50 million ya

1. The last 50 million years ago have seen extraordinary diversification among flowering plants, insects, birds and mammals, including the primates

2. A diversity of apes ranged across the Old World from 22 million to 5.5 million years ago

3. By 5-6 million years ago some larger primates in Africa had come down from the trees and were walking with an upright posture.

4. A particularly well-preserved fossil that has aroused special interest is that of a young female hominin found in Ethiopia and known informally as Lucy. The species she belonged to, Australopithecus afarensis, lived in Africa from around 4 million to 2.7 million years ago. She walked upright and had a skull very like that of a chimpanzee, with a brain of around 500 cc.

5. Two and a half million years ago there were primates in Africa that were making stone tools. One species, called Homo habilis, was 90-120 cm (3 or 4 feet) tall, and had a brain with a volume of about 800cc. These animals consumed both plant and animal food.

6. From around 1.8 million years ago to 1 million years ago there were apparently several species of humans living in Africa. They included Homo habilis, Homo rudolfensis and Homo ergaster. This last was the first hominin to have an essentially modern form. They were 150 to 180 cm (5 or 6ft). Their brains had a volume of between 1,000 and 1,200 cc.

7. Remains have been found in Spain of a form of early humans that lived in Europe 780 000-800 000 years ago, classified as Homo antecessor. They had an average brain size of about 1000cc. They were probably a ancestors of H. heidelbergensis (see Figure 3).