Is altruism learned or innate? In The Altruistic Brain: How We Are Naturally Good (Oxford University Press, 2015; 312 pages), neuroscientist Donald W. Pfaff argues that the human brain is wired for selflessness. To make his case, Pfaff postulates that our development and survival have hinged on the care we receive from loved ones, a relationship that has primed us to help others. Pfaff then proposes the altruistic brain theory, which, he writes, “explains exactly how altruistic behavior happens when it happens.” He lays out a five-step process by which our brain unconsciously drives us to act altruistically. To his credit, Pfaff tries to unravel an immensely complex topic, but the book may fall short for the same reason: his attempt to explain altruism in a single theory leads him to make logical leaps and to oversimplify his case.

Perhaps, in trying to understand altruism, we need to look beyond brain function. In Does Altruism Exist? Culture, Genes, and the Welfare of Others (Yale University Press, 2015; 192 pages), evolutionary biologist David Sloan Wilson explores altruism through an evolutionary lens and makes a compelling case that true examples of altruistic behavior can be found in a number of social animals and, especially, in humans. Wilson argues that natural selection extends beyond traits that are shaped by genes; it also applies to traits influenced by culture. “Unrestrained self-interest is far more likely to undermine the common good,” he writes. Consequently, “altruistic groups beat selfish groups.” Wilson concludes by making a sweeping statement that to benefit, or perhaps save, humanity, people must prioritize their altruistic tendencies. In other words, we should spread the love.

But altruism may not be the key to understanding human virtue. In The Moral Arc: How Science and Reason Lead Humanity toward Truth, Justice, and Freedom (Henry Holt,* 2015; 560 pages), skeptic and Scientific American columnist Michael Shermer proposes that our reliance on scientific and rational thinking is actually what has driven people and society to become more moral. Shermer defines moral progress as an “improvement in the survival and flourishing of sentient beings.” He cites studies tracking the historical decline in war-related deaths and (despite some recent lapses) government-sanctioned torture, progress in our views of human rights with the abolition of slavery, and more. He appears to overstate, however, the degree to which science has inspired this moral progress.

Relying heavily on anecdotes to depict how we have replaced magical thinking with scientific prowess, Shermer fails to fully recognize the role science has played in morally questionable ventures (the atomic bomb, for one). Despite such flaws, his work does offer an intriguing, fresh take on how we have advanced as moral beings.