Truth in science can be defined as the working hypothesis best suited to open the way to the next better one.

Historians will have to face the fact that natural selection determined the evolution of cultures in the same manner as it did that of species.

It is a good morning exercise for a research scientist to discard a pet hypothesis every day before breakfast. It keeps him young.

Man appears to be the missing link between anthropoid apes and human beings.

I believe that present day civilized man suffers from insufficient discharge of his aggressive drive

Hatred of humanity and love of animals make a very bad combination.

The bond with a dog is as lasting as the ties of this earth can ever be.