As biologists explore the variation across the genomes of living people, they’ve found evidence of evolution at work. Particular variants of genes increase or decrease in populations through time. Sometimes this happens by chance. Other times these changes in frequency result from the gene’s helping or hindering individuals’ survival.
Most mammals rely on scent rather than sight. Look at a dog’s eyes, for example: they’re usually on the sides of its face, not close together and forward-facing like ours. Having eyes on the side is good for creating a broad field of vision, but bad for depth perception and accurately judging distances in front.