‘Fossil hominins: their discovery and context’ considers the lines of evidence that can be used to investigate what the hominin clade of the tree of life looks like. The chances of a dead hominin leaving any fossil record are incredibly slim, and even then these fossils are very fragile. Often erosion is required for fossils to be exposed. The chemical profile of the rocks, as well as the various layers of rock, can be used for dating. Absolute dating dates the rocks themselves, with techniques such as radiocarbon dating. Relative dating relies on comparing environments with other fossil sites. Climate change has affected human evolution and can also be reconstructed.