Of mouse utopias and men
DR EDWARD DUTTON asks whether a new interpretaion of a classic experiment warns of the death of humanity...
Mice, like all animals in the wild, battle the savagery of selection. They are subject to predators, cold, starvation and disease. Male mice must fight it out to control the largest harem of females; mothers will reject runts among their offspring. This means that only the mice that are physically and mentally best adapted to their environment pass on their genes. In every generation, mice that have mutant genes – causing poor immune systems, physical weakness or stupidity – are coldly cleansed from the population. Red in tail and squeak, this is natural selection – and until the Industrial Revolution we humans were subject to it as well.
Until about 1800, 40 per cent of us would die before reaching adulthood. And this wasn’t a random 40 per cent: in a society with no proper medicine, it was anybody who didn’t have a superb immune system. Competing for survival in this unforgiving world, intelligence (which is about 80 per cent genetic) gave people a huge advantage, because it allowed them to become wealthy and better able to protect themselves from disease with healthier food and living conditions. So, according to cutting-edge psychologists, intelligence was selected for too, and there is clear evidence that those who lacked it had fewer surviving children. 1 In 16th and 17th century Essex and Suffolk, the richer 50 per cent of testators had 40 per cent more surviving children than the poorer 50 per cent, something that held roughly true throughout Europe. 2
What all this meant was that the population numbers remained at the level the agrarian ecology could support. This, in England, was less than six million. The Industrial Revolution changed all this, because it pretty much put an end to natural selection, meaning that economic and scientific growth outpaced population growth. With inoculations, rapidly expanding medical technology and skyrocketing living standards, child mortality fell from 40 per cent to less than two per cent: now, all the people with poor immune systems and genetic health problems – all the people (about 90 per cent of us!) with ‘high mutational load’ – were able to pass on their genes, as were their children, grandchildren and great-grandchildren, leading to an ever-growing build-up of mutation.
This is a unique situation in human history. Previous civilisations – Greece, Rome, China – always collapsed just at the beginning of an Industrial Revolution. But for reasons that are unclear the Christian West didn’t. It continued selecting for intelligence for longer – long enough for intelligence to get high enough for the major breakthroughs to occur. So, what happens to a species when you completely remove natural selection? Well, we know what happens to mice: it’s frightening, all the more so because it seems to be happening to us today.
In 1968, at the University of Maryland, eccentric Tennesseeborn ethologist John Calhoun (1917-1995) began a groundbreaking experiment: he created a ‘Mouse Utopia’. This was a veritable heaven for mice in which there would be: (1) No emigration by lower status mice to suboptimal habitats, as there would be abundant replica habitats and the utopia would be impossible to escape from. (2) No resource shortage or inclement weather. (3) No epidemics. (4) No predators. 3
In July 1968, four pairs of house mice were introduced into the 16 cell ‘mouse universe’. After 104 days (Phase A), the first litter was born, resulting in social turmoil as the mice learned to live together. Thereafter, the population rose exponentially, doubling around every 55 days until it reached 620. This is, of course, exactly what happened after the Industrial Revolution: enormous population expansion.
This marked the start of Phase B. At this point, population growth slowed until doubling occurred only every 145 days, just as we have seen in the Western population, where there is ‘below-replacement fertility’. Periodically, in Phase B, young born at this point would have their own young, contributing to the growth of population in which mice, unlike in the wild, were able to become elderly in significant numbers, just like in the West.
By the end of Phase B, all the most desirable space was filled with polygynous social groups controlled by dominant males. The more dominant the male, the larger and more fertile his social group tended to be. There were 14 social groups composed of 150 adults. Each group was made-up of about 10 adults, including a dominant male, associated males and females, and their offspring. There were 470 such offspring and they had all received good maternal care and early socialisation. So, there were three times as many younger than older animals, a far greater ratio than would exist in the wild.
At day 315, Phase C began and population growth slowed markedly. Normally, more mice survive to maturity than can find social niches and so these lower status mice will tend to emigrate in search of such a niche. As this was prevented, a large number of males – unable to successfully compete for a social niche – simply withdrew physically and psychologically from territorial males and ganged up together. They would occasionally fight each other over trivial issues but they would do little else. Low status females would withdraw to (less desirable) high nesting boxes but were not aggressive towards each other. However, territorial males were constantly confronted with subordinate males trying to take over their
Normally, more mice survive than can find social niches
territory and, as there were so many of them, the ability of territorial males to control their territory declined.
