Selfish behavior is alarmingly prevalent in biological contexts. A recent study underscores this, illustrating how genetic mutations accumulate in the sperm of older men. Research indicates that as men age, new stem cells increase the likelihood of carrying disease-related mutations, potentially affecting up to 5% of their sperm by the time they reach 70.

This discovery highlights not only the advantages of having children at a younger age but also the indifferent nature of mutated stem cells, which do not consider the consequences for future offspring as long as their genetic material is passed on. This serves as a potent reminder that the notion of “selfish genes” remains a foundational concept in evolutionary biology. Genes prioritize their own survival over any altruistic intentions, continually bringing discussions back to genetic selection, contrary to the idea of “survival of the fittest.”

The ongoing debate is weary and centers around whether evolution through natural selection favors cooperation or promotes competitive and ruthless organisms that prioritize reproduction above all else. Over the past century, numerous biologists have debated this issue, labeling differing perspectives on group versus individual selection. These distinctions fundamentally shape our understanding of the natural world and our role within it.

The divide between these views has consistently straddled ideological lines. Earlier animal behaviorists believed that organisms act for the benefit of their species. The idea was that individual survival is advantageous for the entire group, creating a potential contributor to the continuation of humanity. Homo sapiens can achieve this common goal through mutual assistance.

However, as highlighted by key biologists from Ronald Fisher to contemporary thinkers like Richard Dawkins, organisms that accept help from others without reciprocating consistently outperform those that give help. Those that disrupt group dynamics tend to position themselves for greater success—as long as their impact isn’t so destructive that it eliminates all competition.

From an evolutionary standpoint, the optimal strategy for individuals is to encourage cooperation while withholding it from others—ideally, without detection. Instead of fostering good and altruistic qualities, cooperation can create an environment where competitive and exploitative behaviors thrive unnoticed.

The issue of destruction undermines populations, whether they are gametes, bacteria, animals, or humans. Stem cells, which reproduce at the expense of a host’s descendants, are indifferent to whether their proliferation harms future generations. The welfare of both the host and its species is irrelevant.

This logic extends to human societies, both ancient and modern. Individuals in power—often older men—tend to monopolize resources and frequently choose younger women as partners. Given the adverse effects of older men on fertility, it’s challenging to take the group selection model seriously in light of new findings regarding sperm.

Crucially, these unsettling realities about our biological roots do not dictate our behavior today. We should strive for mutual aid and not take it for granted. Recognizing our inherent selfish tendencies at every biological level is the initial step toward overcoming them.

Jonathan R. Goodman is the author of Invisible Rivals: How We Evolved to Compete in a Cooperative World