Okay, so now I want you all to watch an experiment. This time it's not about sex appeal and scent. It's about the pitch of your voice. I found this so interesting. Research shows the higher a woman's voice, the more desirable she is to men. Dr. Gordon Gallup of the State University of New York at Albany has been studying how estrogen affects the pitch of a woman's voice during ovulation. And that's what men are unconsciously, you know, they're

unconsciously, it's in their evolutionary DNA to seek out women with whom they're going to be able to pass their genes on. Now this is interesting because you were saying if you're on the pill for a period of time, it inhibits your ability to... Just sniff the guy out. Absolutely. Women on the pill, your body is being tricked into thinking you're pregnant, so you're not ovulating. Which is why the strippers on the pill didn't give out that copulent scent. But also they found in that study I told you about where the women were smelling the T-shirts. That if you're on the pill, or if you're on hormonal contraception, then you actually were attracted to men with similar MHC to you versus different MHC. And the bad news there is that if they have also looked at these couples who have similar MHC, and not only do they have higher levels of infidelity and higher levels of marital discord, but they also have more

fertility issues. Wow. Yeah.

What makes a face drop dead gorgeous? For most of us, the face is where it all begins. Dr. Kendra Schmidt is an assistant professor of Biola Statistics at the University of Nebraska Medical Center. She studies facial sex appeal, and you say there's an equation to measure the perfect face. Right.