Yeah, but a few paragraphs later, we have this:

"According to Lokeshwar, potential causes for these declines could be increased obesity/BMI, assay variations, diet/phytoestrogens, declined exercise and physical activity, fat percentage, marijuana use, and environmental toxins."

My personal, totally unsupported hypothesis: society is simply kinder and gentler now. As evidenced by the high testosterone in prison populations, this hormone responds to environmental threats of potential violence.