A cottage industry has grown in recent years around theories purporting to explain how our brains produce empathy, morality, and good will.

Like Darwin, Wilson begins with the animals, specifically bees, which, when their colony splits by swarming, send out scouts to search out a new nest cavity. Miraculously, when the individual scouts return, each having visited a cavity or two at most, and therefore lacking the requisite big picture to "argue" their case, a collective decision about the best option is nonetheless made based on their dancelike interactions. This collective process is uncannily similar in pattern to the one observed between individual neurons in the brains of rhesus monkeys that are trying to determine the principal direction of movement of haphazard dots on a screen. The "group mind" of the bees seems to work in almost identical ways to the single, multimillion-neuron mind of the monkey.

And that is not all. Before sunset on the African plains, female buffaloes determine where the herd will graze next by pointing their heads distinctively in a certain direction; somehow each nod is integrated and the direction with the most "votes" chosen. Pelicans form half-circles, paddling in unison to trap coastal fish. Tadpoles communicate via surface waves to make collective decisions about which food sources to tap. Even bacteria use quorum sensing to coordinate gene expression according to the density of their population. How does such seemingly incredible group functionality come about? According to Wilson, the answer can be found in a few basic evolutionary principles.

All of evolution, he argues convincingly, can be stated on one foot, akin to Rabbi Hillel’s condensation of the Bible ("Do unto others as you would have them do unto you"). It goes like this: "Selfishness beats altruism within groups. Altruistic groups beat selfish groups. All else is commentary." Here’s the reason: Since natural selection is based on relative fitness rather than absolute fitness, all that matters for an organism is that it be in better shape than its neighbors; jumping highest or eating the most in an absolute sense is meaningless. Except that "putting out" for the group, in the form of costly cooperation or outright sacrifice, necessarily reduces the relative fitness of the individual.

So there is a conflict: Should one look out for oneself or the tribe? The conflict is complicated by the fact that cooperative groups do better than less altruistic ones. Group functionality will therefore almost invariably evolve by natural selection working between groups rather than within them. The organism-like quality of groups of bees and buffaloes and pelicans and tadpoles and bacteria have the successful suppression of individual urges to thank.

Figuring out the mechanisms that give birth to group cohesion by blocking individual selfishness is therefore an important evolutionary agenda. It helps to explain the origin of life, how single cells came together to form multicellular creatures, and why, among social insects like bees, ants, wasps, and termites, but also mammals like the blind African mole rat, entire castes forgo reproduction, devoting their lives instead to the greater good. It is also a key to fighting cancer. There is a tradition, going back nearly a century, of biologists’ searching out the secrets of the "superorganism," and D.S. Wilson has been one of its prominent modern practitioners.

It's fascinating but there's still a lot to figure out.

All we need to do to "increase the performance of the brain’s neuronal circuitry" is to create the right environments—small classrooms, fewer vagrants walking the streets, less corruption and bullying, more women in positions of power, after-school games, curfews, self-aware politicians—and the sought-after physiology will appear. With the right amounts of oxytocin, vasopressin, and corticotropin-releasing hormone, a benevolent brew baked into our brains by evolution, the switch will be flicked on, he writes, so as "to help us do the job of making an ethical decision."

There’s nothing wrong with offering a guess and calling it a theory; the history of science teaches that this is a preferred method for gaining insight into ourselves and the world. Unfortunately, many popularizers of brain research slip imperceptibly between arguing for theoretical possibilities and stating them as fact. Many lack humility. You could do worse than arming yourselves with Sally Satel and Scott O. Lilienfeld’s Brainwashed: The Seductive Appeal of Mindless Neuroscience (Basic Books, 2013)to train yourself to recognize what has been termed "brain overclaim syndrome" when you see it. As reductionist caricatures infiltrate the medical, educational, and legal systems, we should all be on the lookout.

Not that we haven’t learned a great deal in recent years about the neurochemistry of behavior. Oxytocin, for one, is a fascinating little molecule. This tiny neuropeptide, which is more than 700 million years old, was gradually co-opted from regulating water and mineral levels in the bodies of terrestrial animals to being involved in the function of the placenta and the workings of lactation, in uterine contractions, and in suckling and attention in female mammals. Evolution being the master tinkerer, the ambit of such caring behavior was eventually extended from kin to kith.

We now know that complex social behaviors, whether pair bonding or promiscuity, are strongly related to the density of receptors for oxytocin in the brains of voles, marmosets, titi monkeys, and the California deer mouse. In humans, cocaine-using mothers have lower levels of oxytocin and display less maternal behavior, while healthy fathers injected with the molecule via a nasal spray show markedly more affection toward mothers and kids. Even the business world has taken notice: Subjects administered sniffs before playing an economic game in which trust plays a decisive role in success were found to be more trusting in others and hence more successful. Various companies are already advertising oxytocin nasal spray on the Internet.

This is fascinating stuff, but it’s far from a Holy Grail. For one thing, single genes rarely have large effects, more often than not playing a role in a host of bodily functions. The relatively simple physical trait of height, for example, is known to be associated with 54 alleles (DNA codings), which collectively account for only 5 percent of heritability—the rest’s a mystery. And, of course, mental traits like depression and empathy are enormously more complicated. As the philosopher Patricia Churchland shows nicely in her book Braintrust: What Neuroscience Tells Us About Morality (Princeton University Press, 2011), the molecule serotonin, for instance, figures in cardiovascular regulation, respiration, circadian rhythm, sleep-wake cycles, appetite, aggression, sexual behavior, sensorimotor reactivity, pain sensitivity, and reward learning. And oxytocin, after a point, suddenly triggers the weakening of mate attachment in female prairie voles rather than the reverse. Drug developers know that the notion of linking a particular gene or gene product to a particular phenotype is at best naïve and usually plain wrong. Neuroscience deserves our public funds, to be certain, but there is much work yet to do.

What if generosity and altruism are ACTUALLY selfish acts of hoarding good feelings for oneself?

According to five measures of well-being tabulated in a nationwide study, the Science of Generosity Initiative, misers are indeed miserable and the generous are happier, as long as giving is a basic part of their lives; onetime donations of blood and even organs fail to spark the feel-good magic.