Human Intelligence

Does the smartest species have the biggest brain?
Answered by Science Channel
  • Science Channel

    Science Channel

  1. If humans are the smartest beings on the planet, then are their brains the largest? Not in absolute terms, no. When comparing the weights of different animal species and humans, it turns out humans do not have the largest brains at all. As might be expected, the largest creatures usually have the largest brains. An orangutan's brain weighs only 13 ounces (370 grams), while a human brain weighs in at about 3 pounds (1,361 grams) and a sperm whale's brain at a whopping 17 pounds (7,800 grams). The correlation between brain weight and brain power really has more to do with the ratio of brain weight to body weight. The ratio of brain-to-body weight in human beings is a perfectly intelligent 1:50 (for the majority of mammals it is 1:180).

    More important than brain weight in evaluating intelligence is the size of the cerebral cortex, which is responsible for many higher brain functions such as thought processes, language and memory. In this case, if you guessed that humans are the big kahunas, you guessed correctly: We human beings have the biggest cerebral cortex of all mammals relative to brain size.

    Interestingly, while our brains far outshine those of other creatures, in terms of the size of our cerebral cortex relative to brain size, there still can be found some common ground between animal and human brains. For example, many species share with us the ancient section of the brain known as the amygdala. This shared possession is commonly used as evidence to support the notion that animals have emotions similar to humans. When the human brain is monitored for electrical activity during the experience of emotions, many of the areas that light up the brightest -- including the amygdala -- correspond to those that light up when animals appear to be experiencing emotions.

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