New research suggests that aggressive traits in professional investors may translate into lower returns, according to recent article in The Economist.

A recent study analyzed over twenty years of data on hedge-fund returns and facial images collected from Google (wider faces, the article reports, is considered a proxy for higher testosterone levels) to evaluate the relationship between the hormone (associated with competitiveness and risk-taking) and investment performance. The study authors found that “fund managers with wider faces…tend to trade more frequently, invest in riskier securities and hold onto losing bets longer.” The data showed that, during the period between 1994 and 2015, high-testosterone fund managers…underperformed low-testosterone ones….by 5.8% per year.”

The article concludes: “If emotions inhibit traders’ ability to think rationally during market booms and busts, investors might be better off entrusting their money either to static index funds, or to trading algorithms without any emotions at all.”