Humans are generally thought of as the most intelligent beings to exist, as we have discovered nothing that appears to be more intelligent than us. But how intelligent are we compared to the theoretically attainable maximum? I believe that we are far less intelligent than is physically possible. This is because we possess roughly the minimum level of intelligence necessary to create a technological civilization.
To understand why this is so, we must look at how we came to have this level of intelligence in the first place. Over a period of about 50 million years, the brains of rat-like creatures evolved into the brains of chimps. This was a complex process that involved major structural changes. However, going from chimp brains to human brains only took about 5 million years and required only minor changes to brain structure, suggesting a faster but more gradual process that was unlikely to end at the exact time civilization started. So if one were to ask the question of why we stopped at our current level of intelligence, I would argue that we haven’t necessarily. Instead, we’re at this level because it allowed us to begin building civilization, a process that occurs on a much faster timescale than evolution.
The Agricultural Revolution occurred roughly 12,000 years ago. Since then, humanity has done all sorts of crazy things involved in building civilization, including at least one other major technological revolution, while evolution has only had time to make the most minor of changes. Thus, while there may still be room for evolutionary pressures to improve primate intelligence in the same way it’s been improving for the past 5 million years, the 12,000 years over which civilization has existed are simply too small for noticeable progress to occur. If a lower level of intelligence enabled the creation of civilization, then it would’ve moved too fast for us to be able to observe it in its current state with our current level of intelligence. Thus, whatever level of intelligence we observe ourselves to have from within a civilization is roughly the minimum level of intelligence capable of giving rise to that civilization.
This in turn suggests that there could be much more room for our intelligence to grow. It seems unlikely that the minimum level of intelligence that enables civilization would also be the maximum level of intelligence enabled by the laws of physics. Thus, I propose that humans are likely well below the theoretical maximum intelligence level.
Whether we are close to maximum intelligence is important for several topics. Brain-machine interfaces are much more important if there is significant room for them to augment our intelligence. Superintelligence is a greater concern the further we are from maximum intelligence. A distant maximum intelligence also leaves room for technologies like genetic engineering to possibly enhance human intelligence in the near-term. If these are all possible, then we would be wise to prepare for them ahead of time.