Attack of the Killer Mall Rats: Is Sydney becoming a ‘behavioural sink’?

Big business lobbyists and greedy foreigners are turning Sydney into an overcrowded hell hole, says Clive Hamilton. In Saturday’s Sydney Morning Herald Hamilton draws on John Calhoun’s famous rat experiments to argue that Sydney risks becoming a ‘behavioural sink‘ — a city plagued by aggression, social withdrawal and substance abuse.

Back in the 1950s Calhoun wanted to test Thomas Malthus’ theory that "vice and misery impose the ultimate natural limit on the growth of populations." He was particularly interested in vice. In an early experiment Calhoun confined a population of wild rats in a quarter-acre enclosure. With food, shelter and protection from disease and predators, the only real limit on population growth was the rats’ own behaviour. When the population finally stabilised at 150 it wasn’t because of a decline in the birth rate or rising adult mortality — it was due to a breakdown in maternal behaviour. The babies were dying.

Calhoun followed this study with a series of experiments with white lab rats placed in an environment of interconnecting pens each with its own source of food and water. Each time he let the population "increase to approximately twice the number that my experience had indicated could occupy the available space with only moderate stress from social interaction." Again he watched as the vicious Malthusian process unfolded:

The consequences of the behavioral pathology we observed were most apparent among the females. Many were unable to carry pregnancy to full term or to survive delivery of their litters if they did. An even greater number, after successfully giving birth, fell short in their maternal functions. Among the males the behavior disturbances ranged from sexual deviation to cannibalism and from frenetic overactivity to a pathological withdrawal from which individuals would emerge to eat, drink and move about only when other members of the community were asleep.

According to Calhoun, the source of the problem was the rats’ tendency to crowd together into one pen. At feeding times up to 60 or 80 rats would gather in the one place — far too many for them all to be able to eat at once. And most wouldn’t eat unless there were other rats around. Dominant rats would hold their ground while others would withdraw — some passively and others hyperactively probing. Calhoun called these overcrowded areas ‘behavioural sinks.’

Animal behaviour experts disagreed on how to interpret Calhoun’s studies, but social commentators were quick to see parallels with human society. In the 1960s, suburban Americans were all to willing to see overcrowded inner-city neighbourhoods as nests of rats. Commentators thought they saw the same behavioural pathologies in urban tenements filled with blacks and foreign immigrants. Even today newspaper columnists like Colin Wilson of the Times can’t resist the analogy.

When today’s concerned suburbanites gather to fight against high density housing they still urge their politicians to remember the rats. In the United States the eco-friendly advocacy group, 1000 Friends of Oregon confronted these arguments head-on in an article titled ‘The Debate Over Density Do Four-Plexes Cause Cannibalism?‘ As the article explains, "Calhoun’s research, as applied to human settlements, has been largely discredited in the last twenty years."

Since the early 1980s research has shown that Calhoun’s behavioural pathology doesn’t occur among primates like chimpanzees, rhesus macaques and brown capuchin monkeys. Given these findings, it’s a stretch to think that they would apply to human beings. And if crowding really did lead to crime then you would expect crime to be more common in high-density Japan than it is in low-density Australia — but in fact the opposite is true (pdf).

If Hamilton really does think that crowding leads to social pathology, it seems odd that he is protesting against McMansions and car travel. Surely if families move to larger houses with more rooms crowding will decrease. And doesn’t driving to work alone prevent people from crowding together in train stations and on buses? Suburban life seems to be structured to avoid the kind of "excessive social interaction" Hamilton is worried about.

Even when people do crowd together in commuter trains or shopping mall food courts there’s little reason to think that these places are turning into behavioural sinks. The evidence just doesn’t support that idea. No matter how crowed your open plan office becomes your co-workers are unlikely to resort to cannibalism and unwanted mounting behaviour. The urban ‘rat race’ remains a metaphor.

