Racism and xenophobia linked to biological fear of outsiders in Stone Age

Racism and xenophobia could have a deep-seated biological basis dating from our Stone Age past, explaining why people naturally tend to shun outsiders.

Racism and xenophobia could have a deep-seated biological basis dating from our Stone Age past, explaining why people naturally tend to shun outsiders.

For tens of thousands of years prior to the rise of agriculture in about 8,000BC, human societies lived in close-knit tribes of hunter-gatherers which survived best if they distrusted outsiders, according to two anthropologists.

Mark Pagel of Reading University and Ruth Mace of University College London believe this aversion to strangers was more than simply protecting territory but a way of ensuring the greatest degree of altruistic co-operation within a social group. Such behaviour could explain why humans are so culturally diverse, because shunning outsiders would lead to the evolution of different languages and traditions which tend to reinforce differences between tribes and ethnic groups.

In an article in the journal Nature, Professor Pagel and Dr Mace explain that for much of our history, humans have found it better to collaborate unselfishly than to live in groups where individuals are more self-centred. This altruism can be undermined by individual cheats who fail to co-operate.

It paid to have a healthy distrust of outsiders because it ensured people knew each other - to minimise cheating. "This extreme sociality can make co-operation a stable strategy resistant to cheating even when group members are not related," they say.

"But it does depend upon one key demographic feature: migration between groups must be kept low. If it is not, groups become homogenised, cheats can prosper and the driving force of group selection - difference between groups - fails."