This left nursing females exposed to nest invasion. The females would then take on the role of the absent male, becoming extremely aggressive and even generalising this aggression to their own young: babies would be ejected from the nest too young and abandoned by their mothers during transit to new nest sites. Conception declined, while reabsorption of foetuses increased. This behaviour hugely increased mortality and evidenced a societal breakdown.
Phase D – the death phase – began. Population increase ceased on day 560. After day 600, no mice survived past weaning. The last conception was documented on day 920. By 1 March 1972, the average age of the colony was 776 days, which was 200 days beyond the average age of mouse menopause. On 22 June 1972, the population was just 122 – 22 male, 100 female – and by May 1973 (1,720 days after colonisation) all the mice were dead.
Autopsy revealed some bizarre things. Of the females aged 334 days at autopsy, only 18 per cent had ever conceived, whereas in the wild they would each have had five or more litters by that age. The male equivalents of these barren females were known as ‘the beautiful ones’. They never sexually approached females and nor did they ever fight other males. They simply ate, drank, and groomed each other, displaying autistic, obsessive tendencies. Almost all of the adult mice in Phase D were these two types, and so the colony died out.
The experiment is fascinating in terms of understanding the post-industrial evolution of humans. Calhoun put the collapse down to overcrowding interfering with the ability of these highly social animals to function. But in 2017, Michael Woodley radically reinterpreted what had happened. 4 Woodley and his team showed that the colony was nowhere near overcrowded when the population growth decline began. They argued that we would expect all health problems, both physical and mental, to be inter-related because they broadly reflect the same thing: high mutational load. This is why left-handedness (a reflection of mutation) is correlated with poor physical and mental health and why autism (a strong marker of mutation) is correlated with poor health.
Secondly, Woodley’s team argue that due to the complexity of the brain, behaviour would be extremely sensitive to mutation accumulation. By extension, in social animals, where behaviour is anyway complex, even small accruals in mutation can lead to pathological forms of behaviour and the rapid breakdown of society. This is, in part, because behaviour is significantly learned in social animals. This means that if mutation interferes with the teaching of some useful behaviour, even those who don’t have what Woodley calls ‘spiteful mutations’ will be impacted. Imagine if, due to some mutation, you get more and more people who believe you shouldn’t kill for meat. As they get larger in number, social pressure to conform will be placed even on those who lack the mutation and they will no longer be taught the despised skill.
Basically, Woodley avers, the mice were evolved to have instincts that allow mice to survive. Every generation, mutant mice would have been born who did not have these instincts: mice with no desire to breed, males with no wish to fight, females with no maternal instinct, females with a male-like desire to fight. However, these mutant mice would have had other mutations – poor immune systems or physical fitness – meaning they wouldn’t have survived to have children. In the Mouse Utopia, of course, they all survived, many of them had children, and, eventually, they were the overwhelming majority of the population. The remnant ‘normal mice’ found that even they were impacted by this change and it got to a point where breeding stopped.
Woodley’s team argue that this ‘Mutational Meltdown’ is happening in the West. There’s no question that mutational load is very high: hence increasing levels of autism, mental illness, allergies, entirely genetic disorders and even lefthandedness. They also document a rise in ‘spiteful mutations’, which cause people to act against their own genetic interests. Examples include mutations that make people want to not have children or heavily delay doing so. And if these people influence society, they can persuade even non-carriers of these genes to act in a self-destructive way.
Mutants can also undermine structures, such as religion, which help to promote group interests. Many evolutionary psychologists agree that religiosity (which is about 40 per cent genetic) is basically a Godmandated means of promoting evolutionary imperatives such as big families, group loyalty, and ethnocentrism; ethnic groups, even European nations, have been shown to be extended kinship networks with clear genetic borders. 5 As a consequence, argues Woodley, modern liberal ideology – far from being an indirect means of genetic preservation – would in fact reflect a sick society’s growing desire to destroy itself.
Does this mean that we are going to die out? Humans are not mice. There’s no scientist controlling us. We are the scientists who have built our own utopia. And Woodley has shown that due to the weak selection in this utopia, we have not just stopped selecting for intelligence, we are becoming less intelligent. 6 IQ is negatively associated with fertility, seemingly because the more intelligent are more efficient users of contraception, and more intelligent women heavily delay or completely reject motherhood.
Accordingly, IQ is going down and some researchers are arguing that, eventually, civilisation will collapse back to a new Dark Age in which natural selection will reassert itself, religion will make a comeback, and humanity will survive. 7 Whatever happened to the utopian mice, humanity’s obituary shouldn’t be written just yet.
LeFt and oPPosIte: John Calhoun in his mouse utopia.