The canary in the coal mine?

Magazine rack in a Japanese store (Wikicommons - Corpse Reviver)

Hugh Hefner's death has ended an era that actually ended around the turn of the millennium. Gone are the days of porn in limited supply. During my teen years Playboy wasn’t sold in my town. You had to go to a drugstore 15 kilometers away and buy it in person, while hoping the cashier wouldn't blab to others. Then you had to find a place to hide it. Videocassettes were starting to come on market, but they had to be bought even farther away, and there was still the problem of finding a hiding place.

Fast-forward to the year 2017. From my computer I can access porn of almost any description in almost any quantity. And the access is fast, free, and anonymous. There is no comparison to the world of my youth, and even less to the world of 1953, when Playboy made its debut. That same year King Farouk of Egypt was described as a "self-indulgent playboy" with "carloads of erotica" (Gunther, 1953, p. 205). Carloads? That's nothing. Today, anyone with an Internet connection can stash away thousands upon thousands of erotic images.

This is a new sensory environment for humans. An analogy would be the increasing availability of food to native peoples in the far north. In the past their environment offered meat in limited amounts, and sometimes none was available. Hunters were thus highly motivated to seek out food and not let any go uneaten. Now fast-forward to the present. High-calorie snacks are available in any store, and they’re tasty with lots of salt, sugar, and fat—the very nutrients that were once in short supply. As a result, obesity is reaching epidemic proportions in the North.

No surprise really. And should we be surprised to learn that the increasing availability of porn today may have similarly adverse effects?

This question was addressed by a recent study on how porn consumption affects the male brain. Sixty-four men had their brains scanned, and the results were compared with the number of hours they spent viewing pornography per week. The results? Prolonged exposure to porn seemed to atrophy those portions of the brain that process erotic stimuli. The volume of gray matter was smaller in those subjects who viewed the most porn, and functional connectivity was likewise reduced. They seemed to require more porn (or harder porn) to achieve the same stimulation.

Taken together, one may be tempted to assume that the frequent brain activation caused by pornography exposure might lead to wearing and downregulation of the underlying brain structure, as well as function, and a higher need for external stimulation of the reward system and a tendency to search for novel and more extreme sexual material. This hypothesized self-perpetuating process could be interpreted in light of proposed mechanisms in drug addiction where individuals with lower striatal dopamine receptor availability are assumed to medicate themselves with drugs (Kühn and Gallinat 2014)

This interpretation is supported by a recent review of the literature:

Some internet activities, because of their power to deliver unending stimulation (and activation of the reward system), are thought to constitute supernormal stimuli, which helps to explain why users whose brains manifest addiction-related changes get caught in their pathological pursuit. [...] In short, generalized internet chronic overuse is highly stimulating. It recruits our natural reward system, but potentially activates it at higher levels than the levels of activation our ancestors typically encountered as our brains evolved, making it liable to switch into an addictive mode.

[...] previously established brain maps for "natural" sexuality cannot compare to the newly developed and continuously reinforced maps generated by continued compulsive watching of Internet pornography, and thus the addicted individual progresses to more explicit and graphic Internet pornography in order to maintain the higher level of excitement. (Love et al. 2015)

Of course, the arrow of causality might point the other way. Perhaps a man will seek out and view more porn if he already has less of the gray matter for sexual arousal. Only a longitudinal study can tell us which is causing what.

Let's suppose the first explanation is the right one. What can we do? Frankly, I'm pessimistic about legislative solutions. Give politicians the power to ban Internet porn (or Islamist extremism), and they'll use it to ban … the Alt-Right. Our political class lives in another age and sees reality through the lens of yesterday's issues and yesterday's priorities.

A second problem is that politicians try to ban child porn much more than the adult stuff. This is a classic case of going after a soft target that is secondarily important and perhaps not important at all. If porn has a desensitizing effect, it should cause pedophiles to lose interest in real children and focus on electronic images, since only the latter can be viewed in sufficient quantity to cause sexual arousal. So what’s the problem?

