Brain growth in modern humans using multiple developmental databases.

Objective Currently, there are several published articles detailing brain growth in modern humans. The contained databases were derived using disparate methodologies. The objective of the present investigation was to determine the level of agreement among several collections of immature modern human brains. Materials and methods Twenty-one developmental collections of endocranial volume, brain weight, or brain volume were selected for analysis, including one skeletal, six autopsy, and 14 computed tomography/magnetic resonance imaging samples. Step-wise comparisons were determined, using conversion factors for brain specific gravity and size of the subarachnoid space. Results Derived brain weights are comparable and increase especially during the first year of postnatal life, with a further slight increase (+8-10%) between one and five years, and little change thereafter. The expansion in brain size occurs earlier than body size. Significant sex differences are apparent at all stages of development. Combining all datasets produced a composite database consisting of 3,491 brain weight values, with ages near birth through 18 years. Individual brain weights ranged from 190 to 1,792 g, and mean brain weights ranged from 457 to 1,365 g, with an overall mean and standard deviation of 897 +/- 387 g. Conclusions The investigation compares modern human collections regarding brain size trajectories from birth through 18 years of age. The 21 datasets are then incorporated into a single composite database. All major age groups and both sexes are well represented. The composite database should prove useful to other investigators interested in developmental aspects of the modern human brain.