The movie Lucy said that humans use 10%. I wonder if this is true, and if it is, how is it so. Also, where can we place those people with high and low IQs in terms of percentage of brain usage?

  • This is not really a health related question, it would seem to be better suited to biology or skeptics, but even there it could possibly be closed as unprovable/vague.
    – JohnP
    Commented Feb 8, 2016 at 16:06

1 Answer 1


It certainly is not true.

There are a few reasons which might help you understand why this "humans only use 10% of their brain" is a myth:

  1. If humans only used 10% of their brains, it would be fine if one removed the 90% that is unused. However, in most cases (if not all), even slight damage to the brain causes impair of performance. This is the case of strokes, for example.
  2. The brain weights around 2% of your body weight (that's 1,5 kg), but it spends around 20% of your body's energy. If it were true that we only use 10% of our brains, such large brains would constitute a highly survival disadvantage. Natural selection would benefit humans with smaller brains -- but this was not the case.
  3. Neuroimaging shows activity in all areas of the brain, even during sleep.

There are several other explanations that try to deny the 10% myth. You may read about this at:

  • Okey..but is there a significant of the number of neurons the brain has??
    – user45563
    Commented Feb 7, 2016 at 15:27
  • I'm afraid I didn't understand your question. If you are asking how many neurons are there in the human brain, this is difficult to answer, but estimates point to something between 10 billion and 100 billion neurons.
    – Executer
    Commented Feb 7, 2016 at 16:21

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