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Cats have been pets or living around humans for around 10,000 to 12,000 years ago. This first began in the fertile crescent, a moon-shaped grouping of countries that include the Levant, Mesopotamia, and Ancient Egypt. In modern geography, this includes countries like Lebanon, Turkey, Israel and Iraq.

As nomadic humans left Africa, their turning to agriculture and dairy farming happened initially in this fertile crescent. Farming grain meant granaries, and thereby rodents that were attracted to a new readily accessible food source. But with food sources come a biological truism—a food chain. It’s the sobering set piece of life—the hunter for food becomes the hunted. Into this world entered happy felines with a disregard for rodent life or any respect for the scavenging utility of their would-be victims.

In the 1950s in New Zealand, Toxoplasma gondii, a protozoan parasite was found to be the cause of sheep abortions. Even in pregnant women, we now know that when mothers are infected in the first trimester, about 15–20% of babies become infected, compared to about 30% in the second trimester. It can lead to brain or eye problems in the newborn. How did sheep in New Zealand get this parasite?

This dastardly parasite had been discovered by scientists in North Africa and Brazil a century ago. However, the finding of this parasite in new world New Zealand in the 1950s led to a meticulous search for a definitive host. In the 1960s, cats were finally identified as the culprit. T. gondii is shed in the faeces of infected cats and is a source of infection for many intermediate hosts like humans. This explained Toxoplasma infections in herbivorous animals as well as people with a vegetarian diet. Today we know that the cat-human cohabitation has led to approximately a third of all human beings of the world i.e., over 2.5 billion people are infected globally! Crazily, latent toxoplasmosis has been linked to behavioural changes and implicated in suicides and driving accidents! These changes have been attributed to the parasite’s ability to synthesize tyrosine hydroxylase, an enzyme involved in the production of dopamine. The parasite also affects serotonin, glutamate and other neurotransmitters. We know that if dopamine-mediated neurotransmission is affected, it leads to more addictive and obsessive behaviours. And of course, serotonin is linked to mood changes. Therefore, increasingly scientists have been studying the psychological aspects of underlying and undiagnosed latent Toxoplasmosis.

Now let’s look at the science behind a recent study that you can read for yourselves. Firstly, latent toxoplasmosis is known to cause longer response times in part of the population, and such response times are easy to account for in research methodology. Another interesting scientific fact about this parasite is that people with Rhesus-negative blood types become slower when afflicted by toxoplasmosis, while Rhesus-positive individuals do not experience a change in response times. Using large population samples, and accounting for all these variables, researchers not only looked at behavioural changes previously reported in the literature for infected individuals but also searched for new insights on the any long term effects of latent infection. Other than the psychological effects, they also investigated socioeconomic consequences such as annual income and unemployment probability. Their findings: Other than the already known psychiatric diseases and risky behaviours, latent toxoplasma infection causes, on average, a reduction in yearly income of 2500 British Pounds, and an 11% increase in unemployment! Science can be a mystery when researchers’ probing intellect is combined with middle-aged subjects who may be suspicious of their motives. When I first looked at the project it looked overproduced, but the results appear grounded in good methodology and not gimmicky, even with this cat-astrophic conclusion.

Therefore, if you find you child slacking off after school or university studies and not finding or keeping a job, they may have a moggy excuse.

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