Finding a home on the range may quiet men’s raging hormones, a team of Harvard University anthropologists has found.

The study, which will soon be published in the journal Human Reproduction, used saliva samples to test whether male testosterone levels varied according to the participants’ social relationships. They found married men have significantly lower testosterone levels than single men.

Two professors and three graduate students ran the experiment, which involved 58 men split into three categories—single men not currently in a relationship older than three months, married men with no children and married men with children no older than four years old.

The researchers found that the difference between testosterone levels increases throughout the course of the day.

They took four daily saliva samples from each of the men—twice in the morning and twice in the evening.

In the evening, the measurements were significantly lower for married men in comparison to single men, with fathers having the lowest levels of testosterone. In contrast, testosterone levels for all the men were effectively the same in the morning.

According to Peter Gray, a graduate student who took part in the research, this study is only the “starting ground.”

The results, he said, leave open the question whether men with lower testosterone levels are more likely to be married and have children or whether marriage and children actually cause testosterone levels to decline.

A similar study Gray conducted in Kenya came up with contrary conclusions, finding no difference in testosterone levels between married monogamous men and single men.

In fact, Gray said, men in polygamous marriages actually had higher levels of testosterone.

He said these findings may be due in part to cultural differences in marital customs.

“Some unmarried men in Kenya were previously married and divorced,” Gray said. He said the Kenyan men, on average, had more “complicated” marital relationships than the singles he tested in Boston.

Gray is currently researching whether the age of a man’s youngest child has an effect on his hormone levels.

He is also conducting a study in which he tests fathers who spend two days with their children followed by two days without child contact.

Further research might be spurred by the current use of testosterone as a steroid supplement, Gray said. This has prompted new studies to question how testosterone supplement effect men’s relations with their wives.

“There will be a lot more data in five months,” Gray said.