title: No relative expansion of the number of prefrontal neurons in primate and human evolution.
abstract: Human evolution is widely thought to have involved a particular expansion of prefrontal cortex. This popular notion has recently been challenged, although controversies remain. Here we show that the prefrontal region of both human and nonhuman primates holds about 8% of cortical neurons, with no clear difference across humans and other primates in the distribution of cortical neurons or white matter cells along the anteroposterior axis. Further, we find that the volumes of human prefrontal gray and white matter match the expected volumes for the number of neurons in the gray matter and for the number of other cells in the white matter compared with other primate species. These results indicate that prefrontal cortical expansion in human evolution happened along the same allometric trajectory as for other primate species, without modification of the distribution of neurons across its surface or of the volume of the underlying white matter. We thus propose that the most distinctive feature of the human prefrontal cortex is its absolute number of neurons, not its relative volume.
authors: Instituto de Ciências Morfológicas, Universidade Federal do Rio De Janeiro, 21941-901, Rio de Janeiro, Brazil; Instituto Nacional de Neurociência Translacional, 04023-900, Sao Paulo, Brazil; Department of Psychology, Vanderbilt University, Nashville, TN 37240;
authors: Mariana
authors: M
authors: Gabi
authors: Instituto de Ciências Morfológicas, Universidade Federal do Rio De Janeiro, 21941-901, Rio de Janeiro, Brazil; Instituto Nacional de Neurociência Translacional, 04023-900, Sao Paulo, Brazil;
authors: Kleber
authors: K
authors: Neves
authors: Instituto de Ciências Morfológicas, Universidade Federal do Rio De Janeiro, 21941-901, Rio de Janeiro, Brazil; Instituto Nacional de Neurociência Translacional, 04023-900, Sao Paulo, Brazil;
authors: Carolinne
authors: C
authors: Masseron
authors: Instituto de Ciências Morfológicas, Universidade Federal do Rio De Janeiro, 21941-901, Rio de Janeiro, Brazil; Instituto Nacional de Neurociência Translacional, 04023-900, Sao Paulo, Brazil;
authors: Pedro F M
authors: PF
authors: Ribeiro
authors: Instituto de Ciências Morfológicas, Universidade Federal do Rio De Janeiro, 21941-901, Rio de Janeiro, Brazil; Instituto Nacional de Neurociência Translacional, 04023-900, Sao Paulo, Brazil;
authors: Lissa
authors: L
authors: Ventura-Antunes
authors: Universidade Federal de São Paulo, 04021-001, Sao Paulo, Brazil; Museu Paraense Emílio Goeldi, 66040-170, Belem, Brazil;
authors: Laila
authors: L
authors: Torres
authors: Instituto de Física, Universidade Federal do Rio De Janeiro, 21941-901, Rio de Janeiro, Brazil;
authors: Bruno
authors: B
authors: Mota
authors: Department of Psychology, Vanderbilt University, Nashville, TN 37240; jon.h.kaas@vanderbilt.edu suzana.herculano@vanderbilt.edu.
authors: Jon H
authors: JH
authors: Kaas
authors: Instituto de Ciências Morfológicas, Universidade Federal do Rio De Janeiro, 21941-901, Rio de Janeiro, Brazil; Instituto Nacional de Neurociência Translacional, 04023-900, Sao Paulo, Brazil; Department of Psychology, Vanderbilt University, Nashville, TN 37240; Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235 jon.h.kaas@vanderbilt.edu suzana.herculano@vanderbilt.edu.
authors: Suzana
authors: S
authors: Herculano-Houzel
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002452:Cell Count; D005260:Female; D066128:Gray Matter / Q000033:anatomy & histology / Q000166:cytology* / Q000502:physiology; D006801:Humans; D008297:Male; D008867:Microtomy; D009474:Neurons / Q000166:cytology* / Q000502:physiology; D017397:Prefrontal Cortex / Q000033:anatomy & histology / Q000166:cytology* / Q000502:physiology; D011323:Primates; D013045:Species Specificity; D066127:White Matter / Q000033:anatomy & histology / Q000166:cytology* / Q000502:physiology
keywords: cortical expansion; evolution; number of neurons; prefrontal cortex; primate