Chimpanzees and humans have one key trait in common – both are natural born killers, scientists have shown.

Evidence suggests our closest animal relatives have an almost psychopathic tendency towards violence and slaughter that is not the result of human interference. A widely held theory is chimps only turn on each other when humans disrupt their forest habitats or food supplies. The research, published in Nature, indicates this is wishful thinking. In reality, chimps fight and kill to get what they want and “eliminate rivals”, say the authors.

Competing groups of the animals go to war over resources such as territory, food or mates, the study found. And, just as in human conflict, it is often the innocent who are the victims. In the violent clashes investigated by the scientists, nursing infants were often killed, sometimes after being snatched from their mothers.

US lead scientist Dr Michael Wilson, from the University of Minnesota, said: “This is an important question to get right. If we are using chimpanzees as a model for understanding human violence, we need to know what really causes chimpanzees to be violent.”

A 30-strong team of researchers analysed five decades of data from 18 chimpanzee and four bonobo study sites in east, west and central Africa. Attackers were usually males acting together, and victims mostly males and nursing infants of other groups who were unlikely to be close kin. In some cases infants were killed but their mothers spared, despite being at the mercy of the attackers.