Tag Archives: anthropology

The Two Main Theories of Brain Evolution

brain evolution

Fossil records (skull size) and archeology (tools) show a clear evolution in our species’ cognitive abilities.

But, when you think about it, our current level of intelligence is far from being necessary for survival. Hunter-gathers could easily get by without abstraction, reasoning and even language.

So where does human intelligence come from? Why has our brain size tripled in the course of our journey?

Two main reasons can account for this spectacular brain expansion. In other words, humans have developed larger brains to deal with either one of the following elements or a combination of both:

  1. Their physical environment
  2. Their fellow humans

In turn, this has led to two sets of hypotheses, namely

  1. Ecological theories
  2. Social theories

Ecological theorists argue that learning to master the environment gradually caused human intelligence to evolve. Without getting into specific theories, here are four factors that might have played a role in this increase.

  1. Food: A positive correlation exits between diet quality and brain size in primates.
  2. Foraging: The increase of food sources required a better memory.
  3. Bipedalism: Tool use increased the demands on cognitive abilities.
  4. Climate: The challenges of climate change called for better problem-solving skills.

The problem with ecological theories is that these factors aren’t unique to humans, which may explain why social theories have become more popular.

Social theorists, on the other hand, argue that living in complex social grouping is what provoked cognitive development in our species. Here again, instead of going over different theories, let’s look at three important (and interrelated) factors.

  1. Social complexity: The wide range of social rules required high-level cognitive skills.
  2. Sexual selection: The choice of intelligent mates created a positive feedback loop.
  3. Language: A symbolic system fosters conceptualization and inference skills.

At the moment, the predominant model explaining the emergence of human intelligence is the ecological dominance-social competition (EDSC) theory, which is a mix of ecological and social theories.

In short, it says that an initial growth of intelligence was enough to overcome ecological pressures, which caused population to increase. This, in turn, forced humans to compete and collaborate with each other, which led to larger brains and higher intelligence.

So humans became peak learners through collaboration and competition.

Here there may be an interesting parallel with knowledge workers, whose success in the organization often comes from their high level of emotional intelligence.