There are lots of reasons one could give for why there hasn't been as much change in the rankings of top players in men's tennis compared to the women's tour. Perhaps there is more competition on the women's side, or maybe more injuries.

Jo-Wilfried Tsonga, who has been just outside the upper echelon of men's players for the past few years, isn't buying either of those reasons. He thinks the discrepancy stems from biological differences.

"You know, the girls, they are more unstable emotionally than us," Tsonga said when asked the issue after his quarterfinal loss to Roger Federer at the Australian Open. "I'm sure everybody will say it's true, even the girls."

It would certainly be interesting to hear what the top women have to say. Some of the game's most dominant players, like Maria Sharapova and Serena Williams, have been sidelined by serious injuries. Is that simply coincidental, or is there a biological explanation for that?

Tsonga seems to take the latter approach.

"It's just about hormones and all this stuff," Tsonga said. "We don't have all these bad things, so we are physically in a good shape every time, and you are not. That's it."

(H/T to Game On!)