We should worry more about porn desensitization that disrupts relationships between adult men and women. A similar phenomenon has been noted with TV viewing: the more people watch TV, especially programming with romantic content, the more dissatisfied they feel with their marriages (Reizer and Hetsroni 2014). We may be becoming too good at creating virtual alternatives to reality.

The Japanese case

This desensitization may be most acute in Japan. In comparison to the United States, porn is more freely available there and less "compartmentalized":

Nudity is evident in both sexually identified and general circulation magazines. For instance, the weekly general-interest magazines will often include several photographs of nude women (plus ratings of local massage parlors). Although such magazines are oriented predominantly for businessmen, the inclusion of sexual photographs is also assumed to interest the business audience. In this regard, it is apparent that rigid boundaries do not exist for the publication of sexual material. In fact, nudity or sexual themes appear in Japanese teen magazines, sports magazines, fashion magazines, and so on. 

[...] Japanese public television is also different from its American counterpart. Overtly sexual material and nudity are permissible. For example, a Japanese television program known as the 11 P.M. Show can feature a strip tease, bare breasts and buttocks, reportage on massage parlors, expert authorities on sex, and so on. Similarly, the Japanese public-access movie channels can feature R-rated movies such as Emmanuelle (with some air-brushing). Finally, even Japanese commercials and advertisements have more flexibility in sexual content. (Abramson and Hayashi 2014, p. 179)

This ubiquitous porn is viewed by Japanese men, who are less polygynous than most human males and have lower blood levels of 5a-reductase—the enzyme that converts testosterone into the more physiologically active DHT (Ross et al. 1992). Lower testosterone activity seems to be an adaptation to monogamy and high paternal investment:

Numerous studies reveal a negative correlation between testosterone concentration and paternal care in diverse mammals including nonhuman primates and humans. Several researchers suggest that spousal investment accounts for the lower testosterone of married men compared to unmarried men, but findings that the lowest testosterone levels are observed in married men with children implicate paternal care as particularly relevant. Thus testosterone reduction may reflect a facultative shift in male reproductive strategy from intrasexual competition and copulation to care of young. (Shur et al. 2008)

Some Japanese authors have reached this sort of conclusion, seemingly echoing J. Philippe Rushton (although the book in question predates his publications by several years):

Finally, a number of Japanese authors (e.g., Komatsu, 1974) have also suggested that Asian populations are less sexualized than Caucasian or black populations. They cite secondary sex characteristics (less public hair, smaller breasts, etc.) as evidence. Unfortunately, the data on sexual frequencies (intercourse, etc.) are not particularly reliable, and it is not clear whether competing responses (such as nurturance) are mediating sexual expression. (Abramson and Hayashi 2014, p. 182)

Japanese men and women may thus be especially vulnerable to porn consumption. More and more couples no longer have sex, the percentage rising from 31.9% in 2004 to 36.5% in 2008 and to 47.2% in 2016 (McCurry 2017; Moriki 2012). The major reasons given are "tired from work," abstention from sex after a birth, and "sex is too troublesome" (Moriki 2012). These reasons are probably proximal, and in any case it is far from clear why they would be growing in importance.

There is some indication that the Japanese realize that porn is becoming a problem. But it’s not clear where this realization will lead. In this, as in many other things, they follow the lead of other Western countries, especially the United States. Concern about porn is thus limited to child porn.

References

Abramson, P.R. and H. Hayashi. (1984). Pornography in Japan: Cross-cultural and theoretical considerations, in N.M. Malamuth and E. Donnerstein (eds) Pornography and Sexual Aggression, pp. 173-184, Orlando: Academic Press.

https://books.google.ca/books?id=p1KLBQAAQBAJ&printsec=frontcover&hl=fr&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false

Gunther, J. (1953). Inside Africa, New York: Harper & Brothers.

