our Brain, By the Numbers

100: Number, in billions, of neurons in a human brain

100: Estimated number, in terabytes, of information it can store

1: Number, in terabytes, of information a typical desktop computer can store

2: Percentage of the body’s weight represented by the brain

20: Percentage of the body’s energy used by the brain

95: Number of diagnoses in the 1952 DSM-I, the first edition of psychiatry’s manual for diagnosing mental illnesses

283: Number of diagnoses in the 2011 DSM-IV-TR, the most recent edition

303: Highest number of random digits memorized at the 2012 USA Memory Championship, a record

10: Approximate percentage drop, in one study, in the accurate recall of random letters as a result of chewing gum

50: Percentage of times that human volunteers successfully recalled a sequence of five numbers presented briefly on a computer screen

80: Percentage of times that a chimpanzee named Ayumu succeeded at the same task