http://www.digitaljournal.com/science/brains-vs-brawn-how-early-humans-developed/article/385246

Brains vs brawn, how early humans developed

Posted Jun 1, 2014 by Tim Sandle
Research suggests that early humans made an evolutionary trade-off, giving up muscular strength to fuel bigger brains. This is not the view, however, shared by all biologists.
The finding comes from a report by Phillipp Khaitovich, an evolutionary biologist at the Chinese Academy of Sciences’ Key Laboratory of Computational Biology in Shanghai, China. Khaitovich examined five tissues: three from the brain, plus kidney and thigh muscle, taken from different samples over time.
The researchers recorded 10,000 different chemicals in each kind of tissue. They found that the profile for the modern human brain was very different from earlier samples, and appeared to have altered considerably. Similar effects were seen with muscle samples.
From this analysis, the researchers concluded that humans likely gave up muscle strength in order to route more energy the brain.
However, according to the New York Times, Daniel Lieberman, an evolutionary biologist at Harvard, does not agree with the team’s conclusions. He argues that the human brain developed because of brawn, based on the need to go out and gather food and to hunt.
The results have been published in the journal in PLOS Biology, in a paper titled "Exceptional Evolutionary Divergence of Human Muscle and Brain Metabolomes Parallels Human Cognitive and Physical Uniqueness."