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Updated: Jan 26, 2026
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In Situ Visualization of Axon Growth and Growth Cone Dynamics in Acute Ex Vivo Embryonic Brain Slice Cultures
Published on: October 14, 2021
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Brain size growth in Australopithecus.
1Anthropology Department, Vassar College, 124 Raymond Avenue, Box 42, Poughkeepsie, NY 12603, USA.
Journal of Human Evolution
|April 24, 2019
Summary
Early hominin brain growth rates were slower than previously thought. Australopithecus afarensis and Australopithecus africanus showed lower postnatal brain growth compared to modern humans, indicating complex evolutionary patterns.
Area of Science:
- Paleoanthropology
- Evolutionary Biology
- Neuroscience
Background:
- Human brain size evolution is linked to extended postnatal growth periods.
- Assessing early hominin brain growth is challenging due to limited fossil evidence.
Purpose of the Study:
- To reconstruct and compare postnatal brain growth rates in Australopithecus afarensis and Australopithecus africanus.
- To investigate the timing of accelerated brain growth in human evolution.
Main Methods:
- Utilized Monte Carlo simulations to estimate brain growth rates.
- Reconstructed neonatal brain size using catarrhine scaling relationships.
- Analyzed fossil infant specimens (A.L. 333-105, DIK-1-1, Taung) for age and brain size.
Main Results:
- Australopithecus afarensis exhibited significantly lower average annual rates (ARs) and proportional size change from birth (PSC) than chimpanzees and gorillas.
- Australopithecus africanus showed ARs and PSCs comparable to chimpanzees and gorillas.
- These findings suggest high rates of brain growth emerged later in human evolution.
Conclusions:
- Early hominins possessed distinct brain anatomy but not accelerated postnatal brain growth.
- Brain growth rates are not solely determined by adult brain size.
- This study offers insights into the evolution of hominin brain development despite fossil record limitations.
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