The Spread of Goodness

I like Jonah Lehrer’s writing. Here’s a recent post on how altruism could spread, based on research by Nicholas Christakis and James Fowler, authors of Connected: The Surprising Power of Our Social Networks and How They Shape Our Lives.

There’s something strange about watching life unfold as a social network. It’s easy to forget that every link is a human relationship and every circle a waistline. The messy melodrama of life–all the failed diets and fading friendships–becomes a sterile cartoon.

In their latest paper, published this week in PNAS, Christakis and Fowler re-analyzed an earlier set of experiments led by Ernst Fehr and Simon Gachter, which investigated “altruistic punishment,” or why we’re willing to punish others even at a cost to ourselves.

Christakis and Fowler demonstrate that, when one of the students gave money to help someone else – they were cooperating – the recipients of that cash then became more likely to give their own money away in the next round. (Every unit of money shared in round 1 led to an extra 0.19 units being shared in round 2, and 0.05 units in round 3.) This leads, of course, to a cascade of generosity, in which the itch to cooperate spreads first to three people and then to the nine people that those three people interact with, and then to the remaining individuals in subsequent waves of the experiment.

The paper itself is filled with optimistic sentences, but it’s worth pointing out that 1) selfishness is also contagious and 2) there’s a big difference between lab experiments played with strangers and the messy social networks of real life. That said, altruistic cascades like this make me happy:

We report a chain of 10 kidney transplantations, initiated in July 2007 by a single altruistic donor (i.e., a donor without a designated recipient) and coordinated over a period of 8 months by two large paired-donation registries. These transplantations involved six transplantation centers in five states. In the case of five of the transplantations, the donors and their coregistered recipients underwent surgery simultaneously. In the other five cases, “bridge donors” continued the chain as many as 5 months after the coregistered recipients in their own pairs had received transplants. This report of a chain of paired kidney donations, in which the transplantations were not necessarily performed simultaneously, illustrates the potential of this strategy.


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