What is the primary factor driving natural selection?

The primary factor driving natural selection is the physical characteristics that influence the chances of survival and reproduction of individuals in a population. This concept, foundational to the theory of evolution, emphasizes that certain traits beneficial for survival in a specific environment allow individuals to be more successful in reproducing and passing on those advantageous traits to their offspring.

Over generations, this leads to a change in the population, where the traits that enhance survival become more common. This process is often summarized by the phrase "survival of the fittest," where "fittest" refers to those best adapted to their environment, rather than being the strongest or the fastest.

While random changes in the environment, increased genetic variation, and inter-species relationships can influence the context in which natural selection occurs, they are not the primary driving factors of the selection itself. Instead, it is the interaction of those physical traits with the environment that determines which individuals thrive and which do not.