problems in adaptive explanations of obligate male homosexuality.

1) Kin altruism theory

Produce even suggestive or anecdotal evidence that pedophiles forgo all other worldly pursuits in order to raise their nephews & nieces, whom they're sexually attracted to. If you do the simple math, pedophiles would have to have twice the psychological attachment to and invest twice the amount of resources in their nieces & nephews as a mother would in her own child, just to break even. Think about that: twice as much as a mother invests in her child. Obviously pedophiles do no such thing.

especially if the non-reproductive members have a special interest (i.e. attraction) in those children

By your hypothesis, then, biological parents should be sexually attracted to their own children, the better to motivate them to invest in & care for their children. Again, obviously false. And even if this dynamic selectively applied to just the uncles, you'd still be wrong: sexual attraction is fleeting, while parental love is close to unconditional. Thus, pedophiles would invest less than a biological parent, the former's interest evaporating once the kid turned 13 (or whatever).

I'd have to think hard to remember reading a more idiotic evolutionary hypothesis, to be frank.

2) "First come, first served"

This is only slightly less loony. Recall that we're talking about people who are primarily attracted to prepubescents -- there's no "first come, first served" there. Pubescents, perhaps. But pedophiles would lose interest once their mate actually matured sexually, and was later able to bear healthy offspring, so they won't be interested in ever being "served" in a way that will produce children.

So, again, produce evidence that pedophiles not only have sex with those incapable of bearing children, but keep them around until they sexually mature, up through their late teens / early 20s, when their offspring would be most healthy. Obviously, they cut them loose once they look mature.

Even if they did do this -- which they don't -- there's a much easier solution to making sure your mate isn't sneaking around with other guys: a bias against investing in a relationship with a promiscuous woman, combined with an instinct for jealousy and "mate-guarding" once in a long-term relationship. This has the neat side-effect of not having to wait 8-10 years into the relationship to start having kids.

In general, it's easy to imagine, so that's not very interesting per se. It's more difficult to model reality, which means that is interesting. Your proposals have no grounding in the facts of the real world, indeed your empirical predictions are contradicted by them, so we can easily dismiss your imagination.

Do I not recall that in say, ancient Rome girls got married a young ages to men who were much older?

We don't know how hebephilic men in a "relationship" would progress without interference. It might be that they fall in love and continue to be sexually attracted to the person into her middle age.

agnostic: I think I was getting a much wackier theory from that than you were. Just "pedophiles spend resources caring for children instead of reproducing" is silly, but not as bizarre as "pedophiles take some of their relatives out of the reproductive pool to ensure the rest have sufficient resources to succeed."