Sex Differences in Intelligence

There have been well known claims about sex differences in intelligences: men have IQs higher by several points in adulthood, that men have greater variance in IQ (more geniuses, but also more stupid men), better visuo-spatial skills, etc.

More recent studies have shown that there is no difference in general cognitive ability (g) between men women, and the apparent emergence of a gap during the ¬†teenage years in some studies was a result of study designs and samples, not real population differences (see Deary’s 2012 ‘Intelligence’ review).

The question of greater male variance in IQ is interesting, because, within populations that variance has been quite consistent. From a 2012 global study on math achievement:

The VR [variance ratio] measured for any given nation was quite reproducible, that is, it rarely differed by more than 20 percent from one test administration year to the next, among students in different grades, or between the PISA and TIMSS; typically, it differed by at most 10 percent…

However, while it is consistent within nations, it is very different across nations:

White bars = Muslim countries; Grey bars = non-Muslim countries

Here’s a list of countries and their variance ratios (boy’s variance / girl’s variance):

From this they conclude:

… that both variance and VR in mathematics performance vary greatly among countries. Confirming our earlier finding ([21]), we also conclude that VR is reproducibly essentially unity for some countries. These findings are inconsistent with the greater male variability hypothesis

They also point out the issue of the influence of sampling in causing differences in variance, similarly to how sampling issues seems to have been the cause of the erroneous findings of men having higher IQs – at least in explaining certain countries, such as these:


On another note, in Iran apparently 70% of science and engineering students are women (source)

Monogamy and Western Civilization

There was a case recently, in British Columbia, which ended in retaining the illegality of polygamous marriage. It revolved around a breakaway Mormon cult in Bountiful, B.C. As part of the proceedings, three academics provided briefs, which are both very interesting. Walter Scheidel (pdf) of Stanford, and Joseph Henrich (pdf), of UBC. Henrich has just published a paper on the same subject. Another paper by Scheidel on the origins of western monogamy is here. See also the affidavit by John Witte Jr. on the history of western ethical and legal outlooks toward polygamy (pdf).

What I’m interested in is the connection between monogamy in western civilization and the evolution of perceptions towards marriage and women.

Ancient Greece and Rome both had, as Scheidel describes it, ‘socially imposed universal monogamy’, and likewise Christianity (unlike Judaism), seems to have implicitly rejected polygamy from the beginning, and explicitly within a short amount of time.

So the earliest form of socially imposed universal monogamy dates to the ancient Greeks. And most interestingly, it seems to be connected to the democratizing and egalitarian ethos of the period – (see the paper “Solon and the Institution of the ‘Democratic’ Family Form”; as well see Scheidel’s papers). The Greeks themselves considered this to distinguish them from the barbarians. The exact roots of socially imposed universal monogamy are unfortunately unclear, so it is hard to be certain about the social forces driving it in ancient Greece. But the cultural memory of polygamous marriages was still present, and represented in epics like the Iliad. So it came after that, presumably. We find in the laws of Solon an apparent intention to re-organize family law in order to equalize Athenian male citizens, suggesting the socially imposed aspect of it came into play in connection with egalitarian (among men) ideals.

Rome, too, had universal monogamy for as long as we know. What caused this? It’s even harder to say, but after all Rome was a republic, had heavy influence from Greek society, etc. – but, as Scheidel points out, in the end, we basically just know that Greece and Rome were monogamous. No compelling explanation for why both of them specifically has yet been forthcoming.

I should note that at this point that Laura Fortunato argues that monogamous marriage systems date back much further among Indo-Europeans. However, given the evidence of polygamy from numerous ancient sources both in their own prehistory, in their discussions of neighbouring Indo-Europeans, etc., it is clear it could not have been a universal monogamy, even if it was overwhelmingly prevalent, and perhaps served as a precursor to the Greco-Roman variety.

But what interests me is the connection between monogamy and egalitarianism. In the same way that democratic ideals eventually expanded beyond the realm of male citizens, to women and slaves, I wonder if the egalitarianism inherent in monogamy eventually had an impact on the view of women in western civilization. Even from the time of Socrates and Plato, to the period, of say, 1st century imperial Rome and Greece, there seems to me to have been a shift in attitudes towards women. Compare for example Socrates attitude towards his wife at his death, compared to that of Seneca towards his wife – despite the death scene of Seneca being modeled on that of Socrates.

Or, as an example of how these things change meaning over time – consider Plutarch’s interpretation of Solon’s marriage laws – ie. he throws in ‘pure love’ as a motivation, which may be a reflection on the recursive nature of the institution of monogamy, because Solon certainly never emphasized that, and neither would his contemporaries:

In all other marriages he forbade dowries to be given; the wife was to have three suits of clothes, a little inconsiderable household stuff, and that was all; for he would not have marriages contracted for gain or an estate, but for pure love, kind affection, and birth of children. When the mother of Dionysius desired him to marry her to one of his citizens, “Indeed,” said he, “by my tyranny I have broken my country’s laws, but cannot put a violence upon those of nature by an unseasonable marriage.” Such disorder is never to be suffered in a commonwealth, nor such unseasonable and unloving and unperforming marriages, which attain no due end or fruit; any provident governor or lawgiver might say to an old man that takes a young wife what is said to Philoctetes in the tragedy-

“Truly, in a fit state thou to marry!”

and if he find a young man, with a rich and elderly wife, growing fat in his place, like the partridges, remove him to a young woman of proper age. And of this enough.