Kühn, S. and J. Gallinat. (2014). Brain structure and functional connectivity associated with pornography consumption. The brain on porn, JAMA Psychiatry, 71(7), 827-834. http://jamanetwork.com/journals/jamapsychiatry/fullarticle/1874574?=

Love, T., C. Laier, M. Brand, L. Hatch, and R. Hajela. (2015). Neuroscience of Internet pornography addiction: a review and update, Behavioral Sciences, 5(3), 388-433.

http://www.mdpi.com/2076-328X/5/3/388/htm

McCurry, J. (2017). Record numbers of couples living in sexless marriages in Japan, says report, The Guardian, February 14

https://www.theguardian.com/world/2017/feb/14/record-numbers-of-couples-living-in-sexless-marriages-in-japan-says-report

Moriki, Y. (2012). Mothering, co-sleeping, and sexless marriages: implications for the Japanese population structure, The Journal of Social Science, 74, 27-45.

https://icu.repo.nii.ac.jp/?action=repository_action_common_download&item_id=1542&item_no=1&attribute_id=18&file_no=1  
Reizer, A. and A. Hetsroni (2014). Media exposure and romantic relationship quality: A slippery slope? Psychological Reports, 114(1), 231-249.
http://journals.sagepub.com/doi/abs/10.2466/21.07.PR0.114k11w6

Ross, R.K., Bernstein, L., Lobo, R.A., Shimizu, H., Stanczyk, F.Z., Pike, M.C., and Henderson, B.E. (1992). 5-apha-reductase activity and risk of prostate cancer among Japanese and US white and black males. Lancet, 339, 887-889.

http://www.sciencedirect.com/science/article/pii/014067369290927U

Shur, M.D., Palombit, R.A., and Whitten, P.L. (2008). Association between male testosterone and friendship formation with lactating females in wild olive baboons (Papio hamadryas anubis). Program of the 77th Annual Meeting of the American Association of Physical Anthropologists, p. 193.

http://onlinelibrary.wiley.com/doi/10.1002/ajpa.20806/epdf

The African outlier

While birth rates fall everywhere else, sub-Saharan Africa remains an outlier of high fertility (2009).

Throughout most of the world, the demographic transition has played out as predicted. Fertility rates have fallen to replacement level and even lower, first in Europe and North America and more recently in East Asia, Southeast Asia, the Middle East and North Africa. The exceptions are societies where religious fundamentalists exert a strong influence on childbearing: Mormons and Amish in the United States, and Islamists in Saudi Arabia, Afghanistan, and Pakistan.

There is, however, an area where the demographic transition seems permanently stalled for reasons unrelated to religion. That area is sub-Saharan Africa. How come?

This puzzle caught the attention of anthropologist Patricia Draper back in the late 1980s. Sub-Saharan Africa had become an outlier of high fertility, even after adjustment for those factors that were lowering birth rates elsewhere. This excess fertility seemed to be due to a different social environment for mating and reproduction:

[…] in much of Africa, not only among country people but among urban populations as well, there persists high fertility and a pattern of parental investment in which both mothers and fathers invest, by Western standards, relatively little in each offspring and pursue a pattern of delegated parental responsibility (Draper and Harpending 1988). Coupled with low investment parenting is a mating pattern that permits early sexual activity, loose economic and emotional ties between spouses (Potash 1978), and in many cases the expectation on the part of both spouses that the marriage will end in divorce or separation, followed by the formation of another union (Aldous 1962; Lowy 1977; Oppong 1974; Mair 1953; Gibson 1958; Hunter 1961; Tuupainen 1970). Polygyny, still widespread in Africa, inhibits high male parental investment in children […] (Draper, 1989, p. 145-146)

In sub-Saharan Africa, parenting is assumed primarily by the mother and her kin. The parents, especially the father, are thus under much less pressure to limit family size. As Draper notes :

[…] people do not scale down expectations for large numbers of children precisely because their understandings about available resources take into account reservoirs of surrogate care among their kin. […] African men may see no urgency in reducing the numbers of their progeny precisely because a characteristically African set of socioecological circumstances permit many children to survive despite low father contribution to child support. (Draper, 1989, p. 147)

This is in contrast to the situation of parents elsewhere, particularly in modern urban settings, where a larger family perceptibly reduces the resources left over for the parents.

Will things change in the near future? Much depends on whether African families adopt the Eurasian marriage system, i.e., monogamy, long-lasting marital bonds, and high parental investment in children (including high paternal investment). To date, despite the efforts of missionaries and government authorities, there has been little change in this direction.

