Birds chirp to attract their mates. Similarly, women’s voices get higher and more feminine to accomplish the same task. This is especially true when they are near ovulation, according to ScienceDaily . This is an unconscious attractor factor, and usually becomes apparent when women say simple sentences, and not plain vowel sounds.
The study was conducted by UCLA professors Gregory A. Bryant and Martie G. Haselton, both communication specialists. They found that women only change their voices in social situations relevant to fertility, and they might only do it in public. This relates to youth, and so men have become attracted to these higher voices.
The thing to take away from this article is that even humans have peculiar mating habits – and who knows, you could unconsciously be falling prey to them.