Hey there!

From a lipstick advertisement:

"Lips are sensuous, sexy, pouty and kissable. It's the erotic zone, the most vulnerable and the most expressive feature of a woman. It doesn't matter that you have thin lips or thick. You can make your lips attractive if you know how to treat them right."

From a science article on apes:

"A large and nearly hairless patch of skin around the genital area of female apes (the vulva) becomes very prominent (and quite visible) when they are in estrus. These areas swell with fluids and turn bright pink or red due to hormonal changes that occur in preparation for ovulation. Males become highly attentive to the females at this time."

Is there a connection? ~ Yes, indeed . . .

Because women are "clothed" and no longer "knuckles to the ground" like the apes, their vulvae are not visible. But a woman can convey an equally effective (vulval) message by accentuating the redness, fullness and moisture of her oral lips. By doing so, she can induce men to believe (at a pschologically unconscious level) that they are looking at her vulva. If her lips are reddened, glossy and engorged, it vividly suggests to them that she is ovulating and that she is sexually receptive (provided modern day men are as acutely perceptive as male apes!)