Specifically human intelligence of the kind that builds internets and spaceships has evolved exactly once on all of Earth's history, in contrast to things like eyes and wings, which have evolved dozens of times. And it evolved very recently, and appears to be due to run-away sexual selection of the kind that produced the peacock's tail.
All of this suggests that specifically human intelligence--not dolphin or bird or any other kind of intelligence that does not build internets and spaceships--has an unusually narrow bottleneck to get through compared to most other capabilities, despite the ridiculous benefits available once a species gets through it.
As such, I'm betting that we'll find life pretty much everywhere in the universe, and intelligence almost no-where. When intelligence does arise, it will likely be wildly different from us due to the essentially random nature of the sexual selection process that takes it through the bottleneck. The precursor species will almost certainly be tool-using and social, but tool use and social behaviour are both extremely common, so we could find anything from intelligent birds to octopuses.
With regard to the "surprise" that evolution can produce convergent morphology, this isn't really that surprising: genetic studies have shown that such things occur in nature. For example there are two species of coastal lizard in the Yucatan both of which have evolved an extra vertebra in their neck which were thought to come from a common ancestral population, but thanks to genetic analysis in the '90's were found to be due to convergent adaptations to coastal conditions by different inland species. Furthermore, while gene selection does occur, the basic unit of selection is the whole organism, which in most cases either reproduces, or does not.
> despite the ridiculous benefits available once a species gets through it
From an evolutionary perspective, the benefits are far from proven. On an evolutionary timescale, civilization hasn't been around that long and has had a disproportionate number of existential risks over its timescale. In the nearer term, there is also evidence for large scale dysgenetic fertility in many countries with respect to genotypic IQ. http://en.wikipedia.org/wiki/Fertility_and_intelligence
While it's true humans are the only species inventing the internet, science is also finding out other species have greater problem-solving abilities than previously understood.
The course of evolution is predictable only to the extent that the environment and its attributes are known, and that the adaptation to that environment is possible for the organism.
We might postulate evolutionary trajectory is toward adapting well enough to the environment, or only as good as it has to be for the purpose of survival and reproduction.
There's also a factor of limits of adaptation, or maxima for given evolutionary paths. A bacterium will not evolve to be an astronaut in a billion bacterial lifetimes. If it's good enough to live in my gut, or another gut, it's evolved sufficiently.
We know that environments have not been static, creating evolutionary pressure, and novel mutations then have a chance of producing increased adaptation in the changed environment. We can only assume humans evolved the brain necessary to adapt to the existing environment.
The question arising out of these ideas is our brain evolved sufficiently that no further evolution is necessary. If we are able to adapt to changing environments using the brain we have, it wouldn't need to evolve.
In a way global warming and all that it implies are a kind of natural experiment of the hypothesis. We must figure out a way to repair the damage to the planet, or adapt to it, otherwise we would predict disaster for current lifeforms including humans, and evolutionary processes will shape the successor species of the future.
>Specifically human intelligence of the kind that builds internets and spaceships has evolved exactly once on all of Earth's history, in contrast to things like eyes and wings, which have evolved dozens of times.
>All of this suggests that specifically human intelligence--not dolphin or bird or any other kind of intelligence that does not build internets and spaceships--has an unusually narrow bottleneck to get through compared to most other capabilities, despite the ridiculous benefits available once a species gets through it.
do you place Neanderthals in the same bucket of internet building intelligence or not? If not, then is it because you believe that Neanderthals weren't capable in principle to get to Internet age? If yes, then where do you make a cut-off as it seems that we have continuous range of intelligence down through ancient human species to primates to racoons...
All of this suggests that specifically human intelligence--not dolphin or bird or any other kind of intelligence that does not build internets and spaceships--has an unusually narrow bottleneck to get through compared to most other capabilities, despite the ridiculous benefits available once a species gets through it.
As such, I'm betting that we'll find life pretty much everywhere in the universe, and intelligence almost no-where. When intelligence does arise, it will likely be wildly different from us due to the essentially random nature of the sexual selection process that takes it through the bottleneck. The precursor species will almost certainly be tool-using and social, but tool use and social behaviour are both extremely common, so we could find anything from intelligent birds to octopuses.
With regard to the "surprise" that evolution can produce convergent morphology, this isn't really that surprising: genetic studies have shown that such things occur in nature. For example there are two species of coastal lizard in the Yucatan both of which have evolved an extra vertebra in their neck which were thought to come from a common ancestral population, but thanks to genetic analysis in the '90's were found to be due to convergent adaptations to coastal conditions by different inland species. Furthermore, while gene selection does occur, the basic unit of selection is the whole organism, which in most cases either reproduces, or does not.
Evolution happens at multiple levels (a topic it is fun to speculate on: http://www.amazon.com/Darwins-Theorem-TJ-Radcliffe-ebook/dp/...) and the competition between them is likely to be a focus of increasing study in coming years.