African men, in particular, are reluctant to assume a more active parental role:

Much of rural African subsistence is based on the work of women in their gardens; men make only modest contributions. Typically, rights in land are held by men by virtue of their membership in kinship or village units. A man who wishes to add another wife is under few constraints (provided his kinship group has the land and bridewealth), since women, in effect, pay their own way. They produce food, and they rear children. In rural areas, when a man marries an additional wife, he is awarded additional fields for this woman and her children (Bryson 1981). The importance of male labor to support such households is reduced. In former times, before colonially imposed peace, the male role in defense was important. But since central governments have been present, men who remain in rural villages spend their time in leisure, in management of household labor, or in local political affairs (Potash 1978). More recently, men absent themselves for long periods in migratory labor. They send remittances home that help to pay school and medical fees and to buy clothing. Nevertheless, the work of feeding people remains with women (Hafkin and Bay 1976; Vaughan 1983).

[…] Many efforts have been made to induce African men to increase their agricultural labor. The more successful of such ventures have followed the introduction of cash crops and the development of markets. Men are more willing to work at raising cash rather than traditional subsistence crops. However, since most cash crops are not food crops, women continue to do the subsistence farming, for which cash conversion is less possible, and they work even harder, since the men are busy with cash crops and have even less time for periodic help in the family gardens at clearing and harvest time (Obbo 1980; Whiting 1977; Kelley 1981). Characteristically, men do not return their earnings from cash crops to the household economy. This money is held separately and spent by men on their own projects (Vellenga 1983; Abu 1983; Bryson 1981). (Draper, 1989, p. 152)

As Africans migrate to other parts of the world, they tend to recreate the African marriage system in their host countries by using local people and institutions as “surrogate kin” Draper describes the situation in England, where young African couples often place their children in foster homes:

As might be expected, the outcome for all concerned does not work in the way it is expected to in West Africa. The foster parents interpret the infrequent visiting of their wards’ “real” parents as signs of parental neglect and become strongly attached to the foster children. This sometimes results in legal suits for transfer of custody to the foster parents (Ellis 1977). Meanwhile, the African parents make no comparable assumption that the delegation of care means they have surrendered formal rights in children. They consider that by having made safe and reliable arrangements for the care of children and by regular payment of fees, they are dispatching their immediate responsibility. (Draper, 1989, p. 164)

Ironically, when infertile Western couples go to Africa to adopt, as is increasingly the case, the adopted child evokes a degree of parental attachment that it would not normally evoke from its natural parents—even in the best of circumstances.

Reference

Draper, P. (1989). African marriage systems: Perspectives from evolutionary ecology, Ethology and Sociobiology, 10, 145–169.

http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1007&context=anthropologyfacpub

More on paternal investment and agriculture

Many anthropologists have noted a correlation between the incidence of polygyny and the predominance of women in agriculture. The more women are responsible for producing food, the likelier men will have second or third wives. This correlation is especially evident in sub-Saharan Africa, where food is produced mostly by mothers hoeing garden plots and where fathers are highly polygynous (see Goody 1973 for a review of the literature).

This correlation has exceptions, even in sub-Saharan Africa. Goody (1973) points to the West African savannah where humans have adapted to this semi-arid zone by developing a very different system of food production. Here, women plant grain and help with the harvest but men do the rest of the farm work. Nonetheless, polygyny rates are as high as in other regions where women produce most of the food.

How do these men manage to feed all of their wives and children? Well, they don’t, at least not entirely. In this region, as in West Africa in general, women obtain food for themselves and their families through trade, i.e., by tending stalls in village markets and by gathering wood for sale. There is also food provisioning from unmarried sons. Since young men have to wait some fifteen years to get married (because so many women are taken by older polygynous males), the unmarried sons in a family are called upon to help their father provide for his wives and offspring.

This system is not without disadvantages. Ideally, a woman should specialize in activities that are compatible with infant care and transport, i.e., that can be done within a relatively small land area. This is why women tend to specialize in food gathering and hoe gardening. Collecting and selling wood requires much longer walking distances. The risks are higher not only for any infants being carried but also for the mother.

