Passage A

 Evolutionary psychology has taught us to examine human behavior from the standpoint of the theory of evolution—to explain a given type of human behavior by examining how it contributes to the reproductive success of individuals exhibiting the behavior, and thereby to the proliferation of the genetic material responsible for causing that behavior. From an evolutionary standpoint, the problem of altruism is a thorny one: what accounts for the evolution of behavior in which an individual expends energy or other valuable resources promoting the welfare of another individual?

The answer probably lies in the psychological experiences of identification and empathy. Such experiences could have initially arisen in response to cues (like physical resemblance) that indicated the presence of shared genetic material in human ancestors. The psychological states provoked by these cues could have increased the chances of related individuals' receiving assistance, thereby enhancing the survival and replication of genes influencing the capacity for identification and empathy. This would account, for example, for a mother's rushing to help her injured child; genes promoting their own self-propagation may thus operate through instinctive actions that appear unselfish.

Since human ancestors lived in small, kin-based groups, the application of altruistic mechanisms to the entire group would have promoted the propagation of the genes responsible for those mechanisms. Later, these mechanisms may have come to apply to humans who are not kin when communities grew larger. In this way, apparently altruistic mechanisms may have arisen within a genetically "selfish" system.

Passage B

Evolutionary psychology is a kind of conspiracy theory; that is, it explains behavior by imputing an interest (the proliferation of genes) that the agent of the behavior does not openly acknowledge, or indeed, is not even aware of. Thus, what seemed to be your unsurprising interest in your child's well-being turns out to be your genes' conspiracy to propagate themselves.

Such arguments can appear persuasive on the face of it. According to some evolutionary psychologists, an interest in the proliferation of genes explains monogamous families in animals whose offspring mature slowly. Human offspring mature slowly; and, at least in numerical terms, our species favors monogamous families. Evolutionary psychologists take this as evidence that humans form monogamous families because of our interest in propagating our genes. Are they right?

Maybe yes, maybe no; this kind of inference needs to be handled with great care. There are, most often, all sorts of interests that would explain any given behavior. What is needed to make it decisive that a particular interest explains a particular behavior is that the behavior would be reasonable only if one had that interest. But such cases are vanishingly rare: an interest in Y might explain doing X, but so too would an interest in doing X. A concern to propagate one's genes would explain promoting the welfare of one's children; but so too would an interest in the welfare of one's children. Not all of one's motives can be instrumental, after all; there must be some things that one cares for just for their own sakes.