Paleoanthropology of cognition: an overview on Hominins brain evolution

Abstract

Recent advances in neurobiology, paleontology, and paleogenetics allow us to associate changes in brain size and organization with three main "moments" of increased behavioral complexity and, more speculatively, language development. First, Australopiths display a significant increase in brain size relative to the great apes and an incipient extension of postnatal brain development. However, their cortical organization remains essentially similar to that of apes. Second, over the last 2 My, with two notable exceptions, brain size increases dramatically, partly in relation to changes in body size. Differential enlargements and reorganizations of cortical areas lay the foundation for the "language-ready" brain and cumulative culture of later Homo species. Third, in Homo sapiens, brain size remains fairly stable over the last 300,000 years but an important cerebral reorganization takes place. It affects the frontal and temporal lobes, the parietal areas and the cerebellum and resulted in a more globular shape of the brain. These changes are associated, among others, with an increased development of long-distance-horizontal-connections. A few regulatory genetic events took place in the course of this hominization process with, in particular, enhanced neuronal proliferation and global brain connectivity.Résumé. Les progrès récents en neurobiologie, paléontologie et paléogénétique nous permettent d'associer les changements de taille et d'organisation du cerveau à trois « moments » principaux de complexité comportementale accrue et, de manière plus spéculative, au développement du langage. Premièrement, les Australopithèques présentent une augmentation significative de la taille du cerveau par rapport aux grands singes et une extension naissante du développement cérébral postnatal. Cependant, leur organisation corticale reste essentiellement similaire à celle des grands singes. Deuxièmement, au cours des deux derniers millions d'années, à deux exceptions près, la taille du cerveau augmente de façon spectaculaire, en partie en relation avec les changements de format corporel. Les agrandissements et réorganisations différentiels des zones corticales jettent les bases du cerveau

Biologizing Gender: The canalized reproductive axis of gender, not sex.

“…This presentation on brain evolution is reasonable despite the absence of fossil records for behavior and social organization, yet, it remains partly speculative as does the paleoanthropology of cognition (Hublin & Changeux, 2022). Evolution requires both reproduction and adaptation.…”

“…In other words, sex-linked behavior patterns emanate from social mechanisms more than biologically selective origins. Because behavior and social organization leave no extant fossil records (Hublin & Changeux, 2022), it is tempting to speculate on evolutionary genetics as causal and search for evolutionist explanations to account for differences in the brain and behavior . ask do the "researcher[s] provided any evidence that the gendered behavior enhanced reproductive success?"…”

“…Since then, natural selection has undoubtedly slowed, owing to our stable lifestyles and consequent genetic fitness (Wilson, 1979). Homo sapiens brain size has remained relatively stable over the last 300,000 years but with cerebral changes that allowed for enhanced neuronal proliferation, global brain connectivity (Hublin & Changeux, 2022). Furthermore, during Hominization, the reorganization, neural proliferation, and increased global connectivity of cortical areas, along with a few genetic events that remain little understood, allowed for the development of human language and culture that set us apart from non-human primates (de Waal, 2022;Hublin & Changeux, 2022).…”

“…The cultural trajectory of our species starting 50,000 years ago was perhaps fine-tuned by "gathering around a common fire," and similar selection pressures generated by the demands on executive brain function required in adapting to the complexities of group living (Charlton & Rosenkranz, 2016). This lifestyle "may have contributed to the selection of late features of human brain connectivity, eventually referred to as belonging to a cultural brain" (Hublin & Changeux, 2022, p. 63) In Homo sapiens, the development of the baby brain continues up to 15 years of age as the cells in the prefrontal cortex blossom (Hublin & Changeux, 2022). Prolonged childhood epigenetic imprinting and social learning are unique to humans and date back to Australopiths around 4 million years ago.…”

“…Prolonged childhood epigenetic imprinting and social learning are unique to humans and date back to Australopiths around 4 million years ago. This perspective advocates that the heritability of complex traits of the connectome (and of many diseases) is spread broadly across the genome, which implies that a substantial fraction of all genes contribute to it (Hublin & Changeux, 2022) This development resembles an evolutionary Darwinian process, and by analogy with the genetic predispositions of ASD, discussing the genetic events related to the evolution of the basic human connectome, "gene networks would encode neuronal networks" that determine behavioral phenotypes.…”