Therefore, because wild mice are so short-lived, mice are not 'built to last' and have the reputation of being unusually-prone to produce new deleterious mutations (and are therefore extremely prone to cancer, and susceptible to carcinogens - which is why mice are used to test for carcinogens). The reason why mouse utopia might produce so rapid and extreme a mutation accumulation is that wild mice naturally suffer very high mortality rates from predation. So the bizarre behaviours seen especially in Phase D - such as the male 'beautiful ones' who appeared to be healthy and spent all their time self grooming, but were actually inert, unresponsive, unintelligent, uninterested in reproduction - are not adaptations to crowding, but maladaptive outcomes of a population sinking under the weight of mutations. The Mouse Utopia experiment is usually interpreted in terms of social stresses related to 'over-population' crowding - generating pathological behaviours and a loss of the will to live.īut Michael A Woodley suggests that what might be going on is mutation accumulation, and deleterious genes generating a wide range of maladaptive pathologies, incrementally accumulating with each generation and rapidly overwhelming and destroying the population before any beneficial mutations could emerge to 'save the colony from extinction.
The last conception was about day 920, after which there were no more births, all females were menopausal, the colony aged and all of them died. Terminal Phase - population declining to zero. Emergence of many pathological behaviours. Phase D - days 560-920 population stagnant with births just matching deaths. Phase C - from day 315-560 population growth abruptly slowed to a doubling time of 145 days. Phase B - up to day 315 - exponential population growth doubling every 55 days. Phase A - 104 days - establishment of the mice in their new environment, then the first litters were born. What happened is described by the author: The idea was that four breeding pairs of mice were allowed to reproduce freely in a 'utopian' environment with ample food and water no predators no disease comfortable temperature, conditions and space. The so-called Mouse Utopia experiment was conducted from 1968 by John B Calhoun
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