Sexuality of the sexes

Something that I found very interesting was the different sexual desires of the different character in the novel. Shira is totally locked up and scared of sex toward the beginning of the novel while her grandmother has had so many sexual encounters that she cannot count them all. Similar to Shira is Avram since his wife passed on his sexual abilities appear to have vanished with her. Gadi appears to be stuck in his love life as a teenager as he surrounds himself with a crowd of them while targeting them as sexual objects. Last but not least there is Yod, who has a new sexual hunger that appears to be unquenchable. That Yod is Malkah's last sexual encounter and Shira's sexual reawakening is important, like the dying of an old era to make room for a new one.
Beyond the differences of the apparent sexes, Yod the cyborg is more interested in sexual encounters than any of the humans. I do not think it follows his same desire to learn about the world around him. If that were the case he would just want to experience it once. Instead he desires Shira, pursues her, for another sexual experience. He is addicted to pleasure, just as a human beings can be. As Russ mentioned, there is a line on page 93 where Yod says "I am conscious of my existence". Since that is Descartes major qualification for being a human being, I am a little confused as to what makes Yod not a human being. His sexuality would therefore be rational, and all his desires to learn, even to kill sometimes. This thought is not yet complete, but it is hard to define what is a human being, and I'm not sure that I am prepared here to give a complete definition of one. Anyone have any additional thoughts?