I compared data from an old and new study of brain size. The old data was analyzed by FW and EM Appel who wrote in 1942:

The material came from the St. Elizabeth’s Hospital of Washington, D. C. Dr. Walter Freeman, who was formerly pathologist at this hospital, brought certain biometrie data from the autopsy records of the Hospital to the Department of Biology of the Johns Hopkins School of Hygiene and Public Health for statistical analysis. Beginning with

the first autopsy after the founding of the Hospital, the records date from 1884. The records available for the present work run consecutively through 1924, and then skip to a few for 1933. The cases for the interval between 1924 and 1933 were used by Freeman in his studies on the endocrine organs (Freeman, 1931, 1934; Pearl, Gooch, and Freeman, 1935 )• For the remaining body of material, totaling nearly 4500 data sheets, 2752 records have been segregated. These include all of the male, white cases for which the weight of the brain is given. This array of cases is much more extensive than any series for one sex and one race which has been available heretofore from a single source.

This was then compared with more recent U.S. data from a 1980 study from Ho et al.

The mean age for both the whites and blacks in Ho’s study was about 60 so it’s possible to compare the average of Ho’s circa 1980 white males with the 55 to 64 year-old white males from 1884 to 1933. And because Ho et al, used regression to estimate brain size at age 25, we can also compare circa 1980 white men age 25 to the 25-29 year-old while men from 1884 to 1933.

Here are the comparisons:

Of course it’s possible the brains were not weighed using the same procedure causing such a large increase to be spurious. However Richard Lynn has been arguing for decades that thanks to 20th century nutrition and health, a major brain size increase has occurred, and is consistent with major intelligence increase. This makes sense because the last few hundred years have been a quantum leap forward in human achievement. It took 70,000 years for our population to increase to 1 billion people, yet technology has allowed us to reach 7 billion in just the last few centuries, not to mention space travel, the internet, and genetic engineering.