Apparently, early humans did not possess salivary amylase. The closest evolutionary relatives of humans, chimpanzees and bonobos, have either one or no copies of the gene for producing salivary amylase. A duplication event of the AMY1 gene led to the production of amylase in the saliva. The same event occurred independently in rodents. This shows the importance of salivary amylase in organisms that eat relatively large amounts of starch.