The brain in the genus Homo expanded rapidly during evolution, accelerated by a reciprocated interaction between neural, cognitive, and ecological niches (triadic niche construction, or TNC). This biologically costly expansion incubated latent cognitive capabilities that, with a quick and inexpensive rewiring of brain areas in a second phase of TNC, provided the basis for Homo sapiens specific abilities. The neural demands for perception of the human body in interaction with tools and the environment required highly integrated sensorimotor domains, inducing the parietal lobe expansion seen in humans. These newly expanded brain areas allowed connecting the sensations felt in the body to the actions in the world through the cognitive function of “projection”. In this opinion article, we suggest that as a relationship of equivalence between body parts, tools and their external effects was established, mental mechanisms of self‐objectification might have emerged as described previously, grounding notions of spatial organization, idealized objects, and their transformations, as well as socio‐emotional states in the sensing agent through a self‐in‐the‐world map. Therefore, human intelligence and its features such as symbolic thought, language, mentalizing, and complex technical and social behaviors could have stemmed from the explicit awareness of the causal relationship between the self and intentional modifications to the environment. This biologically costly expansion incubated latent cognitive capabilities that, with a quick and inexpensive rewiring of brain areas in a second phase of TNC, provided the basis for Homo sapiens specific abilities. The neural demands for perception of the human body in interaction with tools and the environment required highly integrated sensorimotor domains, inducing the parietal lobe expansion seen in humans. These newly expanded brain areas allowed connecting the sensations felt in the body to the actions in the world through the cognitive function of “projection”. 10.1111/dgd.12939 PMC11457509 39113583 Communicating Editor: Shuichi Onami This article is part of the special issue “Emergence in Biological Systems: Challenges to Bridging Hierarchies.” 1 NICHE CONSTRUCTION AND THE RISE OF HUMAN COGNITION The theory of triadic niche construction (TNC) posits that human evolution involved a specific process that accelerated the emergence of novel abilities, such as symbolic thought, language, mentalizing, and complex technical and social behaviors, which served as the basis to the rise of modern technological civilization (Iriki & Taoka, 2012 ). A key concept in TNC is niche construction, which is a set of events by which organisms select and modify components of their environments in which they and their descendants live, affecting the ecological processes and environmental factors that impact their subsequent evolution (Bateson & Gluckman, 2011 ; Laland et al., 2017 ). More specifically, TNC posits that human evolution was driven by the mutual interaction between three domains: ecological, neural, and cognitive. The ecological niche being the habitat and environment of a species and the neural niche being the biological substrate that supports specific cognitive capacities. Stone toolmaking constitutes an important milestone because it enabled the development of different types of tools for different and specialized purposes. Integrating such tools into a habitat modifies how individuals interact with and exploit their habitat, thereby creating a novel ecological niche that can evolve alongside tool complexification. This combination of hereditary (genetic and extra‐genetic) and environmental changes dominated as the main evolutionary force during that period (Iriki & Taoka, 2012 ). Tools, therefore, are not only manifestations of the human biological–cognitive niche but also an active and essential part of human development (Bruner, 2021 ). Even a comparison to Neanderthals, which show similar cranial capacity to modern humans, reveals morphological differences, with the latter having more elongated parietal regions (Pereira‐Pedro et al., 2020 ). This area has important roles in object recognition, such as during visual rotation and active object manipulation (Hsiao, 2008 ; Sakata et al., 1986 ), as well as during movement planning on a cognitive level (Andersen & Cui, 2009 ). It is also important to language and social functions (Blakemore et al., 2005 ; Simon et al., 2002 ). Object manipulation, tool use, and constructive skills are cognitive visuomotor functions that are essential for human cognition. sapiens , and modern humans, as well as the speed at which TNC‐2 emerged, its occurrence cannot be attributed solely to brain expansion. Instead, TNC‐2 more likely involved a rewiring of existing neural tissue. This process—which consisted of reusing existing neural resources of basic human abilities for novel, abstract, and advanced cognitive functions—was considerably faster and less costly than TNC‐1 (Figure 1 ). Therefore, TNC‐1 and TNC‐2 should not be seen as separate or sequential events, but as simultaneous and interactive aspects of human brain evolution. When analyzed from a contemporary perspective (post‐TNC‐2), TNC‐2 appears to require an unlikely confluence of specific factors to develop. Regardless, it is important to clarify that the relationship between these niches is not one of linear causality but rather of parallel development, as it is generally understood in the literature on regular niche construction. This milestone presumably marks the onset of obligatory tool use, which means that tools not only assisted individual needs but were also essential to survival in specific ecological and cultural niches (Bruner & Gleeson, 2019 ; Shea, 2017 ). In these new niches, the subject must understand not only the environment but also its position and role within it.