Early examination of the biological roots of psychological illnesses included the discovery that a common type of sexually transmitted disease, could produce abnormal behaviors. these included hallucinations, delusions, and changes in mood and personality.

The accompanying figure shows the percent of selected dna sequences that match between a chimpanzee and other primates. these data support the hypothesis that the figure shows the percentage of selected d n a sequences that match between the chimpanzee and other primates. the human has an almost 98 percent match, the gorilla has an almost 97 percent match, the orangutan has a 96 percent match, the gibbon has an almost 95 percent match, and the old world monkey has an almost 92 percent match. the accompanying figure shows the percent of selected dna sequences that match between a chimpanzee and other primates. these data support the hypothesis that the figure shows the percentage of selected d n a sequences that match between the chimpanzee and other primates. the human has an almost 98 percent match, the gorilla has an almost 97 percent match, the orangutan has a 96 percent match, the gibbon has an almost 95 percent match, and the old world monkey has an almost 92 percent match. chimpanzees and gibbons are the most closely related the chimpanzee's closest surviving relative is humans orangutans are the primates least closely related to chimpanzees old world monkeys and gibbons are the most closely related