Study of 100 primate species finds lethal violence evolves separately from mild aggression

New research from the University of Lincoln, UK, questions a long-standing idea about the evolutionary roots of human violence, according to a study published in the journal Evolution Letters. The study was led by Professor Bonaventura Majolo, alongside Dr Samantha Wakes and Professor Marcello Ruta. It suggests that everyday aggression does not necessarily build toward deadly conflict.

The team examined patterns of aggression across 100 primate species, including humans. According to the study, species with high levels of mild aggression were not necessarily more likely to kill competitors. Deadly behaviours such as killing adult rivals or infanticide appeared to follow their own evolutionary patterns, largely separate from routine conflict.

The researchers compared five different forms of aggression, ranging from ordinary conflicts to lethal attacks. They found that different types of lethal aggression were moderately associated with one another, but that those forms of deadly violence showed little connection with mild aggression. The study states this suggests the biological and evolutionary mechanisms behind lethal violence are distinct from those that drive everyday conflict.

Majolo, Professor of Social Evolution, said the study shows the evolution of aggression follows more complex patterns than earlier models proposed. He said it is biologically inaccurate to rank species on the basis of their general propensity for aggression. He added that a more nuanced approach is needed when discussing whether humans are inherently violent.

The findings add new evidence to a longstanding debate in anthropology and evolutionary biology, according to the University of Lincoln. Researchers have long questioned whether violent behaviour is rooted mainly in deep evolutionary history or is more strongly influenced by social and cultural forces.