found in the cellular slime moulds, such as Dictyostelium mucoroides. These protists live as individual amoebae until starved, at which point they aggregate and form a multicellular fruiting body in which some cells sacrifice themselves to promote the survival of other cells in the fruiting body. Selective investment theory proposes that close social bonds, and associated emotional, cognitive, and neurohormonal mechanisms, evolved in order to facilitate long-term, high-cost altruism between those closely depending on one another for survival and reproductive success. Such cooperative behaviors have sometimes been seen as arguments for left-wing politics such by the Russian zoologist and anarchist Peter Kropotkin in his 1902 book Mutual Aid: A Factor of Evolution and Moral Philosopher Peter Singer in his book A Darwinian Left. Neurobiology Jorge Moll and Jordan Grafman, neuroscientists at the National Institutes of Health and LABS-D'Or Hospital Network (J.M.) provided the first evidence for the neural bases of altruistic giving in normal healthy volunteers, using functional magnetic resonance imaging. In their research, published in the Proceedings of the National Academy of Sciences USA in October 2006, they showed that both pure monetary rewards and charitable donations activated the mesolimbic reward pathway, a primitive part of the brain that usually responds to food and sex. However, when volunteers generously placed the interests of others before their own by making charitable donations, another brain circuit was selectively activated: the subgenual cortex/septal region. These structures are intimately related to social attachment and bonding in other species. Altruism, the experiment suggested, was not a superior moral faculty that suppresses basic selfish urges but rather was basic to the brain, hard-wired and pleasurable. One brain region, the subgenual anterior cingulate cortex/basal forebrain, contributes to learning altruistic behavior, especially in those with trait empathy. The same study has shown a connection between giving to charity and the promotion of social bonding. In fact, in an experiment published in March 2007 at the University of Southern California neuroscientist Antonio R. Damasio and his colleagues showed that subjects with damage to the ventromedial prefrontal cortex lack the ability to empathically feel their way to moral answers, and that when confronted with moral dilemmas, these brain-damaged patients coldly came up with "end-justifies-the-means" answers, leading Damasio to conclude that the point was not that they reached immoral conclusions, but that when they were confronted by a difficult issue – in this case as whether to shoot down a