Infection from a globally prevalent parasite could increase a person’s likelihood of pursuing entrepreneurial and business-related activities, new research at the University of Colorado in Boulder finds.

In a study of 1,495 undergraduate students, CU researchers found that students who tested positive for Toxoplasma gondii were 1.4 times more likely to major in business and 1.7 times more likely to pursue a pursue a management and entrepreneurship emphasis. In an additional survey of 197 adult professionals attending entrepreneurship events, infected individuals were 1.8 times more likely to have started their own businesses compared with other attendees.

The researchers also compiled national statistics from 42 countries over the past 25 years and found that T. gondii infection prevalences — which range from 9 percent in Norway to 60 percent in Brazil — proved to be a consistent, positive predictor of entrepreneurial activity, even when controlling for relative national wealth and opportunity factors.

T. gondii, which naturally reproduces in wild and domestic cats, infects an estimated 2 billion people worldwide. While human infections often lack acute symptoms, T. gondii has been correlated with impulsive behaviors and the increased risk of car accidents, drug abuse, mental illnesses and suicide.

Because the parasite needs a cat to reproduce, any changes in host behavior that make them more likely to get eaten by a cat are hypothesized to benefit the parasite.

The study, published in the journal Proceedings of the Royal Society B, explores the role transmissible microbes could play in affecting human decision making and cultural behaviors on large scales.

“As humans, we like to think that we are in control of our actions. But emerging research shows that the microorganisms we encounter in our daily lives have the potential to influence their hosts in significant ways,” said Pieter Johnson, co-lead author of the study and a professor in the Department of Ecology and Evolutionary Biology at CU.

Other examples of such parasite-host interactions abound in nature, including the Ophiocordyceps unilateralis fungus that hijacks carpenter ants’ brains and compels self-destructive behavior. In humans, the microbiome in the digestive system contains bacteria that have been linked to mood, diet and immune system functions.

Economics research has historically emphasized the importance of rationality in explaining human decisions, with individuals considering benefits and risks before acting in their self-interest. Exposure to T. gondii could nudge individuals toward higher risk, higher reward activities and deviating from economic theory, the researchers discovered.

The study found that nations with a higher infection prevalence saw a lower fraction of respondents cite a “fear of failure” as a deterrent to a new business venture. But that’s not to say that all of those businesses will work out or that T. gondii necessarily deserves credit or blame for any individual outcome, the researchers said.

“We can see the association in terms of the number of businesses and the intent of participants, but we don’t know if the businesses started by T.gondii-positive individuals are more likely to succeed or fail in the long run,” said Stefanie K. Johnson, co-lead author of the study and an associate professor at the Leeds School of Business at CU. “New ventures have high failure rates, so a fear of failure is quite rational. T.gondii might just reduce that rational fear.”

The researchers said the study is correlational, rather than causal, in nature and that individuals pre-disposed to high-risk behavior could be more likely to be both entrepreneurial in their attitudes and exposed to T. gondii through animal contact.

“Infectious diseases have strongly shaped human history and culture over millions of years,” Pieter Johnson said. “Today, we like to believe our decisions and destiny are ours alone, but the contributing roles of our microscopic companions are increasingly apparent.”