Progress has been much more general than retrogression

It is not the biggest, the brightest or the best that will survive, but those who adapt the quickest.

There is no fundamental difference between man and the higher mammals in their mental faculties...The difference in mind between man and the higher animals, great as it is, certainly is one of degree and not of kind.

Intelligence is based on how efficient a species became at doing the things they need to survive.

Not one change of species into another is on record ... we cannot prove that a single species has been changed.

I have been speculating last night what makes a man a discoverer of undiscovered things. As far as I can conjecture the art consists in habitually searching for the causes and meaning of everything which occurs.

Nothing exists for itself alone, but only in relation to other forms of life