With his massive redeployment hypothesis (MRH), Anderson claims that novel cognitive functions are likely to rely on pre-existing circuits already possessing suitable resources. Here, we put forward recent findings from studies in numerical cognition in order to show that the role of sensorimotor experience in the ontogenetical development of a new function has been largely underestimated in Anderson's proposal.

In this commentary, I propose that horizontal and vertical dimensions of space are represented together inside a common metrics mechanism located in the parietal cortex. Importantly, this network is also involved in the processing of number magnitudes and environment-directed actions. Altogether, the evidence suggests that different magnitude dimensions could be intertwined with the horizontality and verticality of our world representation.

Unleashed expressions for cooperation are mainly based on the expected perceptual effects of behaviours and not the behaviours themselves. From an evolutionary viewpoint, this goal-directed mechanism allows for a comprehensive story for the theory proposed by Heintz & Scott-Phillips. Over the past 2 million years, this situated mechanism has been reused for tool use and the language development for hominids.