differences which have been made since Francis Galton led the way, I do not find one that lends any support to the doctrine of human initial
equality, total or approximate. On the contrary, every one of them gives evidence that if the thousand babies born this week in New York City were given equal opportunity they would still differ in much the same way and to much the same extent as they will in fact differ.
We find, for instance, that the children of certain families rank very much higher in certain psychological tests of perception, association and the like, than the children of certain other families. Now if this difference were due to the difference between the two groups of families in environment—in ideals, customs, hygienic conditions and the like—it should increase greatly with the age of the children in some rough proportion to the length of time that they are subject to the beneficent or unfavorable environment. It does not. One family's product differs from another nearly as much at the age of 9 to 11 as at the age of 12 to 14.
Again, if inequalities in the environment produce the greater part of these differences, equalizing opportunity and training should greatly reduce them. Such equalization is found by experiment to reduce them very little, if at all. Chart 4 shows, for example, the result of equal amounts of training applied to two groups of adults whom life in general had previously brought to the conditions shown at the left of the chart. The trait chosen was addition; from life in general one group had gained the ability to do twenty-seven more additions per minute than the other group, accuracy being equal in the two groups. At the end of the special training the superior individuals had gained on the average 28 additions per minute, while the inferior individuals gained
