The evolution of brains from early mammals to humans.
Level 5 - mechanism / opinion, no new human data
Level 5 by design analogy (narrative evolutionary review synthesizing comparative anatomy and fossil records without systematic review methodology)
PubMed 23529256 · doi:10.1002/wcs.1206
What was done
This narrative review synthesized findings from comparative neuroanatomy of extant mammals and vertebrates, fossil endocast records, developmental biology, and cortical scaling principles to describe the anatomical evolution of the brain from early mammals to humans.
What was found
The review outlines major evolutionary steps: early mammals transformed ancestral single-layered dorsal cortex into a six-layered neocortex comprising 20 to 25 cortical areas; early primates evolved expanded visual, posterior parietal, and prefrontal areas adapted for arboreal niches; and following divergence from chimpanzee ancestors 6 to 8 million years ago (who had brains approximately one-third human size), brain volume markedly expanded over the last 2 million years, especially in prefrontal, posterior parietal, lateral temporal, and insular regions. The abstract reports qualitative anatomical trajectories and historical timelines without quantitative statistical metrics.
Why it matters
It outlines an anatomical and evolutionary framework linking comparative primate neurobiology and paleontology to the expansion of human cognitive and cortical networks.
Limits
As a narrative review, it lacks a systematic search methodology, meta-analytic data, and sample sizes. Reconstructions of ancestral brain architecture rely heavily on fossil cranial endocasts and comparisons among surviving modern species rather than direct observation of soft tissue in extinct ancestors.
Cited by
- supports Humans have more distinct sensory cortical areas than monkeys and more distant mammalian relatives.