The Independent reports that professor Conway Morris has claimed that “alien biospheres will be strikingly similar to the terrestrial equivalent and that in such biospheres intelligence will inevitably emerge”.
From statements such as this one, one would have thought that intelligence had developed many times during the history of this planet.
For instance, it’s reasonable to assume that life on planets with similar gravity and air density will have quadrupeds, bipeds and flying animals, and that eyes and ears and brains are all likely to develop.
Just think about how similar the body shapes of fish, dolphins and ichthyosaurs are, although they have very different origins.
However, it doesn’t seem to be the case that human-level intelligence has ever developed before on Earth.
This makes me wonder whether there’s something about high intelligence that makes it almost impossible as an evolutionary strategy.
I think I read somewhere that there is genetic evidence that the human race almost died out before it really got started (cannot find the link just now), so although we were eventually very successful, it was hard to get there.
Another way of looking at it is that there has only been human-level intelligence for approximately 100,000 years out of the past 500,000,000 years (the time of the Cambrian explosion), or 0.02% of the time.
I wish somebody could explain to me why high intelligence never appeared before. Surely evolution could have produced it many times, and much sooner, if only it had been a successful evolutionary strategy.