What are three reasons some scientists think humankind began in East Africa?

There's more than three reasons as to why some scientists think humankind originated in the African continent, some of them are:

- The closest relative to the humans, genetically speaking, is leaving in Africa, that's the chimpanzee.

- The oldest archeological findings of the transitional species of hominid, the Australopithecus, are found in Africa.

- The natural conditions for the needed evolutionary pressure were right in order for the development of the hominids.