The Science of Heartlessness

From the book "Quirk," by way of Salon, discussing the role of oxytocin in empathy:

[S]tudies are finding that oxytocin can increase the amount of money people will donate to a charity. One study in particular lent credence to the time honored method charities use to pull money from magazine readers: Feature a woebegone child in your advertisement. In the study, researchers had subjects watch a tearjerker film of a father talking about his son's brain tumor. They sampled subjects' blood before and after the film. Following the film the blood was awash in oxytocin, and their donations to charity rose 47 percent, compared to those of subjects who saw a film of the same father talking about a trip to the zoo. The tearjerker technique was more effective on women than men. Experiments wherein people sniff oxytocin to bolster the chemical in their brain show that the chemical may work in two ways. It may operate first by dampening our natural fear of one another. Oxytocin is very active in the amygdala, which monitors the world for danger. Extra oxytocin fights fear. Then, with that terror out of the way, perhaps it's easier to read another person's emotions and relate to them. People dosed with oxytocin make more direct eye contact, and they are better at describing the emotions portrayed on another's face. So extra oxytocin also helps us to empathize.

I found this description of mother vs. baby refreshingly frank, although it certainly is nothing new:

[A] mother -- every mother, whether snake, skunk, or sheep -- has biological aspirations above and beyond an infant. In her DNA she dreams of launching not one, but a dozen offspring down the river of time. And to do that she has to watch out for her own health and welfare.

All mothers and their infants engage in a battle over this issue, from the moment of conception. It is in the offspring's best interest to drag every nutrient and calorie it can absorb out of its mother's body. It is in the mother's best interest to hold something back so that she can raise future offspring. This battle continues after birth. An infant denied the opportunity to nurse does not quit without a fight. She'll let loose wails that in earlier times could attract deadly predators.

But no matter how sympathetic a mother might be, the infant won't gain the upper hand in this contest. Starvation remains a real threat to humans today, and the photographs that come out of refugee camps testify to the importance of motherly selfishness. Still strong enough to walk, mothers embrace their dying children. I'm sure they wish they could nurse their children, but evolution has outfitted them with bodies that will not permit it. When a female's body fat drops below a certain point, she can continue to empathize with her child's pain, but her body refuses to sympathize: Her body stops producing milk. And how could it be otherwise? Why would evolution reward a body that would give its last calorie to an offspring, then die and leave the offspring to starve alone? The offspring of such sympathetic mothers don't survive, and neither do the genes that would make a person so disastrously generous.

But neither could evolution produce mothers who would abandon an infant at the first sign of hardship. Evolution rewards those mothers who invest in their existing offspring but guard their ability to have more children in the future.
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Why would that be? Why does evolution perpetuate both the pushovers and the pushers? Well, a personality that's low in sympathy or empathy is not a heartless block of stone. She just isn't so quick to assume the feelings of others. She does a better job of maintaining her boundaries and keeping a steady eye on her own future. Undistracted by life's melodramas, she's more likely to focus on facts and figures.