Chapter 1
Chapter 2
Chapter 3
Chapter 4
Chapter 5
Chapter 6
Chapter 7
Chapter 8
Chapter 9
Chapter 10
Chapter 11
Chapter 12
Chapter 13
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Oxytocin has been known for years, but not as a brain peptide. Here we see them milking cows the old-fashioned way. Each squeeze of a teat is followed, a few seconds later, by a squirt of milk. Oxytocin does that. A squeeze (or a suckle)
is sensed by
the hypothalamus, which sends a pulse of oxytocin down to the pituitary
and into the blood. This acts on the udder (or breast, in humans)
which squirts out the milk. .... Some
lactating women have been known to squirt milk across the room!
Next door, there’s a ewe giving birth. Her womb (uterus)
contracts hard in waves to expel the newborn lamb. Oxytocin
again. Women near term can be induced to give birth by being
infused with oxytocin (more usually, with an artificial peptide
closely resembling it). As the baby, or little lamb, snuggles up
to its mother, more oxytocin ensures a good supply of milk.
How extraordinary, then, that it took so long for its role in the brain to be discovered – a role that fits so well with its other actions. For good mothering needs not only a successful birth, and an efficient supply of milk, it also needs the mother to be ‘maternal’. That is, to be motivated to care for her young (provide food, warmth, protection, a shelter) and to make sure the baby stays close, and to look for it if it strays. To do that, the limbic system cleverly makes the baby a prized object, something the mother doesn’t want to lose. Its called ‘attachment’ or ‘bonding’ or ‘motherly love’ and oxytocin, a little peptide of only eight amino-acids, may be an essential chemical signal responsible for it………
A human mother is attached to her little child; she also bonds with her mate (partner) and both feel strong affiliations to their parents. In each case, there is a strong attachment to a particular person (which may exclude others). Three words – bonding, attachment, affiliation - with essentially the same meaning. There’s a fourth, which you won’t find mentioned much in the neuroscientific literature, because neuroscientists find it troubling. It’s called love, and poets have no problems with it.
I am not so concerned here with the psychological aspects of love, on which there is a literature, as with the biological functions of love and its neural basis. Love, attachment, whatever you call it, implies that a particular person becomes special, in that social interaction (and usually proximity) is rewarding, that loss (temporary or permanent) is both feared, avoided and, if it happens, is treated as a serious adversity, and great efforts are made to rectify this loss or deficit. You may recognise this description as one that could apply to more mundane requirements, like food, water, adequate heat and so on. Just as there are two levels of understanding for, say, hunger (what is its function? how does it happen?) so there are for love. The biological function of love (its role in survival) lies in the fact that attachment implies an individually-distinct interaction……….
Scientific and literary quotes.