Violent crime is on the rise in the United States. The FBI recently released their annual Crime in the United States report on Monday, which highlighted the increased crime rate in the states, spiking up 3.9 percent compared to the estimated number of violent crimes in 2014. Of the 1,197,704 violent crimes that took place in 2015, 15,696 of them resulted in murder.

The latest figures come just as researchers from Spain claimed that humans are predisposed to murder each other in a report published Wednesday in Nature. Researchers from Estación Experimental de Zonas Áridas (EEZA) in Spain proposed that murder may be an inherited trait in humans and primates after discovering 1.8 percent of great ape deaths resulted from lethal violence between the species, whereas humans accounted for 2 percent of lethal violence during prehistoric times.

The scientists analyzed how violent traits evolved by analyzing data of over 4 million deaths across 1,024 mammals and 600 human populations over the last 50,000 years and found that deaths by lethal violence only accounted for one in every 300 deaths during the origin of mammals. Researchers were unable to determine if the 2 percent of violence our ancestors experienced were due to genetic factors or if environmental conditions and ecological limitations played a part in the figure, but they suggested that all three instances could have influenced violence in our evolutionary past.

 

Genetic traits and brain functions have been linked to causes of violent behavior in humans in multiple studies, including a 2015 report published in Molecular Psychiatry that connected 5 to 10 percent of crime in Finland to two specific genotypes. A study analyzed the DNA of almost 900 offenders in Finland and found those with MAOA gene, referred to as the warrior gene, and a variant of cadherin 13 (CDH13) were 13 times more likely to have a history of violent behavior.