Imagine a world where only the strongest, smartest, and most adaptable creatures survive. This is the essence of natural selection, often summarized as "survival of the fittest." It's a principle that has shaped the evolution of life on Earth for billions of years, determining which species thrive and which fade into extinction. From the majestic lions of the African savannah to the resilient bacteria in your gut, natural selection influences every living organism's chance at survival and reproduction.