In a new study, researchers from Spain have determined how human beings have evolved to kill each other.

According to a team of scientists from the Estación Experimental de Zonas Áridas, murder is apparently an inherited trait in humans and primates. After analyzing data, the scientists found that 1.8 percent of great ape deaths are caused by violence between the same species, and humans account for two percent of lethal violence, especially in prehistoric times.

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During this new study, scientists studied violent traits in humans and mammals by investigating more than four million deaths among 1,024 mammals and 600 human populations during the last 50,000 years. Their results showed that one in every 300 deaths was caused by lethal violence when mammal populations began to flourish.

However, the researchers were not able to identify this two percent of human violence in our ancestors due to a myriad of factors such as genetics and environmental conditions, including the ecological landscape at the time.

Today, rising violent crimes are rampant in the United States. The FBI (Federal Bureau of Investigation) released a report on Monday indicating an increase in violent crimes by 3.9 percent since 2014. More specifically, 1,197,704 violent crimes that occurred in 2015 resulted in a whopping 15,696 murders.

Multiple studies have linked genetic traits and brain functions to violent human behavior.

This new study has been published in the journal, Nature.