### For over a century, a debate has raged in the heart of evolutionary science. Is natural selection limited to selfish action by genes, or can altruism within groups of genes or organisms improve fitness? The distinction can seem slight, but it raises important questions.

## Does altruism exist?

### The debate exists at two levels: ideas about how genes contribute to the success of organisms, and the mathematics describing that process. The ideas are embodied in scenarios that we can think about; the mathematics is used to prove that we understand something completely general. However, the scenarios have assumptions that may be put into the math, and the proofs depend on those assumptions. We have shown that underlying the debate is an over reliance on statistics that misses relevant variables—variables that need to be included to understand what is happening. Even when equations are solved correctly, if the right variables are not included, the conclusions are not necessarily correct. Translating this back into the ideas is a key step that can help us understand what can happen with altruism. In these pages we will explain the ideas and why they are not included in the way evolution is taught in both popular books and textbooks.

Yaneer Bar-Yam, **Brief discussion of the mathematics of kin and group selection**, New England Complex Systems Institute (January 22, 2019).