Prior post: Rise and fall of empires: genetic version? (2017)

I found this stuff a while ago, and tweeted it, but I wanted to save it properly so it doesn’t get forgotten again. Blogging is extended memory. I reckon my mortality risk at Twitter is about 30% each year. Accounts have been banned for less. With that gone, I lose ability to search my own past thoughts so easily!

In prior times, cyclical theories of history were quite popular. Raymond Cattell for instance talks as if everybody agrees with these:

In the path of progress of England and most civilised nations stands a threat, challenging all who have the intelligence to perceive it.

For it is not a menace apparent to all eyes, as are the perils of economic collapse, or cultural and religious confusion, nor is it so easily dramatised as political reaction or war. Yet it strikes insidiously at the very roots of national life and brings all these evils and many more besides in its train. I refer to the approach, foreseen by scientists a generation ago, of a grave decline in the level of national intelligence. To meet and over-come this enemy is the special task of the twentieth century, and if the victory is gained there is little doubt that history will rank it as the most important achievement of Western culture, for no civilisation has achieved it before.

Let us scrutinise the threat more closely and glance at the effects likely to occur if the danger materialises. Certain historians who have recently made their subject a scientific study, an affair of measuring and calculation, tell us that the decline of the early Eastern civilisations, of Greece and of Rome, was primarily due to a biological withering of those strains of the population bearing high mental capacity.1 To create a civilisation, to let it burst forth in flower from a previous state of barbarism, the race concerned must first accumulate a rich of crop men—or rather of family strains—possessed of great natural mental capacity. To maintain a civilisation in good working order it must retain an adequate proportion of these relatively gifted strains.

Under every system of civilisation yet known there has been an ineradicable tendency for the population to be recruited increasingly from the sub—men. If generation after generation they have a birth rate above those of good average intelligence, and if the strains of high intelligence limit their breeding practically to the point of dying out, it does not require long, in historical time, for the quality of the breed to become entirely different. The unhappy country “grows thin on top,”loses first the fine lustre of its genius, then its moral culture and political stability and finally its arts, its material standards of living and “civilisation” itself.

Not one civilisation has yet escaped this sequence and mystics such as Spengler have enshrined the occurrence in the dignity of an inexorable natural (or supernatural)law, pointing with blood—curdling cries of doom to the omens in our own midst which foreshadow the “Decline of the West” decreed by destiny. But the temper of the scientist—-—of the psychologist and biologist looking at social problems—inclines him to regard it as a natural disease which, if the scientist is given a chance, may yet be understood and mastered.

Nor did human progress suffer permanent defeat as a result of these shipwrecks in eras when civilisations were small centres of light in a sea of barbarism, though doubtless the situation was desperate and forlorn enough to those who saw all that they valued sinking into night. In the surrounding masses of barbarians, the ancient law of the survival of the fittest constantly accumulated, through blood and agony, a preponderance of survivors having quick intelligence and determined foresight. These broke in upon the decrepit civilisation and, if they were minded to pick up the social heritage at the point where it had dropped from the nerveless fingers of its former keepers, generally cultivated it into blossoming with fresh vigour.1

But when the lingering death of civilisation is likely to stretch across the whole world and no gifted outsiders are left anywhere to put it out of 1ts misery, the menace of decline assumes a more forbidding aspect. It 15 a case of internal cure or nothing. Consequently, to men of ideals and determination—indeed, to all who value the slow-built heritage of civilisation—no social, political or religious problem calls so urgently for attention as this one. It requires action and thought on unprecedented lines,directed to discovering and righting that hitherto-ignored error in the construction of civilisation which condemns it to a perpetual and futile cycle of breakdowns and frustrations.

Western civilisation, it is true, has had an unbroken run of some six hundred years of reasonably active intellectual and social life. It wears still, save for a few disconcerting symptoms, an air of serene or optimistic progressiveness, in this respect achieving something of a record. 2 A careful sociological analysis would prob—ably shew3 that owing to a fortunate coincidence of property customs, migration, the incidence of disease and recruiting for war, blind spots in Christian practice,etc., the survival rate of the more able has been about the same as that of the less gifted over most of this period. Even two generations ago when Francis Galton first drew attention to the extent of inheritance of mentaland physical traits and began to examine birth rates——thereby founding the science of eugenics—there was no convincmg evidence of anything but a happy state of affairs in the nation’s breeding of intelligence.

It is only in the last thirty years that a number of signs discernible to the sociologist have pointed to the grim conclusion that we have entered on a phase in which low—grade mentality is reproducing itself with unhindered prolificness, whilst families of more than average intelligence are failing even to maintain their numbers. Unfortunately this evidence, which I have discussed in connection with other problems of social psychology elsewhere,5 is of too oblique and inferential’ a nature for its convincingness to be grasped by those not at home in the statistical analysis of social problems.Rhetoricians can blur its outlines with a word and anyone with strong political prejudices can ride rough—shod over its delicate mosaic of reasoning. If right-thinking men and women are to be united in a course of action, therefore, it is urgently necessary to uncover direct evidence, proving up to the hilt and beyond emotional disputation the state of affairs that actually exists.

