God has planted in life an ability to adjust itself to changed conditions and environment, within limits. The Bible does not guarantee fixity of type such as the length of a bone or the color of a feather. It does guarantee a fixity of what it calls "kind" so that nature can never turn a turkey into a goose. Move a polecat to a cold climate and it will grow heavier fur and not take a geological age to do it. Move it to a rainy climate and it will not grow an umbrella in any period of time. Nature may modify what the creature has, but cannot create an organ that it has not. The boy who persists in smoking will find his body speedily adjusts itself to nicotine, so that nausea ceases, and it does not take glaciers, sinking continents and earthquakes to do it; but he will not grow a pipe or a smokestack while the world standeth.

One eminent writer explains that deer developed antlers because for ages, the males pushed their heads together and made callous places that finally turned into horns.
 

If pressure will produce horns, why have they not developed on man's feet?

Why does the deer shed his antlers?

Why should he have more spikes on his antlers each year?

Why should horns grow in forks with one animal and spirals with another?

Isn't it about time for work horses to get the beginnings of horns on their shoulders.

If bruises produce horns, the turtle and porcupine must have had some activity like football.

Some exponents of the doctrine have abandoned this theory. In fact, there is no phase of evolution that someone has not abandoned.

Not only are creatures unable to develop what they have not got, but what they haven't got does not need to be developed. If a creature can get along without a marsupial pouch to carry its babies in (AND THEY DO), what is the distressing need that will evolve one? Whatever handicap the creatures have, they hold their own. The slow going toad catches insects enough, and that is all a swallow can do. Not being able to go South, the toad doesn't need to. The bat with its wings, has not crowded out the mouse that must go afoot.