From the NY Times on bonobos and female arousal:
"She found footage of bonobos, a species of ape, as they mated, and then, because the accompanying sounds were dull — “bonobos don’t seem to make much noise in sex,” she told me, “though the females give a kind of pleasure grin and make chirpy sounds” — she dubbed in some animated chimpanzee hooting and screeching. She showed the short movie to men and women, straight and gay."
(from the same article)
"These researchers and clinicians are consumed by the sexual problem Sigmund Freud posed to one of his female disciples almost a century ago: “The great question that has never been answered and which I have not yet been able to answer, despite my 30 years of research into the feminine soul, is, What does a woman want?”"