SHANGHAI, CHINA—A new study of metabolites—small molecules such as sugars, vitamins, amino acids, and neurotransmitters that represent key elements of our physiological functions—suggests that human muscle may be as unique as the human brain. Scientists from the CAS-MPG Partner Institute for Computational Biology and teams from the Max Planck Institutes found that the metabolome of the human brain has evolved four times faster than that of the chimpanzee, and human muscle accumulated metabolic changes ten times faster than chimpanzees. “For a long time we were confused by metabolic changes in human muscle, until we realized that what other primates have in common, in contrast to humans, is their enormous muscle strength,” Josep Call of the Wolfgang Kohler Primate Research Center in Leipzig told Science Daily. The team thinks that humans may have evolved a special energy management system that powers the brain at the expense of muscle strength.