He gives these references:

See Seeck, Geschichte des Untergang: der Antiken Welt, Vol. II ; Nilsson, Imperial Rome; Tarn, Hellenistic Civilisation, 1930, p. 91; Fisher, R. A., “The Problem of the Decay of Civilisation,” Eugenics Review, 1926; Rostovtzeff, ‘ Social and Economic History of the Roman Empire; Gunther, The Racial Element: of European History; Dill, Roman Society; and McDougall, National Welfare and National Decay.

It is not asserted that the disappearance of ability was the only cause of collapse. There were obvious economic and military causes. But I think the social psychologist to-day would consider many of these other factors as derived from alterations in the distribution of mental capacity, just as he would consider the latter to arise from social customs and ideals. Nor does one suppose that history exactly repeated itself in each decline. To-day, for example, the decline of mental capacity would have far more devastating results than in previous civilisations.

A particularly nice later reference is The Fate of Empires and Search for Survival (1946) by John Glubb, a British army officer. He basically claims that civilizations tend to last a specific length, apparently the amount of time the cycle takes on average:

This is not quite right, but I guess integrating this kind of thing is a job for the cliodynamics people (Turchin, you reading this?).

In modern times, German historian Volkmar Weiss has also discussed them at length in his under-read Mankind Quarterly (2007) paper The Population Cycle Drives Human History -from a Eugenic Phase into a Dysgenic Phase and Eventual Collapse.

There is just that one problem, which is that no one seems to have any actual fertility rate data for the Roman empire. There’s a lot of claims that their fertility started dropping, and even had internal dysgenics (in the sense of Nyborg 2012), like we saw in the 1960s. Here’s Frank Salter (On Genetic Interests, 2003) quoting a Roman of some repute:

Actual behaviour regarding group size. There is not a strong research litera­ture on investment in ethnic, as distinct from personal, reproduction. Competitive breeding has occurred in historical times, 59 though whether it has been an im­portant factor in human evolution is the subject o f the debate over genetic group selection. This has occurred at least since Roman times, when the Emperor Augustus approved legislation in 18 BC that promoted larger families among his own patrician class. Augustus offered honour and prizes to fathers, but to bachelors he was stem, delivering his rebuke with the gravity appropriate for matters of ethnic survival:

. . . mine has been an astonishing experience: for though 1 am always doing every­ thing to promote an increase of population among you and am now about to rebuke you, I grieve that there are a great many of you. . . . We do not spare murderers, you know. . . . Yet, if one were to name over all the worst crimes, the others are as naught in comparison with this one you are now committing . . . for you are committing murder in not begetting in the first place those who ought to be your descendants; you are committing sacrilege in putting an end to the names and honours of your ancestors; and you are guilty of impiety in that you are abolishing your families, . . . overthrowing their rites and their temples. Moreover, you are destroying the State by disobeying its laws, and you are betraying your country by rendering her barren and childless; nay more, you are laying her even with the dust by making her destitute of future inhabitants.60

One can find people who think this is related to loosening of sexual morals. The impressive part about this theory is that it dates back to 1930, that is, before the sexual revolution (or decay) of the late 1960s in our own civilization! Sex and culture is the name of the book by J. D. Unwin from 1934. There’s a good summary here:

A few days ago I finished studying Sex and Culture for the second time. It is a remarkable book summarizing a lifetime of research by Oxford social anthropologist J.D. Unwin.[1] The 600+ page book is, in Unwin’s words, only a “summary” of his research—seven volumes would be required to lay it all out.[2] His writings suggest he was a rationalist, believing that science is our ultimate tool of inquiry (it appears he was not a religious man). As I went through what he found, I was repeatedly reminded of the thought I had as a philosophy student: some moral laws may be designed to minimize human suffering and maximize human flourishing long term.

Unwin examines the data from 86 societies and civilizations to see if there is a relationship between sexual freedom and the flourishing of cultures. What makes the book especially interesting is that we in the West underwent a sexual revolution in the late 1960’s, 70’s, and 80’s and are now in a position to test the conclusions he arrived at more than 40 years earlier.

Here are a few of his most significant findings:

  1. Effect of sexual constraints: Increased sexual constraints, either pre or post-nuptial, always led to increased flourishing of a culture. Conversely, increased sexual freedom always led to the collapse of a culture three generations later.

  2. Single most influential factor: Surprisingly, the data revealed that the single most important correlation with the flourishing of a culture was whether pre-nuptial chastity was required or not. It had a very significant effect either way.

  3. Highest flourishing of culture: The most powerful combination was pre-nuptial chastity coupled with “absolute monogamy”. Rationalist cultures that retained this combination for at least three generations exceeded all other cultures in every area, including literature, art, science, furniture, architecture, engineering, and agriculture. Only three out of the eighty-six cultures studied ever attained this level.

