100 CHAPTER FOUR
work brings together a set of scientific disciplines and research agendas,
assumptions about evolution and gender roles, polypeptides and recep-
tors, the bodies of human and nonhumans, and their relations to enact
and measure attachments. While this research is being applied to explain
reproductive kinship, the heteronormativity of this work is not inevitable;
neurobiological systems can be understood otherwise.
Oxytocin and Social Neuroscience
In 1909 Henry Dale treated the uterus of a pregnant cat with an extract taken
from the human pituitary gland, causing her to begin labor. He named the
substance oxytocin (from ancient Greek, meaning “quick birth”). A year
later, Ott and Scott described its role in milk- ejection in mammals. In 1953
oxytocin was the first polypeptide, or compound of multiple amino acids,
to be sequenced and biochemically synthesized. Oxytocin and a similar
polypeptide, arginine vasopressin, are now known to be hormones made
in the brain by cells in the hypothalamus.^1 They are stored in the axon
terminals (endings) of neurons that extend from the hypothalamus to the
posterior pituitary gland, located at the base of the brain, where they are
released into the bloodstream for peripheral circulation throughout the
body. They also are released from collateral (branching) axons of those
neurons or through distinct neurons to other parts of the brain, where
they act as neurotransmitters; through this separate pathway, they are now
thought to influence affect and behavior. Cells respond to the presence of
neurohormones when they possess receptors for that hormone; for exam-
ple, as Dale found, in female mammals the binding of oxytocin to receptors
in the uterus during the final phase of pregnancy causes its smooth muscles
to contract, facilitating parturition. (Synthetic oxytocin is commonly ad-
ministered to induce labor in medicalized childbirth.) Oxytocin also facil-
itates the “let- down” reflex of the mammary glands in lactation. For many
decades, these were its only known effects.
The scientific treatment of oxytocin is no longer limited to the mechan-
ics of female reproduction. Oxytocin is now thought to be active in both
sexes, implicated in a range of dynamic bodily systems and “widely distrib-
uted through the body and brain” (Feldman 2012, 380). It remains heavily
identified with the maternal body (whereas vasopressin is treated as a male