Build Yourself a Brain
Convergent evolution is when organisms without any close relationship to each other evolve similar form under similar selection pressures. The most commonly quoted example is the similarities between swimming dinosaurs, dolphins and large fish such as sharks. They look pretty much the same, because that's the optimal way to build a successful marine predator. The similarities between the brains of vertebrates and octopi suggest that there are also optimal ways of wiring a biocomputer to build a smart animal.
The reason that I'm worked up about this is the implications it has for intelligent extraterrestrial life. Vertebrates and octopi have evolved similar thinking boxes independently starting from the humble neural heritage of mindless worm ancestors. It happened at least twice on Earth -- so it probably happens a lot on similar planets elsewhere!
[More blog entries about evolution, neurology, octopus, vertebrate, seti; evolution, neurologi, bläckfiskar, ryggradsdjur, seti.]