1 Biology, Left and Right What is government itself but the greatest of all reflections on human nature? -james madison, 1788 Are we our brothers'' keepers? Should we be? Or would this role only interfere with why we are on earth, which according to economists is to consume and produce, and according to biologists is to survive and reproduce? That both views sound similar is logical given that they arose at around the same time, in the same place, during the English Industrial Revolution. Both follow a competition-is-good-for-you logic. Slightly earlier and slightly to the north, in Scotland, the thinking was different. The father of economics, Adam Smith, understood as no other that the pursuit of self-interest needs to be tempered by "fellow feeling." He said so in The Theory of Moral Sentiments, a book not nearly as popular as his later work The Wealth of Nations. He famously opened his first book with: How selfish soever man may be supposed, there are evidently some principles in his nature, which interest him in the fortune of others, and render their happiness necessary to him, though he derives nothing from it except the pleasure of seeing it. The French revolutionaries chanted of fraternite, Abraham Lincoln appealed to the bonds of sympathy, and Theodore Roosevelt spoke glowingly of fellow feeling as "the most important factor in producing a healthy political and social life." But if this is true, why is this sentiment sometimes ridiculed as being, well, sentimental? A recent example occurred after Hurricane Katrina struck Louisiana in 2005.

While the American people were transfixed by the unprecedented catastrophe, one cable news network saw fit to ask if the Constitution actually provides for disaster relief. A guest on the show argued that the misery of others is none of our business. The day the levees broke, I happened to be driving down from Atlanta to Alabama to give a lecture at Auburn University. Except for a few fallen trees, this part of Alabama had suffered little damage, but the hotel was full of refugees: people had crammed the rooms with grandparents, children, dogs, and cats. I woke up at a zoo! Not the strangest place for a biologist, perhaps, but it conveyed the size of the calamity. And these people were the lucky ones. The morning newspaper at my door screamed, "Why have we been left behind like animals?" a quote from one of the people stuck for days without food and sanitation in the Louisiana Superdome. I took issue with this headline, not because I felt there was nothing to complain about, but because animals don''t necessarily leave one another behind.

My lecture was on precisely this topic, on how we have an "inner ape" that is not nearly as callous and nasty as advertised, and how empathy comes naturally to our species. I wasn''t claiming that it always finds expression, though. Thousands of people with money and cars had fled New Orleans, leaving the sick, old, and poor to fend for themselves. In some places dead bodies floated in the water, where they were being eaten by alligators. But immediately following the disaster there was also deep embarrassment in the nation about what had happened, and an incredible outpouring of support. Sympathy was not absent-it just was late in coming. Americans are a generous people, yet raised with the mistaken belief that the "invisible hand" of the free market-a metaphor introduced by the same Adam Smith-will take care of society''s woes. The invisible hand, however, did nothing to prevent the appalling survival-of-the-fittest scenes in New Orleans.

The ugly secret of economic success is that it sometimes comes at the expense of public funding, thus creating a giant underclass that no one cares about. Katrina exposed the underbelly of American society. On my drive back to Atlanta, it occurred to me that this is the theme of our time: the common good. We tend to focus on wars, terror threats, globalization, and petty political scandals, yet the larger issue is how to combine a thriving economy with a humane society. It relates to health care, education, justice, and-as illustrated by Katrina-protection against nature. The levees in Louisiana had been criminally neglected. In the weeks following the flooding, the media were busy finger-pointing. Had the engineers been at fault? Had funds been diverted? Shouldn''t the president have broken off his vacation? Where I come from, fingers belong in the dike-or at least that''s how legend has it.

In the Netherlands, much of which lies up to twenty feet below sea level, dikes are so sacred that politicians have literally no say over them: Water management is in the hands of engineers and local citizen boards that predate the nation itself. Come to think of it, this also reflects a distrust of government, not so much big government but rather the short-sightedness of most politicians. Evolutionary Spirit How people organize their societies may not seem the sort of topic a biologist should worry about. I should be concerned with the ivory-billed woodpecker, the role of primates in the spread of AIDS or Ebola, the disappearance of tropical rain forests, or whether we evolved from the apes. Whereas the latter remains an issue for some, there has nevertheless been a dramatic shift in public opinion regarding the role of biology. The days are behind us when E. O. Wilson was showered with cold water after a lecture on the connection between animal and human behavior.

Greater openness to parallels with animals makes life easier for the biologist, hence my decision to go to the next level and see if biology can shed light on human society. If this means wading right into political controversy, so be it; it''s not as if biology is not already a part of it. Every debate about society and government makes huge assumptions about human nature, which are presented as if they come straight out of biology. But they almost never do. Lovers of open competition, for example, often invoke evolution. The e-word even slipped into the infamous "greed speech" of Gordon Gekko, the ruthless corporate raider played by Michael Douglas in the 1987 movie Wall Street: The point is, ladies and gentleman, that "greed"-for lack of a better word-is good. Greed is right. Greed works.

Greed clarifies, cuts through, and captures the essence of the evolutionary spirit. The evolutionary spirit? Why are assumptions about biology always on the negative side? In the social sciences, human nature is typified by the old Hobbesian proverb Homo homini lupus ("Man is wolf to man"), a questionable statement about our own species based on false assumptions about another species. A biologist exploring the interaction between society and human nature really isn''t doing anything new, therefore. The only difference is that instead of trying to justify a particular ideological framework, the biologist has an actual interest in the question of what human nature is and where it came from. Is the evolutionary spirit really all about greed, as Gekko claimed, or is there more to it? Students of law, economics, and politics lack the tools to look at their own society with any objectivity. What are they going to compare it with? They rarely, if ever, consult the vast knowledge of human behavior accumulated in anthropology, psychology, biology, or neuroscience. The short answer derived from the latter disciplines is that we are group animals: highly cooperative, sensitive to injustice, sometimes warmongering, but mostly peace loving. A society that ignores these tendencies can''t be optimal.

True, we are also incentive-driven animals, focused on status, territory, and food security, so that any society that ignores those tendencies can''t be optimal, either. There is both a social and a selfish side to our species. But since the latter is, at least in the West, the dominant assumption, my focus will be on the former: the role of empathy and social connectedness. There is exciting new research about the origins of altruism and fairness in both ourselves and other animals. For example, if one gives two monkeys hugely different rewards for the same task, the one who gets the short end of the stick simply refuses to perform. In our own species, too, individuals reject income if they feel the distribution is unfair. Since any income should beat none at all, this means that both monkeys and people fail to follow the profit principle to the letter. By protesting against unfairness, their behavior supports both the claim that incentives matter and that there is a natural dislike of injustice.

Yet in some ways we seem to be moving ever closer to a society with no solidarity whatsoever, one in which a lot of people can expect the short end of the stick. To reconcile this trend with good old Christian values, such as care for the sick and poor, may seem hopeless. But one common strategy is to point the finger at the victims. If the poor can be blamed for being poor, everyone else is off the hook. Thus, a year after Katrina, Newt Gingrich, a prominent conservative politician, called for an investigation into "the failure of citizenship" of people who had been unsuccessful escaping from the hurricane. Those who highlight individual freedom often regard collective interests as a romantic notion, something for sissies and communists. They prefer an every-man-for-himself logic. For example, instead of spending money on levees that protect an entire region, why not let everyone take care of their own safety? A new company in Florida is doing just that, renting out seats on private jets to fly people out of places threatened by hurricanes.

This way, those who can afford it won''t need to drive ou.