In the Afar Valley in 1974, a fossil, nicknamed "Lucy", was discovered and given the species name of Australopithecus afarensis. "Lucy" was uncovered by Donald Johnson, and was dated about 3.2 million years old. Many other specimens of the same species have been found, dating back to 3.9 million years ago. Another species, Australopithecus africanus, have been discovered and are very similar to the fossil "Lucy" with the exception of a larger cranial capacity and larger teeth. Australopithecus robustus and Australopithecus boisei, dating 1 to 2.6 million years ago, were also uncovered and were found to have heavier skulls and larger teeth. Fossil evidence concludes that upright walking (bipedalism) had occurred before, and not because of the enlargement of the brain. Over the years of discovers, the skulls of the fossils have become less thick, with higher foreheads, and less jutting brow ridges, thus to accommodate for the increased brain size and specialized areas for higher reasoning and for the production of speech. Teeth have also become smaller and less protruding, to aid in intricate speech and in eating different types of food. Shapes of the pelvis and the curvatures of the spine have also changed to provide more upright walking. The thick skulls and bulky teeth were best suited for earlier Homo sapiens in their environment. As the species began to inhabit the world, they evolved and adapted to the different climates and environments. They became more efficient hunters and tools became further complex. These adaptations and changes have allowed the Homo sapiens of today to enhance themselves to better acclimatize to their surroundings and to help them in the fight for survival. .