Final answer:
The concept of uniformitarianism asserts that the same geological processes we observe today have been shaping Earth for much longer than previously thought, providing a framework for Charles Darwin's theory of natural selection, which explains the diversity of life through evolutionary change.
Step-by-step explanation:
The thought that past geological events are the product of the same environmental forces that are at work today is a key principle known as uniformitarianism. This concept is closely related to the development of the theory of natural selection. Charles Lyell, often referred to as the father of modern geology, made significant contributions to evolutionary thinking with his Principles of Geology. He posited that if Earth's geological features could be formed by slow, gradual processes that are still occurring, then it would mean Earth was substantially older than the few thousand years previously thought. This realization extended the timescale for evolutionary processes and allowed for the gradual change observed in species, providing a geological timescale that supported Darwin's observations and hypotheses on evolution.
Darwin, influenced by Lyell and others, understood that just as selective breeding could rapidly produce desirable traits in organisms, natural forces could also select for traits over longer periods, leading to the diversity of life we see today. This supported his theory of evolution by natural selection, where those with favorable traits reproduce more and thus affect the genetic makeup of future generations. Both Wallace and Darwin saw that natural selection could lead to evolutionary change as 'survival of the fittest' came into play with individuals better suited to their environment.