Can the common brain parasite,Toxoplasma gondii, influence human culture?

Abstract

The latent prevalence of a long-lived and common brain parasite, Toxoplasma gondii, explains a statistically significant portion of the variance in aggregate neuroticism among populations, as well as in the 'neurotic' cultural dimensions of sex roles and uncertainty avoidance. Spurious or non-causal correlations between aggregate personality and aspects of climate and culture that influence T. gondii transmission could also drive these patterns. A link between culture and T. gondii hypothetically results from a behavioural manipulation that the parasite uses to increase its transmission to the next host in the life cycle: a cat. While latent toxoplasmosis is usually benign, the parasite's subtle effect on individual personality appears to alter the aggregate personality at the population level. Drivers of the geographical variation in the prevalence of this parasite include the effects of climate on the persistence of infectious stages in soil, the cultural practices of food preparation and cats as pets. Some variation in culture, therefore, may ultimately be related to how climate affects the distribution of T. gondii, though the results only explain a fraction of the variation in two of the four cultural dimensions, suggesting that if T. gondii does influence human culture, it is only one among many factors.

Do differences in Toxoplasma prevalence influence global variation in secondary sex ratio? Preliminary ecological regression study

“…Prevalence of latent toxoplasmosis in women of childbearing age in various countries. Third column shows prevalence (%) adjusted to a standard age of 22 years to account for variation in childbearing age across countries using the formula Prevalence adj = 1 -(1 -Prevalence)^(22/childbearing age) (Lafferty, 2006). Year in which the given study has been carried out is shown in the fourth column, the fifth column states the number of women in the sample and the last one gives sex ratio at birth (SRB).…”

Toxoplasma gondiiinfection, from predation to schizophrenia: can animal behaviour help us understand human behaviour?

“…Even an equivalent of the fatal feline attraction phenomenon observed in infected rats (Berdoy et al, 2000) has been identified in humans, where T. gondii-positive humans showed altered questionnaire responses to the odours of the domestic cat (and of the brown hyena) (Flegr et al, 2011). Such subtle changes in human behaviour and personality in response to latent T. gondii infection at the individual level have even been proposed to alter the human aggregate personality at the population level (Lafferty, 2006). Latent T. gondii infection in the human host may, furthermore, in a small number of cases, have substantial health implications.…”

Infectious personalities: behavioural syndromes and disease risk in larval amphibians

“…Behaviour and infection are intimately linked because parasites can affect behaviour, perhaps even influencing human personalities and contributing to cultural differences [8], and many individual host behaviours have been separately shown to impact chances of infection [9,10]. However, very few studies of behavioural syndromes have examined whether animal 'personalities' predict susceptibility to parasitism [11,12], and none have done so experimentally.…”