Why is it impossible to understand biology in the absence of evolution?
Evolution is necessary to the understanding of biology because biological species are the products of evolution; without evolution, they (and we) wouldn’t exist. Evolution explains the similarities between related species, the progression of past species as preserved in the fossil record, and the existence of vestigial organs (for example, some snakes have the remnants of hind limbs, a legacy from their four-legged reptilian ancestors).