As I explore research on the neurochemical basis of attachment, especially the intriguing studies of oxytocin and monogamous voles, the caveat is always, "A man is not a vole."
How much weight should we give to animal studies? How much can they tell us about human behavior?
Actually, quite a lot. After all, most pharmaceuticals and cosmetics are tested first on animals.
For you naysayers, this 2003 review of the scientific literature of animal models for human sexual functioning found that the results of animal studies are highly applicable to people.
James Pfaus, Tod Kippen and Genaro Coria-Avila write,
Animals possess appetitive and consummatory aspects of sexual
behavior that are homologous and analogous to our own and that are
controlled by similar or identical neurochemical and hormonal systems.
They experience sexual arousal, desire, reward, and inhibition.
Males are excited by females that require some form of courtship or pursuit, and will work hard to obtain even small sexual rewards. Females like to control the initiation and rate of sexual contact. Sexual behavior in males is strengthened with experience, making them less vulnerable to treatments that disrupt sexual responding. The same may occur in females.
From an evolutionary perspective, sexual behavior appears to have similar processes and endpoints for all mammalian species and perhaps for all species that engage in it.
There are some fun anecdotes in the paper: Alcohol lowers the sexual inhibitions of male rats, while what "female rats really like about sex [is] their ability to control its occurrence and rate."