The neural basis of human tool use

Area of Science:

• Neuroscience
• Evolutionary Anthropology
• Cognitive Science

Background:

• Human tool use is complex and diverse, distinguishing us from other primates.
• Previous research has not fully identified the neural underpinnings of spontaneous, diversified tool use.
• Understanding the evolution of tool use offers insights into human cognitive development.

Purpose of the Study:

• To propose a neural basis for human tool use, specifically focusing on the left anterior supramarginal gyrus (aSMG).
• To investigate the evolutionary origins of this specialized tool-use system.
• To differentiate the neural systems for object grasping versus tool manipulation.

Main Methods:

• Review of existing neuroimaging and evolutionary data.
• Comparative analysis of human and macaque brain activation patterns during tool-related tasks.
• Hypothesizing evolutionary pathways based on hominid fossil and tool industry records.

Main Results:

• The left anterior supramarginal gyrus (aSMG) shows specific activation for observing and executing tool actions in humans, unlike macaques.
• aSMG integrates visual, semantic, somatosensory, and motor information relevant to tool use.
• A distinct 'artifactual system' for tool use evolved in humans, separate from the 'biological circuit' for grasping.

Conclusions:

• The aSMG represents a human-specific neural adaptation for tool use, likely evolving from a duplication of primate grasping circuits.
• This specialized system emerged during hominid evolution, potentially linked to early tool industries and the development of bipedalism and language.
• The artifactual system is crucial for understanding tool causality and underpins technological advancement.