In his SMH piece Hamilton also comes out in favour of increasing Australia’s intake of asylum seekers and political refugees. But strangely he doesn’t cite another of Calhoun’s experiments — one on the effect of forced migration. In 1948 Time Magazine reported:

In the latest Journal of Wildlife Management, Dr. John B. Calhoun, of Johns Hopkins, discusses one such aspect of the rat world: the troubles which refugee rats have to put up with when they emigrate.

Dr. Calhoun took a rat census of several adjoining blocks in Baltimore, and trapped and marked many of the native-son rats. Then he released 112 marked alien rats in the center of the middle block. At once there was social strife. Both native rats and aliens scurried around wildly, invading backyards where none had been seen before. Dogs and humans joined the fray. In the first 18 days there were 31 rat casualties.

Refugee driven race riots? Just wait until Pauline Hanson finds out.


Elsewhere: At LP Phil Gomes remains unconvinced by Hamilton’s arguments. At Catallaxy, Jason Soon and commenters worry about Hamilton’s attitude to wealthy foreigners. Should we use the ‘R’ word?

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18 Responses to Attack of the Killer Mall Rats: Is Sydney becoming a ‘behavioural sink’?

  1. Jason Soon says:

    It’s far, far safer walking late at night in the thick of the densely populated city than almost anywhere else that time of the day. Anyone care to disagree? I’ve been dead drunk past midnight staggering home from Central station with nary a care about getting mugged, something I wouldn’t even consider doing in the suburbs. If we want less crime we should fill the country up and get rid of trading hour regulations.

  2. Jen says:

    Well that proves it. Rats and humans are not the same. – thankyou Don and Happy New Year.

  3. As usual Don, great, great post. Just sayin.

  4. vee says:

    My mice thoughts went more to the Islam countries where you could argue the population density leads to deviant behaviour but the primate experiment seems to indicate otherwise.

    Just to throw in a hint of doubt, we do share over 90% of our dna with mice.

  5. Evil Pundit says:

    Further evidence, if such were needed, that Clive Hamilton is an idiot.

    No wonder the Fairfax flagship papers are sinking, if this drivel is what they have to offer their declining readership.

    One more rat-related phenomenon to watch for — the coming desertion of the Age and SMH by their advertisers as the waters rise.

  6. Chris Lloyd says:

    Rather than taking easy aim at Clive’s sillier comments about rats, zero net immigration and money hungry aspirational migrants, does anyone care to engage with his central points? Which are that Australian capital cities are too crowded, that this imposes infrastructure costs and social costs and that population growth is largely promoted by vested interests.

    Most of Sydney and parts of Melbourne are no longer nice places to live. But they are nicer than Afghanistan which is why people are moving there. Water restrictions in the major cities may be primarily caused by the drought but this would be much less problematic if there were a million less people drawing from the system. Traffic congestion is noticeably worse from month to month in Melbourne’s eastern suburbs. The rail system is standing room only. Yes, this could be fixed by sufficient investment in PT but this is hardly the point. Heritage buildings are being torn down across Melbourne as part of Brack’s 2030 plan which aims to house another million people in Melbourne by 2030. Is anybody here really in favour of such population increase? Was Sydney really so unliveable when it had a million people less?

    Space is a valuable resource. My

  7. “Why do we not sell every non-refugee place to the highest bidder?”

    A suggestion that has often been made by classical liberals, eg Wolfgang Kasper.

  8. Don Arthur says:

    Andrew – If a non-resident can buy the right to live in Australia why not allow residents to sell their rights? Why should these rights belong to the state rather than individuals?

    If other countries did this then it would be possible for a person to sell the right to live in one country and buy the right to live in another.

    I’m not suggesting we do this, but I’m wondering if anyone has seriously considered it.

  9. Don – On Chris Lloyd’s reasoning, it is because the payment is for the costs migrants inflict on those already here, a group someone selling their rights to be in Australia is obviously not part of.

    I haven’t thought about this carefully, so I was not endorsing Wolfgang’s suggestion, merely pointing out that the idea is not new.

  10. Chris Lloyd says:

    I was not intending to argue that migration places should be sold in order to offsaet a cost that migrants impose on the rest of us. I think I was arguing that we should not be giving something away free that we could sell.