Musonius Rufus, the ‘Roman Socrates’ and one of the most prominent of Roman philosophers, taught:

The husband and wife, he [Musonius] used to say, should come together for the purpose of making a life in common and of procreating children, and furthermore of regarding all things in common between them, and nothing peculiar or private to one or the other, not even their own bodies. The birth of a human being which results from such a union is to be sure something marvelous, but it is not yet enough for the relation of husband and wife, inasmuch as quite apart from marriage it could result from any other sexual union, just as in the case of animals. But in marriage there must be above all perfect companionship and mutual love of husband and wife, both in health and in sickness and under all conditions, since it was with desire for this as well as for having children that both entered upon marriage. Where, then, this love for each other is perfect and the two share it completely, each striving to outdo the other in devotion, the marriage is ideal and worthy of envy, for such a union is beautiful. But where each looks only to his own interests and neglects the other, or, what is worse, when one is so minded and lives in the same house but fixes his attention elsewhere and is not willing to pull together with his yoke-mate nor to agree, then the union is doomed to disaster and though they live together, yet their common interests fare badly; eventually they separate entirely or they remain together and suffer what is worse than loneliness.

And here is Hierocles (early 2nd century):

[T]he beauty of a household consists in the yoking together of a husband and wife who are united to each other by fate, are consecrated to the gods who preside over weddings, births, and houses, agree with each other and have all things in common, including their bodies, or rather their souls, and who exercise appropriate rule over their household and servants, take care in rearing their children, and pay an attention to the necessities of life which is neither intense nor slack, but moderate and fitting.

My general point here is that classical attitudes did change over time, and it is possible socially imposed universal monogamy may have had the effect of promoting the idea of marriage as a partnership in which love was important. Not just in the ancient world, but perhaps served to encourage that line of thinking throughout until now.

I won’t bother going much into Christianity and all the intermediate history, but we know that Christianity strongly adopted and enforced Greco-Roman monogamy, and spread it throughout Europe, with an even more strict sexual morality. In fact the motivations of the Catholic church have been argued to be very similar to the Greeks: by insisting on monogamy and making all children born from other women bastards without rights, one means of accruing power was removed (and in the case of no legitimate heirs, property went to the church). Attitudes towards women were also, of course, influenced by Christian teachings, and also the attitudes of Germanic and Celtic societes. But I will skip all that, and will quote from one of the earliest Japanese visitors to Europe in the mid-19th century (from “The Japanese Discovery of Victorian Britain: Early Travel Encounters in the Far West”):

“Kawaji … had ample opportunity to observe the European tradition of chivalry in practice. It seemed to him that ‘the ladies on this ship possess great authority and assume an air of importance equivalent to that of an imperial princess in our land’. He was curious to discover ‘the British custom of paying inordinate respect to ladies; they take their seats before their husbands and sit in the best places at mealtimes as well’. Later in the voyage he concluded that, ‘of all the countries in the West, Britain has the most pronounced custom of paying respect to ladies. From what I have seen on this ship, it seems that, when talking to a lady, you take off your hat and treat her most politely. This is the reverse of the ranking in our country, and I find it most astonishing’.

“Kawaji felt moved to ask for some clarification on the subject of chivalry, but was disappointed to learn that ‘this is an old custom, and there is no particular explanation for it’. He was, nevertheless, impressed by the fact that ‘the custom of holding ladies in such respect enables them to travel thousands of miles overseas on their own without coming to any harm’.

I also remember reading a similar quote by an Ottoman official visiting a western European in the 19th century in one of Bernard Lewis’ books; Lewis took the view that the strict enforcement of monogamy was one of the reasons women in western Europe were better off than women elsewhere.

Of course in many places monogamy was overwhelmingly common, even though polygamy was accepted. This distinction could nevertheless leave room for quite a bit of difference in perception, even if the numbers of people actually in a polygamous marriage are not large.

One problem with my general interpretation is that, like a lot of other developments generally attributed to Western Civilization, or Christianity, it in reality seems to be more of a (north-)western European thing. Many other factors could have played into it as well (‘it’ being women’s rights) – the Western European Marriage system, for one.

Still, monogamy seems to have a connection to various forms of egalitarianism, whether between men, or between men and women. It could be a coincidence of course, but then it was born in the move towards Greek democracy, and Roman Republicanism. Perhaps rather than being a direct cause, it is part of a western package of beliefs that mutually reinforce each other. If that is the case, the dangers in isolating one aspect, like socially imposed universal monogamy, and asking whether it specifically can be relinquished, is risking a lot for no apparent benefit. But given the recent enthusiasm for abolishing western civilization, I guess it’s unlikely to be maintained for long.