The following is an extract from Our Human Story, a newsletter about human evolution. Sign up to receive it for free in your inbox every month.
There are a lot of different kinds of uncertainty in science. Sometimes the uncertainty comes from having very little data. For instance, we know very little about the first couple million years of hominin evolution, because from that time period we have only a few specimens: the 7-million-year-old Sahelanthropus tchadensis, the 6-million-year-old Orrorin tugenensis and …