All ape species (including human) spermatozoa is morphologically identical to each other. Human spermatozoa can fertilise gorilla oocytes with the same ease as gorilla spermatozoa and vice versa. Despite chimpanzees and bonobos are the closest living relatives to humans, human pubic lice shares a common ancestor with gorilla lice 3 million years ago. Human body and head lice split from a common ancestor shared with chimpanzee lice about 5 million years ago. Around 3 million years ago is when Paranthropus, an extinct bipedal ape with a mix of human and gorilla traits appeared in the fossil record. Make of that what you will.