We humans have unique cooperative systems allowing us to cooperate in large numbers. Furthermore, we provide help to others, even outside the family unit. How we developed these cooperative abilities and helping behavior during our evolutionary past remains highly debated. According to one prominent theory, the interdependence hypothesis, the cognitive skills underlying unique human cooperative abilities evolved when several individuals needed to coordinate their actions to achieve a common goal, for example when hunting large prey or during conflict with other groups. This hypothesis also predicts that humans who rely more on each other to achieve such goals, will be more likely to provide help and support to one another in other situations.
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Source: Phys.org