When is IQ an evolutionary disadvantage?

The evolution of intelligence

Why are humans so much smarter than animals? What is the great advantage of having such a big brain? Different theories compete to explain how intelligence evolved in humans. It is always necessary to look back to the time when the human brain developed into the most powerful on the planet.

In many of our blog entries, we explain the importance of intelligence for people today in today's society. There were also reports on the various theories of what intelligence actually is and how it can be increased. But just as important is the question of how human intelligence has developed. Why is our brain so much larger than that of other species compared to our body? How did that happen? And is it really an advantage? Researchers have long been concerned with this question. Different researchers have come up with various theories of what the factors that caused our brains to develop.

Intelligence - a blessing and a curse

First, however, it must be clarified what intelligence means in the evolutionary sense. Contrary to what might be assumed, intelligence is not a purely positive quality, but one with advantages and disadvantages. The disadvantages of intelligence are based on the fact that while a person is learning something he is at a disadvantage because he does not yet have a good strategy. An animal that is not very intelligent but is very well adapted to its environment can react without thinking. However, the less intelligent animal gets into big trouble as soon as the environment changes, as the behavior is rigid and cannot be easily changed. It is precisely in these situations that the human brain impresses with its advantages: It can quickly adapt to new circumstances and react flexibly to changes. So, as we can see, intelligence can be a disadvantage in a constant environment, but an advantage in a changing environment.

Different theories compete with each other

In order to get answers to the question of the origin of intelligence, most researchers try that living conditions to reconstruct that prevailed when the human brain developed particularly quickly. Different researchers come to different theories:

  • Hypothesis of Social brain: The anthropologist Robin Dunbar came to the conclusion through his research that our brains grew so fast that we humans stayed in larger groups. Individuals who had the intelligence to interpret and predict the behavior of other group members had an advantage over less intelligent ones. The ability to lie is also intelligent behavior that offers an evolutionary advantage.
  • Climate change: A research team led by Professor Mark Muslin came to the conclusion that the region of Africa, in which a large part of human evolution took place, was affected by extreme climatic fluctuations. The constant changes in turn required a brain that could adapt to these changes.
  • Advantage in reproduction: Another theory is that intelligence is a sign of health. The researchers explain this with the fact that many diseases are reflected in a reduced intelligence. An individual therefore tends to expect less healthy offspring from a less intelligent person.

Of course, it's entirely plausible that different reasons coincided and it was only through this interaction that the conditions were created that make our brain so unique on planet earth.


Dunbar, R. I. M. (1998). The Social Brain Hypothesis. Evolutionary Anthropology: Issues, News, and Reviews, 6 (5), 178-190.

Spiegel Online - Wissenschaft: http://goo.gl/3WqGGX

Rozsa, L. (2008). The Rise of Non-Adaptive Intelligence in Humans under Pathogen Pressure. Medical Hypotheses, 70 (3), 685-690.