Neanderthal Museum
Revenge and grudges played their part in the rapid migration of humans 100,000 years ago Reuters

The dark side of human nature was a major catalyst in the rapid spreading of humans across the globe, an archaeologist has claimed. Dr Penny Spikins, of the University of York's Department of Archaeology, argues that a better understanding of mankind's dark side, in particular the betrayal of trust, is what's missing when asking why the speed and character of human dispersals changed significantly around 100,000 years ago.

Before this period, human migration was dictated by environmental events, and says that a sudden change in spreading can't be put down to environmental and ecological changes. However, Spinkins argues that after this period, humans developed changes in their emotional relationships with other humans.

In research published in Open Quaternary, Spinkins says that committing to others became more important to survival. With this came a desire to punish those who cheat, and in turn "the 'dark' side of human nature also developed".

She adds that disputes based around morality and broken trust became more frequent, which became motivation for early humans to distance themselves from their rivals. As larger social networks emerged, equipped with better hunting technologies, the ability to make allies with those far away and in turn make bigger colonies became easier.

As a result, bonds became stronger and in contrast, as did the emotion to push people out who were not liked. Spinkins says in her paper that around 100,000 years ago, when these emotions first formed, dispersal into territory that was risky and inhospitable – such as the cold of northern Europe and desert and jungle environments – became more frequent. She says that betrayal of trusts among early humans and moral disputes pushed others into these barren lands.

Spinkins: "Active colonisations of and through hazardous terrain are difficult to explain through immediate pragmatic choices. But they become easier to explain through the rise of the strong motivations to harm others even at one's own expense which widespread emotional commitments bring.

"Moral conflicts provoke substantial mobility – the furious ex ally, mate or whole group, with a poisoned spear or projectile intent on seeking revenge or justice, are a strong motivation to get away, and to take almost any risk to do so. While we view the global dispersal of our species as a symbol of our success, part of the motivations for such movements reflect a darker, though no less 'collaborative', side to human nature."