Nor does this system work very well for young men. Some of them die during the fifteen or so years they spend waiting for a bride. Their genetic contribution to the next generation is limited to kin selection (by helping out their polygynous fathers), illicit sex, and abduction of women during warfare.

If humans could design their societies, things might be done differently. The polygyny rate could be reduced to give all men early access to marriage and to equalize the burden of parental investment for men and women. This would make everything a lot fairer

Of course, societies are not designed. They come about ad hoc. And fairness has nothing to do with it either. When humans stumble into a new environment, they try to adapt while also trying to satisfy their existing inclinations and predispositions, these being psychological adaptations to the previous environment. In time, new adaptations will arise through natural selection, but again this takes time—all the more so if a way is found to sustain the existing ones.

References

Goody, J. (1973). “Polygyny, economy and the role of women,” in J. Goody (ed.). The Character of Kinship, Cambridge: Cambridge University Press, pp. 175-190.

Paternal investment and agriculture

In sub-Saharan societies, female-dominated agriculture is associated with low paternal investment and high polygyny rates. Why? The short answer is that year-round tropical agriculture enables women to meet their food needs and those of their children without a male provider. Paternal investment thus tends to fall to zero and men are free to maximize their reproductive fitness by mating with as many women as possible.

Long answer: this difference between tropical and non-tropical humans was already present before agriculture. Even during the hunter-gatherer stage, men provided more food for their mates and offspring with increasing distance from the equator, apparently because the longer winters made food gathering impossible for women during much of the year. Thus, when agriculture became the new mode of food production, men were much more predisposed to exploit its possibilities outside the tropics.

For instance, most livestock were domesticated in Europe and Asia, the guinea fowl being the only food-producing animal to have been domesticated in sub-Saharan Africa. Livestock domestication thus seems to have been limited not only by technical constraints (availability of wild animals with the right characteristics) but also by psychological constraints (relative predispositions of men and women to take part in food production).

Wherever men had previously provisioned their families with food from hunting, they were more inclined to do the same by domesticating game animals—often the same ones they used to hunt.

I discuss some of these points in my latest article: "Sexual Selection and Human Geographic Variation."

Reference

Frost, P. (2008). Sexual selection and human geographic variation, Special Issue: Proceedings of the 2nd Annual Meeting of the NorthEastern Evolutionary Psychology Society. Journal of Social, Evolutionary, and Cultural Psychology, 2(4), pp. 169-191.
http://www.jsecjournal.com/articles/volume2/issue4/NEEPSfrost.pdf

Does paternal investment increase child IQ?

The latest issue of Evolution and Human Behavior has an article on paternal investment and IQ. Using a longitudinal dataset of children born in Britain in 1958, Nettle (2008) found a significant positive correlation between a child’s IQ at age 11 and the father’s degree of family involvement. The less a father cared for his offspring, the less intelligent they were. Nettle concluded that paternal investment affects childhood IQ.

Now, correlation is not causation. It can be shown, for instance, that Presbyterian ministers in Boston have earnings that significantly correlate over time with the price of rum in Havana. But that doesn’t mean they’ve been dabbling in the rum trade. It simply means there’s a common causal factor, in this case the North American business cycle.

Similarly, a common cause may explain the correlation between low investment by fathers and low intelligence in their children. Deadbeat dads tend to be more present-oriented and probably less intelligent. Since intelligence has a large heritable component, their children would be less intelligent on average.

In all fairness, the Nettle study did control for social class, which in turn partially controls for time preference (i.e., whether the fathers were present-oriented or future-oriented). Specifically, the fathers were coded in terms of five occupational categories: professional, managerial and technical, skilled, partly skilled, and unskilled. I doubt, though, that this factor would have accounted for most variability in time preference. Even within the British working class, there is considerable variation, notably by religion and ethnicity, in the respective weighting that people give to present impulses versus future obligations.

Reference

Nettle, D. (2008). Why do some dads get more involved than others? Evidence from a large British cohort. Evolution and Human Behavior, 29, 416-423.