Come on guys let's applaud him for making an effort.
While your example is simplistic, you have the gist of it. At it's essence, it is "survival of the fittest". If you have an advantage, you are more likely to survive and pass on that advantage to your children.
It's interesting to note that it is often the weaker members of a species that must adapt or die. The strong can continue on eating whatever food source they are used to, but the weak get forced out and have to find an alternative. This is likely the reason that humans walk upright. As the lush jungles of the Great Valley Rift
began to dry up, and the trees started growing farther and farther apart, the weaker apes
were forced to search farther and farther to gather food, and adapted to upright posture and running. The stronger apes didn't have to change.
But eventually as the Rift turned to desert, the upright runner apes could go find a new habitat, but the stronger apes who forced them away eventually died out. Humans are not as strong as many animals, or as fast. Our eyes, noses, and ears are not as keen. Our teeth and claws can't compare to most other species. It's because of these disadvantages that our brains have become so developed.
One could ask, well why didn't we evolve to be stronger or faster or have sharp teeth and long claws instead? We did. All living things on earth share a common ancestor. We are related to bears and snakes and eagles too. Just not as closely or recently as apes.
It amuses me that theists deny evolution yet they still look for an attractive, healthy mate to produce attractive, healthy children.