The National Post reports in its Wednesday, Feb. 6, edition that when Dr. Jorge Chavarro's colleagues started investigating marijuana's effects on sperm, they had every reason to believe weed would prove detrimental to "testicular function," because other studies had said it to be so. The Post's Sharon Kirkey writes that instead, they found the opposite. Men who had ever smoked marijuana had significantly higher sperm concentrations and sperm counts, as well as higher testosterone levels, compared with men who had never smoked weed. Overall, the sperm of past and current marijuana users seemed to be of superior quality. "These findings are not consistent with a deleterious role of marijuana smoking on testicular function as initially hypothesized," Dr. Chavarro and his colleagues report this week in the journal Human Reproduction. Previous studies -- the majority of them in rats, but a few in human males as well -- have linked heavy pot use with a slump in sperm production. The men in the new study, however, were smoking, on average, two joints a week. Mr. Chavarro cannot fully explain the unexpected findings.