17 – Initial increase in brain size
2.0 million years ago
Around 2.0 million years ago, hominins in the genus Homo, began to evolve a curious adaptation: Big brains. All primates have relatively large brains, larger than you’d expect for their body size, but the degree of hominin brain expansion in the early Pleistocene (from 2.5 million until 780,000) blows these other primates out of the water. Big brains require more fuel, which means that these early hominins needed higher calorie, more nutrient rich food resources to fuel these neural processing powerhouses. This trend towards bigger brains—and enhanced cognition—laid the foundation for our species becoming the unique biological entity that we are and thus the most dominant life-form the planet has ever seen. Read more about diet and feeding behavior.
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Environmental and Climate Changes
Pleistocene glaciation 2.5 Ma