In what habitat types did our earliest ancestors live? This is a fundamental question in human evolution as many of the features that are regarded as making us special (such as walking two legs, making and carrying tools, etc.) have been related to our move from the forests to the grasslands several million years ago. When we describe where our ancestors lived using the evidence from the fossil record (such as fossilised plants and animals) we often end up describing their habitats as ‘mosaic’ (mosaic in this sense means a mix of trees, grassland and open water). But did they really live in such environments, or is the mosaic just a result of our not being able to refine the information we get from fossils. For example, the remains of a hippo and crocodile would suggest open water, while a giraffe would suggest trees, and a zebra the open plains. If we find them all together as fossils, is that evidence of a mosaic, or just that our fossils are all mixed up?
Our project is stepping back from the fossils and taking a ‘top-down’ approach (literally), using remote sensing and satellite images to examine parts of Africa to see where the mosaics are, and at what scale. Scale is really important in these analyses – after all a mosaic for a beetle will be much smaller than the mosaic for an elephant. The great advantage of remote-sensing is that we can scale up or down, depending on our question. We are classifying the landscapes into a number of distinct landcover classes (such as dense woodland, open grassland and open water) and then examining where we find these landcover types and where in Africa these ‘mosaic’ landscapes exist. These results, of where the mosaics are and which factors may help them to form, will then be used to help us to interpret the past.