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The functional adaptations of mammalian brain structures through a behavioural ecology lens

Nature Reviews Biodiversity volume 1, pages 703–716 (2025)Cite this article

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Abstract

The organization of the extant mammalian brain is influenced by development, evolutionary history and the environment. Ecological adaptations specifically have had a major role in shaping the structures and associated functions of the mammalian brain. Although general organization of the brain is relatively conserved in modern mammals, throughout millions of years of evolution mammals have acquired diverse sensory and nervous system adaptations as they invaded new ecological niches. Here, we synthesize palaeontological and neurobiological evidence on mammalian brain structure evolution, the mechanisms behind the observed variation in the size and organization of brain structures, and the effect of behavioural ecology on the evolution of brain functions and associated structures. Neuroecology has advanced greatly over the past 40 years and is now unravelling the complex relationship between specific behaviours and brain organization and function. Relying on different types of data, comparative neurobiologists and palaeontologists strive to answer similar questions about brain evolution, benefiting from a synergistic approach. We conclude this Review by outlining outstanding questions regarding the relationships between structure, function, behaviour and evolution that deserve future research attention, and propose methodologies and approaches to help to resolve these problems.

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Fig. 1: The evolution of mammalian brain structure.
Fig. 2: Organization of the mammalian brain.
Fig. 3: Brain structure size trends.
Fig. 4: Cortical architecture trends in squirrels.

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Acknowledgements

O.C.B. is supported by the Beatriu de Pinós Programme, funded by the Direcció General de Recerca de la Generalitat de Catalunya and managed by AGAUR, expedient number 2021 BP 00042 to O.C.B. O.C.B. is also supported by the Generalitat de Catalunya/CERCA Programme, the Agència de Gestió d’Ajust Universitaris i de Recerca of the Generalitat de Catalunya (2021 SGR 00620) to David M. Alba (Institute Català De Paleontologia). L.K. is supported by NEI (R01EY034303) and NINDS (R01NS115881).

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Authors and Affiliations

  1. Institut Català de Paleontologia Miquel Crusafont (ICP-CERCA), Universitat Autònoma de Barcelona, Barcelona, Spain

    Ornella C. Bertrand

  2. Section of Mammals, Carnegie Museum of Natural History, Pittsburgh, PA, USA

    Ornella C. Bertrand

  3. Center for Neuroscience, University of California, Davis, CA, USA

    Leah Krubitzer

  4. Department of Psychology, University of California, Davis, CA, USA

    Leah Krubitzer

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Glossary

Amniote

Group of tetrapod vertebrates that has evolved an amnion, a closed sac filled with amniotic fluid that surrounds the embryo, allowing its development outside of water.

Bauplan

General structure of the body or region of the body plan that characterizes a group of organisms such as the brain of Mammalia.

Crown clade

Monophyletic group of species that share a common set of morphological features. It includes all the living representatives of a given group, their common ancestor and all its descendants.

Dichromat

Defines organisms that can only distinguish two primary colours. The condition present in most mammals.

Gyrus

Ridge between sulci of the brain. When taken together, they form a system of complex folding pattern. Brains with folding are known as gyrencephalic brains.

Lissencephalic

Characterizes brains that do not present any sulci on their surface.

Sauropsids

Group of amniotes that includes the crown clades birds, crocodiles, turtles and lepidosaurians (tuataras, lizards, snakes and amphisbaenians) and their closest extinct relatives, including non-avian dinosaurs.

Stem taxa

Paraphyletic group of species that lack some characteristics found in the crown clade. For example, stem mammals are considered the closest relatives to the clade Mammalia.

Sulci

Grooves on the surface of the brain. Complex sulci pattern emerges as brain size increases.

Synapsids

Group of amniotes that includes the crown clade Mammalia and their closest extinct relatives, including the pelycosaur Dimetrodon.

Trichromat

Defines organisms that can distinguish all three primary colours. This is the most widespread condition in humans.

Umwelt

Represents the unique way in which organisms perceive the world. This perception will be shaped by the kind of information that can be processed by their sensory organs.

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Bertrand, O.C., Krubitzer, L. The functional adaptations of mammalian brain structures through a behavioural ecology lens. Nat. Rev. Biodivers. 1, 703–716 (2025). https://doi.org/10.1038/s44358-025-00095-0

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