When we scientists say two species are more closely related, another way of saying it is they share a

common ancestor.

This means that at some point in the past, these two species diverged from a common ancestor and have since evolved into separate species with unique characteristics. The closer the relationship between two species, the more recently they shared a common ancestor and the more similar their genetic makeup is likely to be. This concept of common ancestry is a fundamental principle in evolutionary biology and helps us understand the relationships between different organisms on Earth.