Among most scientists it is agreed that humanity’s closest link is to chimpanzees. In 1973, the Australopithecus Lucy was discovered in the Afar Triangle of Ethiopia. Her discovery was groundbreaking. Her skeleton was nearly complete. She is an important link between humans and chimpanzees. Another fossil from around the same time is Salam, the skull, shoulder blades, and spine of 3.3 million year old child. Paleoanthropologist Zeray Alemseged spent five years carefully excavating the sandstone-embedded fossil. It reveals clues about the brain development of our ancestors. For thousands of years our brain size pretty much remained the same, but beneath the surface, tiny, key changes were happening.
Scientists are not quite sure why humans evolved from tree climbing chimps to animals that walk upright. One theory is that as the climate of lush Africa became drier, it became necessary to conserve more energy. Chimpanzees can walk but they need to exert more energy than a human to do so. They are mores suited towards walking for short periods of time. As the temperature increased, it was imperative to walk further and further distances in order to obtain food. Chimpanzees gradually evolved so that their walking became more energy efficient. The hips of humans and chimps are startlingly different. For chimpanzees the hip bones face forwards, they are in the same line as the spine. Meanwhile, in humans the hips are angled slightly. Salam may not have had comparable brain capacity to homo sapiens but the hip bones show we were starting to tilt.
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