Why did we grow large brains? There is no question that our large brains have provided humans an extraordinary advantage in the world. Still, the human brain is an incredibly expensive organ, taking up only about 2 percent of the body's mass yet using more than a fifth of the body's energy, and until about 2 million years ago none of our ancestors had a brain larger than an ape's when compared to body size. So what kicked off the push for a larger brains? One possibility is that increased smarts helped our ancestors make better tools. Another is that larger brains helped us interact better with each other. Perhaps radical changes in the environment also demanded that our ancestors deal with a shifting world. Why do humans walk on two legs? Our ancestors evolved an upright posture well before our large brains or stone tools even appeared. The question, then: Why stand and walk on two legs when our ape cousins get by on four limbs? Walking as bipeds might actually use le...
"I am enough of an artist to draw freely upon my imagination. Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world." -Albert Einstein