Quantitative uniqueness of human brain evolution revealed through phylogenetic comparative analysis

  1. Ian Forrester Miller  Is a corresponding author
  2. Robert A Barton
  3. Charles L Nunn
  1. Princeton University, United States
  2. University of Durham, United Kingdom
  3. Duke University, United States


While the human brain is clearly large relative to body size, less is known about the timing of brain and brain component expansion within primates and the relative magnitude of volumetric increases. Using Bayesian phylogenetic comparative methods and data for both extant and fossil species, we identified that a distinct shift in brain-body scaling occurred as hominins diverged from other primates, and again as humans and Neanderthals diverged from other hominins. Within hominins, we detected a pattern of directional and accelerating evolution towards larger brains, consistent with a positive feedback process in the evolution of the human brain. Contrary to widespread assumptions, we found that the human neocortex is not exceptionally large relative to other brain structures. Instead, our analyses revealed a single increase in relative neocortex volume at the origin of haplorrhines, and an increase in relative cerebellar volume in apes.

Data availability

All data used in our analyses are provided as supplementary material.

Article and author information

Author details

  1. Ian Forrester Miller

    Ecology and Evolutionary Biology, Princeton University, Princeton, United States
    For correspondence
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-2673-9618
  2. Robert A Barton

    Department of Anthropology, University of Durham, Durham, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  3. Charles L Nunn

    Department of Evolutionary Anthropology, Duke University, Durham, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-9330-2873


National Science Foundation (BCS-1355902)

  • Charles L Nunn

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Jessica C. Thompson, YALE, United States

Publication history

  1. Received: August 22, 2018
  2. Accepted: January 29, 2019
  3. Accepted Manuscript published: January 31, 2019 (version 1)
  4. Version of Record published: February 18, 2019 (version 2)


© 2019, Miller et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.


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  1. Ian Forrester Miller
  2. Robert A Barton
  3. Charles L Nunn
Quantitative uniqueness of human brain evolution revealed through phylogenetic comparative analysis
eLife 8:e41250.

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