González-Forero Mauricio, Gómez-Robles Aida
Konrad Lorenz Institute for Evolution and Cognition Research, Klosterneuburg A-3400, Austria.
Department of Anthropology, University College London, London WC1H 0BW, UK.
Philos Trans R Soc Lond B Biol Sci. 2025 Jun 26;380(1929):20240114. doi: 10.1098/rstb.2024.0114.
Why the human brain size evolved has been a major evolutionary puzzle since Darwin, but addressing it has been challenging. A key reason is the lack of research tools to infer the causes of a unique event for which experiments are not possible. We suggest that analogous problems have been successfully addressed in other disciplines using what has been recently termed simulation-based inference. Following that approach, we outline a strategy to address why the human brain size evolved: hypotheses are expressed in mechanistic models that yield quantitative predictions for evolutionary and developmental trajectories of brain and body sizes, the predicted trajectories are compared with data, and models are chosen by their ability to explain the data. We discuss a recently published model that makes quantitative predictions for evolutionary and developmental trajectories of brain and body sizes for six hominin species, and compare the model predictions with data, finding that the model recovers many aspects of hominin evolution and development. Counter-intuitively, the human brain size evolves in this model as a spandrel or by-product of selection for something else, namely, fertility-determinant traits. Our analysis indicates that simulation-based inference offers a way forward to infer why the human brain size evolved.This article is part of the Theo Murphy meeting issue 'Selection shapes diverse animal minds'.
自达尔文时代以来，人类大脑为何会进化一直是一个重大的进化谜题，但解决这个问题颇具挑战性。一个关键原因是缺乏研究工具来推断一个无法进行实验的独特事件的成因。我们认为，类似的问题在其他学科中已通过最近被称为基于模拟的推断法成功解决。遵循该方法，我们概述了一种解决人类大脑为何进化的策略：假设以机械模型表达，这些模型对大脑和身体大小的进化及发育轨迹产生定量预测，将预测轨迹与数据进行比较，并根据模型解释数据的能力来选择模型。我们讨论了一个最近发表的模型，该模型对六种古人类物种的大脑和身体大小的进化及发育轨迹进行了定量预测，并将模型预测与数据进行比较，发现该模型重现了古人类进化和发育的许多方面。与直觉相反，在这个模型中，人类大脑大小的进化是一种附带现象，或是对其他事物（即生育决定性状）选择的副产品。我们的分析表明，基于模拟的推断为推断人类大脑为何进化提供了一条前进的道路。本文是西奥·墨菲会议议题“选择塑造多样的动物思维”的一部分。
