[LINK] On the unlikelihood of intelligent life

NancyLebovitz

"The Planet-of-the-Apes Hypothesis" Revisited --Will Intelligence be a Constant in the Universe?

If intelligence is good for every environment, we would see a trend in the encephalization quotient among all organisms as a function of time. The data does not show that. The evidence on Earth points to exactly the opposite conclusion. Earth had independent experiments in evolution thanks to continental drift. New Zealand, Madagascar, India, South America... half a dozen experiments over 10, 20, 50, even 100 million years of independent evolution did not produce anything that was more human-like than when it started. So it's a silly idea to think that species will evolve toward us.

"The Planet-of-the-Apes Hypothesis" Revisited --Will Intelligence be a Constant in the Universe?

If intelligence is good for every environment, we would see a trend in the encephalization quotient among all organisms as a function of time. The data does not show that. The evidence on Earth points to exactly the opposite conclusion. Earth had independent experiments in evolution thanks to continental drift. New Zealand, Madagascar, India, South America... half a dozen experiments over 10, 20, 50, even 100 million years of independent evolution did not produce anything that was more human-like than when it started. So it's a silly idea to think that species will evolve toward us.

And even if there were no unusual evolutionary pressures on individual lineages toward greater intelligence - then it would be a random walk, starting from zero. The expected distance from the origin still grows over time.

Increased encephalization has evolutionary costs - high energy expenditure and (in humans) difficult birth of underdeveloped infants due to head size. Natural selection will not allow encephalization beyond a certain size unless it has offsetting benefits, which depend on the species and its environment. So it's not a random walk (=neutral genetic drift) once you get far enough from the average, like we have.

4[anonymous]13y

Mammals evolve fast (I use them as the reference class here because they have encephalization about an order of magnitude higher than most nonmammals). Recent work seems to indicate that the entire diversity of mammals on Earth has a common ancestor after the KT event of 65 megayears ago. In an early fraction of that time, the diversity of mammals seems to have filled up a vast range of the possible body sizes and habitats. It would not surprise me if lineages also quickly explored most of the available encephalization ranges (ignoring weird feedback loops like those that lead to us) and the initial increase as those lineages were founded flattened on average.

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[LINK] On the unlikelihood of intelligent life

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[LINK] On the unlikelihood of intelligent life

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