    There is no guarantee that the market price of a place would cover the costs of the externalities involved. But I reckon it would. And even if extra immigration has a net advantage to the host country, I can see no reason why we in the host country should not grab a cut of the benefits.

    I am not sure what the marginal cost/benefit of an extra (average) migrant is. At inner city dinner parties, it would be considered poor taste even to pose the question. With most of the costs not being priced and government institutions coy about collecting data based on ethnic background – I am not sure we will ever find out. But the arguments for migration used in the 50s – populate or perish, promoting diversity, shortage of unskilled workers – sure seem to have lost their punch in 2007.

  11. Tony Healy says:

    Richard Freeman also raised this idea. It’s discussed quite well at Mark Thoma’s Economist’s View, where there’s also a link to Freeman’s paper.

    However, because most of the gains from immigration accrue to the immigrants rather than to the residents of destination countries …, there is little incentive for destination countries to ease immigration restrictions. The only way I can think of to increase the receptivity of destination countries to accept more immigrants would be redistribute the benefits of immigration so that a greater share of the benefits flow to natives and a lower share of the benefits to immigrants. The “radically economic”

  12. Jacques Chester says:

    Water restrictions in the major cities may be primarily caused by the drought but this would be much less problematic if there were a million less people drawing from the system.

    They might also be an effect of not allowing freely floating water prices.

  13. Tony Healy says:

    Have you thought that through Jacques? Do you think poor people should go thirsty and also be deprived of facilities for washing and staying clean? I don’t.

    If nothing else, this would rebound on the wealthy by creating disease.

  14. Chris Lloyd says:


    I am all for pricing water, but the price mechanicsm does not remove shortages – except in the narrow economic sense of balancing supply and demand. There would still be a shortage of water in the Sahara regardlses of pricing policy…but economists would say there is no shortage because people have left for lack of water.


    We require rather little water for drinking and a fair bit more for washing. It would be easy enough to have a tiered price – say the current price up to 100L per day per person, 10 times higher for every litre over that – and make the water allotment tradeable. Or would you prefer the current system where my 94 year old beighbour carries buckets of water out to her garden while I sing in teh shower for half an hour?

  15. Tony,

    Water at current prices is a minuscule cost of even poor families budgets. So it’s silly not to price it.

  16. The Devil Drink says:

    Priced water would impact most of all on agricultural and industrial-scale water users; irrigators naturally, but also chemical plants, power stations, processed food manufacturers and users of concrete also. Water is the primary raw material for soft drink makers, distillers and brewers.
    Efficiently price water, by all means, but be prepared for immediate severe hikes in the price of bottled alcoholic and non-alcoholic drinks. In another century, there would have been revolutions.

  17. derrida derider says:

    AS far as having the poor pay more for water goes, Tony, don’t forget that the money raised will make it easier to provide more services.

    If people don’t have enough money to afford lavish water use and we think that they ought to have it then the best solution is to give them more money, not artificially subsidise the water (there’s an exact parallel, BTW, with public housing and with transport concessions).

  18. Tony Healy says:

    Jacques comment that I responded to suggested free floating water prices as a response to high population. In its pure form that would clearly push up water prices to levels that were comfortable for the affluent but stressful and life-threatening to poor people.

    Although I generally endorse the idea of market-driven water pricing, I am highly sceptical of the way such a system would work. Other privatisations of essential monopoly services reveal price gouging and unearned profits to market manipulators, with no consideration for low income people.

    Derrida’s public housing example highlights this. Public housing might be bad, but it’s better than the alternative provided by the commercial market, which is zilch. Also, the high prices generated by the commercial market make subsidies unrealistic. What’s more, that market is so distorted that any subsidies would exacerbate the problem anyway, as evidenced by the effects of the First Home Buyers Grant.

    Free floating prices for water as a response to high population? Definitely not.

    This issue highlights the value of the proposal by Freeman and Kasper, that migration should be subject to market forces.

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