The present descendants of those races which are pictured in early Egyptian tombs show no perceptible change in their bodily appearance, and there is no reason to believe that the mental faculties and tendencies with which they are born have changed to any greater degree.
The numerical proportions of different races in the world have, indeed, altered during that period, as one race proved weaker in war or less able to resist disease than another; and races have been mingled by marriage following upon conquest.

But if a baby could now be exchanged at birth with one born of the same breeding-stock even a hundred thousand years ago, one may suppose that neither the ancient nor the modern mother would notice any startling difference.

The child from the Stone Age would perhaps suffer more seriously than our children if he caught measles, or might show somewhat keener instincts in quarrelling and hunting, or as he grew up be rather more conscious than his fellows of the 'will to live' and 'the joy of life.' Conversely, a transplanted twentieth-century child would resist infectious disease better than the other children in the Stone Age, and might, as he grew up, be found to have a rather exceptionally colourless and adaptable character.

But there apparently the difference would end.

In essentials the type of each human stock may be supposed to have remained unchanged throughout the whole period.