Hominin Brain Size

Question: Briefly describe the evolution of Hominin brain size and its significance. Humans have large brains, easily more than double the average size of the typical mammal. In the roughly 7 million years that there have been hominins, the brain size has roughly tripled. Most of this growth has occurred in the last 2 million years. The brain size of one of the oldest known hominins, A. Aferensis, measures approximately 550 cc (based on measurements of cranial capacity), roughly equivalent to modern apes, like the chimpanzee (at 400-500cc), and the gorilla (at 500-700cc). The expansion of the hominid brain appears to have only really begun with the genus Homo. Between 2 million and 700,000 years ago, the size of the brain of Homo erectus actually doubled. …show more content…
In the last 30,000, the brain has actually shrunk, from 1600cc, to its present size around 1350cc. Therefore, in 4 million years the brain grow to 3 times the size that it grew in the 60 million years of primate evolution that preceded it. Most human advancement occurred since the last years, when brain size was decreasing. So, it should be clear not to read too much meaning into the size of the brain. Perhaps as important as the sheer size of the brain, is the development of Broca's area and, later, Weirnke's area, as these areas are crucial for understanding and using language. Some of the most significant hominin developments, such as agriculture, art, and the awareness of death, occurred in the last 60,000 years. This is long after most growth in brain size