The evolution of mammalian brain size

Smaers, JB; Rothman, RS; Hudson, DR; Balanoff, AM; Beatty, B; Dechmann, DKN; de Vries, D; Dunn, JC; Fleagle, JG; Gilbert, CC; Goswami, A; Iwaniuk, AN; Jungers, WL; Kerney, M; Ksepka, DT; Manger, PR; Mongle, CS; Rohlf, FJ; Smith, NA; Soligo, C; Weisbecker, V; Safi, K

Abstract

Relative brain size has long been considered a reflection of cognitive capacities and has played a fundamental role in developing core theories in the life sciences. Yet, the notion that relative brain size validly represents selection on brain size relies on the untested assumptions that brain-body allometry is restrained to a stable scaling relationship across species and that any deviation from this slope is due to selection on brain size. Using the largest fossil and extant dataset yet assembled, we find that shifts in allometric slope underpin major transitions in mammalian evolution and are often primarily characterized by marked changes in body size. Our results reveal that the largest-brained mammals achieved large relative brain sizes by highly divergent paths. These findings prompt a reevaluation of the traditional paradigm of relative brain size and open new opportunities to improve our understanding of the genetic and developmental mechanisms that influence brain size.

Citation

Smaers, J., Rothman, R., Hudson, D., Balanoff, A., Beatty, B., Dechmann, D., …Safi, K. (2021). The evolution of mammalian brain size. Science Advances, 7(18), eabe2101. https://doi.org/10.1126/sciadv.abe2101

• Journal Article Type: Article
• Acceptance Date: Mar 10, 2021
• Publication Date: Apr 28, 2021
• Deposit Date: May 7, 2021
• Publicly Available Date: May 7, 2021
• Journal: Science Advances
• Publisher: American Association for the Advancement of Science
• Volume: 7
• Issue: 18
• Pages: eabe2101
• DOI: https://doi.org/10.1126/sciadv.abe2101
• Publisher URL: https://doi.org/10.1126/sciadv.abe2101
• Related Public URLs: http://advances.sciencemag.org/
• Additional Information: Additional Information : ** Article version: VoR ** From Crossref journal articles via Jisc Publications Router ** Licence for VoR version of this article starting on 28-04-2021: https://creativecommons.org/licenses/by-nc/4.0/ **Journal IDs: eissn 2375-2548 **History: published_online 28-04-2021; Funders : National Science Foundation;H2020 European Research Council;Gerstner Fellowship and the Gerstner Family Foundation, the Kalbfleisch Fellowship, and the Richard Gilder Graduate School of the American Museum of Natural History;Australian Research Council;Natural Environment Research Council (NERC);Gerstner Family Foundation; Projects : "Rise of the continent of the monkeys": an integrated genomic and fossil-based analysis of the adaptive radiation of New World primates;80692;ERC-Stg-637171;unspecified;DP170103227; Grant Number: 80692; Grant Number: ERC-Stg-637171; Grant Number: DP170103227; Grant Number: NE/T000341/1