  4. Effect of abandoning prenuptial chastity: When strict prenuptial chastity was no longer the norm, absolute monogamy, deism, and rational thinking also disappeared within three generations.

  5. Total sexual freedom: If total sexual freedom was embraced by a culture, that culture collapsed within three generations to the lowest state of flourishing — which Unwin describes as “inert” and at a “dead level of conception” and is characterized by people who have little interest in much else other than their own wants and needs. At this level, the culture is usually conquered or taken over by another culture with greater social energy.

  6. Time lag: If there is a change in sexual constraints, either increased or decreased restraints, the full effect of that change is not realized until the third generation.(Note: I’ve added a clarifying footnote at the end of this article. See footnote #13)

As you can imagine, a book written by a social anthropologist in 1934 is not the most scientific in the sense of quantitative rigor one can hope to find. Nevertheless, the idea is intriguing considering the strongest decay of western civilization seems to be after the 1960s phase.

A particularly interesting theory of ancient Roman fertility decline is that… they took too many hot baths! A. M. Devine writes in The low birth-rate in Ancient Rome: A possible contributing factor (1985):

There is considerable evidence to show that Roman society in the late Republic and early Empire was afflicted by a low birth- rate. Augustus in 18 B.C. found it necessary to pass the lex Iulia de maritandis ordinibus in the hope of raising the birth-rate by penalizing the unmarried and the childless. In 9 A.D. he attempted to supplement this law with the lex Papia Poppaea. The very existence of this legislation indicates that the problem of childlessness was widespread and long-lasting, a view which is further to this subject in Latin literature1). supported by references A number of theories have been put forward by scholars to explain this fact. Among these are the notion that Romans practised contraception and abortion to avoid the birth of unwanted from a form that members of the upper classes suffered children2), of dysgenic lead poisoning caused mainly by the use of lead cooking vessels, which rendered many of them sterile3), and that a form of natural selection in favour of infertility took place, due to the common practice among noble males of trying to marry heiresses who were the sole children of their families and therefore in their turn4). Any or all of likely to demonstrate low fertility these practices may have been genuine contributing factors to the low birth-rate in Rome. However it is the contention of this paper that a far more significant factor to the low birth-rate contributing was the Roman practice of taking very hot daily baths.

There can be little doubt that the baths enjoyed by the Romans were very hot and very frequent. According to Pliny the Elder (PL N.H. 36.121) the census of baths taken by Aerippa in 33 B.C. snowed that there were 170 baths in Rome and this number undoubtedly increased with time. It is common knowledge that Romans, even of the lower social classes, were in the habit of taking daily baths and some seem to have bathed even more frequently (Petronius, Satyricon 72). The usual routine11) to warm up er was to play a game of ball in the sphaeristerium before entering the tepidarium where he would sweat for a while with his clothes on. He would then undress in the apodyterium and be anointed with oil. After this he would sweat profusely in the caldarium and even more profusely in the laconicum, which was directly over the hypocaust. The next step would be to have warm, tepid and finally cold water poured over him, after which he would be scraped with a strigil and sponge

I wonder if we could reconstruct fertility rates in ancient Rome by looking at genealogies and sequencing large graveyards? People are buried next to relatives with some frequency which is affected by the number of relatives, hence the fertility rate. Anyway, the theory here is both one of dysgenics in that the more elite Romans could better afford taking a lot of baths, but also general decline in fertility, as even commoners were taking quite a few of them. Does the supposed causal claim even hold up? Well, I was able to find one tiny (n = 10 Finns) longitudinal study of saunas and semen quality, and, even with this sample size one can find p < .01 longer term (3 months) effects. Difficult to believe? Maybe! Needs a replication.

The more conventional but still fun theory is that the Romans were a bit overeager with their use of lead. Now, the modern reader is wondering: why use lead for stuff? Well, lead is soft and melts easily, so it is really quite easy to work with. It is unfortunately heavy, but one can deal with that. Of course, the ancient Romans did not know about heavy metal poisoning, so their use of this metal in cooking and drinking storing equipment was unfortunate to say the least. If wealthier and smarter people somehow got more lead exposure, this could induce dysgenics as well. Some works on this topic include: Lead and lead poisoning in antiquity (1983) by Jerome O Nriagu, though reviewers were not too happy. A cooler paper is Roman Culture and Dysgenic Lead Poisoning (1965) by a Seabury Colum Gilfillan, There is a book from 1990 too (Rome’s Ruin by Lead Poison). again in Mankind Quarterly! Gilfillan was an interesting enough guy that historians write biographies of him still.


Looking ahead, it is clear what we need to do to clarify these things:

  • Scale up our ancient genomics by digging up more graveyards and releasing the data to the public for maximum research efficiency. MORE BONES! Zooming out, it will be interesting to see if e.g. the various Persian empires involves a local maxima in polygenic scores for civilization-promoting traits, not least intelligence but also others.
  • Reexamine the hypotheses mentioned above with modern datasets: lead poisoning theory, hot bath semen quality theory, sexual mores theory.