There is no fundamental difference between humans and the higher mammalsin their mental faculties

The chief distinction in the intellectual powers of the two sexes is shown by mans attaining to a higher eminence, in whatever he takes up, than the woman. Whether deep thought, reason, or imagination or merely the use of the senses and hands.....We may also infer.....The average mental power in man must be above that of woman.

...for the shield may be as important for victory, as the sword or spear.

And hail their queen, fair regent of the night.

The lower animals, on the other hand, must have their bodily structure modified in order to survive under greatly changed conditions. They must be rendered stronger, or acquire more effective teeth or claws, in order to defend themselves from new enemies; or they must be reduced in size so as to escape detection and danger. When they migrate into a colder climate they must become clothed with thicker fur, or have their constitutions altered. If they fail to be thus modified, they will cease to exist.

The western nations of Europe, who now so immeasurably surpass their former savage progenitors, and stand at the summit of civilization, owe little or none of their superiority to direct inheritance from the old Greeks, though they owe much to the written works of that wonderful people.

I am actually weary of telling people that I do not pretend to adduce [direct] evidence of one species changing into another, but I believe that this view is in the main correct, because so many phenomena can thus be grouped end explained.