The whole truth remains unknown, but as with evolution and the JFK assassination, we know enough to make an educated guess. We are at a disadvantage with JFK, since there was an official cover-up. Fossils are rare, and constantly eroding out of the soil and wearing down into dust, but we have found enough to determine a likely sequence of events. Monkeys led to apes, the apes started to walk upright, evolved into homonids with many ape-like characteristics, and one branch led to us, a slightly built large brained tool-using hominid, one of which became the 35th president of the USA.