Humans are part of the animal kingdom. They are mammals, which means that they give birth to their young, and females feed their babies with breast milk. Humans belong to the order of primates. Apes like gorillas and orangutans are also primates. The closest living relatives of humans are the two chimpanzee species: the common chimpanzee and the bonobo. Scientists have examined the genes of humans and chimpanzees, and compared their DNA. The studies showed that 95% to 99% of the DNA of humans and chimpanzees is the same.