There is a long-running about whether birds first took off by running and flapping from the ground up, or whether they jumped as gliders from the tree down.
What drives natural selection? Evolutionary forces. What are evolutionary forces? They’re what drive natural selection.
Thinking about all the species of animals, birds, and fishes, it becomes apparent that each one requires a certain type of food, suitable for its anatomy.
Charles Darwin pointed to small changes like finch beak size and peppered moth color as visible evidence of an unguided evolutionary process at work.
Epigenetic mechanisms are ubiquitous in biology. Because of epigenetics, organisms with otherwise identical genes (e.g., twins) can be quite different.