But each skull rather than each group was given equal weight. Using Morton's data and weighting subgroups equally, the Indian average becomes 83.79. Now Caucasians drop from 87 to 84.45. Pretty much the same as the Indian value. Anyway, ignoring that, and looking at those skulls which came from mummies, so that race and sex could be ascertained with certainty, another little error emerges.
Men tend to be bigger than women, and so have bigger heads.
Although Morton recorded sex data, he never separated his skulls by sex, perhaps because he happened to have more black females than males, and more white males than females. Anyway, he published his standard rankings, but after correction, his data show only sex differences in size, not race differences. Here's my personal favorite of Morton's errors. After Morton switched to BBs from mustard seed, his estimate of the black average went from 78 to 85. Seed had required some degree of packing.