Doubting Didymus

Does anyone know of any studies that deal with heritability of human psycologican tendancies in general, or with rape tendancies in particular? No doubt such studies would be fantastically difficult to control, to account for the influence of nonheritable factors, but still, are there any reliable studies out there?

It seems to me that the case for rape as an adaptation rests on the same three points that ALL adaptation theories rely on:
1) The trait must be a hypothetical reproductive benifit in the environment and the time that it is hypothesised to have arisen.
2) The trait must be heritable to a high degree of fidelity: the children produced by organisms expressing the trait must themselves have a very good chance of also expressing the same trait, as a direct result of said childs inherited makeup (that is, not a result of cultural or other nonheritabe factors).
3) Even given the above two criteria, the trait may still have a different, non adaptationist, explanation. Some evidence is neccessary to demonstrate that framing the trait as an adaptation is a better explaination than other hypotheses.

In this case, I have seen no evidence that rapists have more children than non rapists, nor that rapists behaviour is influenced by inherited 'rape genes' that are also passed on to the rapists progeny, nor, indeed, have I seen any historical or other evidence that the above two factors were at work in the past. (remember that the undisputed fact that rape has occurred in the past is not the same thing. It should be shown to be more likely that past rape tendancies were heritable and advantageous than it is that the rape tendancy is not an adaptation.)

Really this is just a long winded way of saying "I agree with pz", who also said:

This is an irrelevant aside, but can you tell me where in the cell phospholipids are formed for inclusion in the bilayer membranes? I think I have a fair idea how the membranes themselves form, but no-one I have asked has been able to tell me where, when, and under what controls the actual phospholipid molecules are synthesised, if they are synthesised at all. I know that smooth endoplasmic reticulum is the site for lipid synthesis, but what catalyses the addition of the nitrogenous head and so forth? Is the production controlled by the cell or does it run rampant regardless?

pz

Does this help?


It's definitely regulated, at the level of the activity of the synthetic enzymes. Note the acyl-coa/g3p stuff down near the lower left -- you probably remember those from the Krebs cycle. Fatty acid synthesis is tied right into the central bits of energy metabolism.

Nic Tamzek

The OP of this thread is silly. Rape is in the same class as theft, murder, and other crimes. All of them occur in other species (if you're willing to anthropomorphize quite a bit), all of them are undoubtedly influenced by biology in humans in numerous ways, but none of them can therefore be cavalierly termed "adaptations" even if they sometimes are genetically beneficial to the actor.

Having opposable thumbs, and hindlimbs modified for walking rather than climbing, are adaptations. Having blue or brown eyes is a genetically-determined trait that is (AFAIK) not an adaptation.

Crimes are just actions of individuals. Each one is an expression of natural internal drives that are universal (think of theft: it can ber motivated by hunger, greed, etc.), local conditions, the person's cultural background, judgement, etc. A particular person's actions can be quite well explained by reference to these, as anyone familiar with literature, crime investigations, etc. knows.

IMO evolutionary theory is mostly useful in this context for explaining the basic internal drives. Can it add much more to our understanding of crimes like rape? Probably, but its probably a 5 or 10 extra percent kind of thing. And certainly throwing around wild notions that rape is an adaptation, or even genetic, in the absence of any evidence for either, is not the way to increase understanding.

God Fearing Atheist

1) The sociobiological theory (adaptive or adaptive by-product) predicts that females will be the most frequent victims of sexual assaults.

Confirmation: About 9 out of every 10 victims of rape are female. (http://www.rainn.org/ncvs99.pdf).

2) The sociobiological theory predicts that reproductive-aged females will be more frequently victiminized than pre-pubesent girls and post-reproductive aged women.

Confirmation: About 62% of female rape victims are of peak reproductive age (11-29), only 6% were older, and 29% were younger (below 11). (Kilpatrick et al, 1992, Thornhill & Thornhill, 1983). Even among male-male sexual assults, offenders pefer youthful features (Perkins et al, 1996).

3) The sociobiological theory predicts that reproductive-aged females will more likely face certain types of rapes, in particular, penile-vaginal penetration.

Confirmation: More than any other rape group, the 11-29 year old category faces penile-vaginal penetration (Thornhill & Thornhill, 1991).

4) The sociobiological theory predicts that reproductive-aged females will more likely face ejaculation in their reproductive tracts during forced copulation.

