Two Carleton biologists released a study May 7 linking national IQ to parasites.

Christopher Hassall and Thomas Sheratt began work after discussing a paper on spatial variation in IQ, Hassall said in an email.

The study shows that people living in warmer climates often have a lower IQ because a greater amount of parasitic infections exist in places with higher temperatures. These findings support an earlier study by researchers at the University of New Mexico (UNM).

Hassall and Sherratt said an earlier study had one major flaw — it neglected spatial autocorrelation, which takes into consideration that certain data results are similar due to geographical proximity.

“We realized that the psychologists had been treating their analysis as a psychological problem, whereas we saw that it was clearly an ecological problem,” Hassall said.

Their study was largely a statistical one to show the importance of controlling for spatial autocorrelation and how to do a better analysis of IQ variations among countries, Hassall said.

Key factors taken into consideration for the study were distance from central Africa, temperature, parasites, nutrition, education, and GDP.