Image of the Day: Slow-Growing Brains
Image of the Day: Slow-Growing Brains

Image of the Day: Slow-Growing Brains

Scans of eight fossilized adult and infant Australopithecus afarensis skulls reveal a prolonged period of brain growth during development that may have set the stage for extended childhood learning in later hominins.

Amy Schleunes
Amy Schleunes
Apr 8, 2020

ABOVE: The A. afarensis “Dikika child” fossilized skull from Ethiopia. “The colors represent the different fragments of the bone that were defined based on computed tomographic scans of the original bones,” coauthor Philipp Gunz tells The Scientist in an email. “Subsequently, I repositioned these fragments on the computer so as to correct for damage [to] the bone after death.”
PHILIPP GUNZ, MPI EVA LEIPZIG

The brains of Australopithecus afarensis, a hominin species that lived in eastern Africa more than 3 million years ago, were organized in a manner similar to those of apes, report the authors of a study published on April 1 in Science Advances, but they also indicate a slow growth period like that found in modern humans.

“The fact that protracted brain growth emerged in hominins as early as 3.3 Ma ago could suggest that it characterized all of subsequent hominin evolutionary history,” the authors write in the paper, though brain development patterns in hominins may not have followed a linear trajectory in the evolutionary process that led to modern humans. Whatever the evolutionary pattern, they say, the extended brain growth period in A. afarensis “provided a basis for subsequent evolution of the brain and social behavior in hominins and was likely critical for the evolution of a long period of childhood learning.”

Virtually arranged bone fragments of the A. afarensis “Dikika child” skull
PHILIPP GUNZ, MPI EVA LEIPZIG

P. Gunz et al., “Australopithecus afarensis endocasts suggest ape-like brain organization and prolonged brain growth,” Science Advances, doi:10.1126/sciadv.aaz4729, 2020.