Confirmation: More than any other rape group, the 11-29 year old category faces more ejaculation in their reproductive tracts. (Thornhill & Thornhill, 1991).

6) The sociobiological theory predicts that, if there are evolved counter-rape mechanisms in females, they will most clearly manifest themselves in the preceeding groups (that is, according to age, possibly fertility, type of forced copulation, and other factors like pair-bonding status, lack of female orgasm, and so forth).

Confirmation: Patterns of psychological trauma and risk-aversion correlate with age, fertilty (with risk-aversion), type of copulation, and marrital status. The vast majority of female rape victims do not reach orgasm. (Thornhill & Thornhill, 1990, 1983, 1991; Baker & Bellis, 1995).

7) The sociobiological theory predicts that, were rape adaptive or a by-product of adaptive male sexual drives, it would be common to all cultures.

Confirmation: Rape exists in all known cultures (Pamler, 1989; Jones, 1999; Rozee, 1993).

8) The sociobiological theory predicts that sexual desire is a proximate cause in most rapes, entirely or in part.

Confirmation: Almost all rapists (84%) report sexual desire as a motivation, at least in part, for their crime (Smithyman, 1978). There may also be reason to think convicted rapists (on whom these studies are done) tend to underreport sex as a primary motive so as to appear less of a threat (Symons, 1979).

9) The sociobiological theory predicts that excessive force against rape victims (that is, beyond what is instrumentally necessary to commit the act) will be rare.

Confirmation: Most rapes involve only instrumental force (threats in 84% of cases, 64% involving holding and/or pushing). A minority involve slapping (17%), beating (22%) and choking (20%) (McCahill et al, 1979).

Now, what would we expect if control/power was the ultimate cause of rape in humans? One would think we would expect a more even age, or even sex distrubtion among victims, perhaps even tilted toward older or younger individuals due to physical vulerability (Groth & Hobson, 1983, even cite this prediction despite the evidence to the contrary, as part of the theory). We would probably expect to see alot of excessive violence, even distrubitons of copulation type and ejacuation, and so forth.

Now, which makes more sense?

-GFA

notMichaelJackson

Rape is definetly not a means of reproducing; if it were, then there very few, if any, rapists would murder their victims. Murding the victim eliminates any chance of a child being produced via rape (duh). Also, children and men would not be rape victims if it were about procreation.

Rape is an act of direct violence, nothing more, nothing less.

God Fearing Atheist

See the above post on excessive force. As Greenfield (1997) reports, between 1976 and 1994, there was no year in which murder-rapes exceeded 2% of all homicides in the United States.

Women are almost universally the victims of sexual aggression.

-GFA

pz

You aren't.

Your "confirmations" aren't confirmations at all, since they seem to be general observations that are true of just about any hypothesis about why men rape, not just the sociobiological ones. You aren't evaluating tests that discriminate between competing theories.

Your claims that other theories would expect "excessive violence, even distrubitons of copulation type and ejacuation, and so forth" are straw men. Rapists are degrading their victims, and aren't trying to practice the positions from the Kama Sutra -- they're just going to ram it in wherever they like. Young women get raped because most rapists are young men, and that's who they associate with. Young men get beat up, rather than raped, because there is a strong cultural stigma against homosexual acts. Raped women aren't routinely killed, not because the rapist hopes to breed, but simply because the majority of violent acts do not lead to the death of the victim.

Your claim that women who are raped are not typically subject to "excessive violence" is a rather appalling comment. The act of rape in itself is an act of excessive violence.

Doubting Didymus

GFA, I gave you three criteria that your adaptationist theory of rape must meet in order to be plausible. Do you agree or disagree with those criteria?

lpetrich

It may be comparable to nest parasitism, which some species of birds practice. A cuckoo will lay her eggs in other birds' nests; she thus gets caretakers for her babies for free.

At least as long as those caretakers are unable to recognize cuckoo eggs; there is some evidence of an arms race between cuckoos and their victims -- those birds that are victimized by cuckoos and other nest parasites are more selective about what eggs they permit in their nests than those that are not.

Closer to our species, some male orangutans are relatively small -- and they rape female ones. This suggests that rape may be a way for social-loser males to reproduce.

Jackalope

Keep remembering that those are the reported rapes. Males are far, far less likely to report a rape than females are, simply because of the social stigma. They're also less likely to report spousal abuse by their female partners, and less likely to report sexual harassment.