"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.
TL;DR: I think the main arguments in the article miss the point; radio is one of the few classic-physics-allowed means of communication, communication gives a survival advantage, it's highly likely that organisms will develop classic-physics communications and use radio long before they develop other means of communication we don't know about, and thus any species that develops environment-altering intelligence will probably gain an advantage and probably eventually have something like radios. So it's highly unlikely, IMO, that radio is a human "species-specific" trait. This comment is based on my first reading of the linked article.
From the article, the primary argument against the possibility of non-human intelligence-that-builds-radios seems divided in two parts: 1) There is no visible "trend towards" human-like intelligence anywhere on Earth. 2) Even if some species develop "intelligence" and grow that trait, the specific subsets of this that a) give sentience or b) build radios are species-specific traits of humans.
Now, 1) is rather odd and has already been deconstructed elsewhere, and doesn't support the point that strongly, if I understand any of this. A mutation needs to have a noticeable effect on survival or reproductive rates in order to fix in - and I suspect that the intersection of these and mutations that lead towards human-like intelligence is rather small, in the space of possible mutations the various earth organisms can retain. A cursory scan of wikipedia's page on the evolution of human intelligence indicates that even this is rather poorly understood, and my first impression is that many models and theories indicate that our intelligence might have been a runaway feedback loop that would not be observable as a gradual process in other species (apart from observing the gradual development and growth of the requirements, e.g. hands with grip and brain sizes for some models).
As for 2), things here are a bit weird. AFAIK, there's a limited number of methods that individual organisms can transmit information to other individual organisms. I'm willing to consider exotic things that don't resemble anything here on earth, but really, communication between organisms confers some major advantages at many levels, from telling someone else where the predators are hunting to coordinating teamwork to teaching stuff to later generations.
I mean, there aren't 2^700 different possible techniques for transmitting information across organisms, even less to another planet. You've got to send radiations / matter / stuff from A to B. Unless you magically find some way to teleport information. I doubt any organism or intelligence or goal-optimizer or probability constrainer is going to invent teleportation before ever using any form of classical radiation-based information transmission. It's not out of the realm of the possible, but AFAICT the base-minimum configuration of matter required to even entangle two particles and then measure them is far, far more complex than the base-minimum configuration of matter required to transceive light or radio signals. And I hope any apparatus that can actually FTL/teleport/etc information in means unknown to us yet is at least as complex as entangling and measuring qubits (otherwise, what the hell have we been doing? Shouldn't that search subspace have been completely covered already? Feel free to correct me on this if you have better understanding though).
So in the space of things you can do, you can have super-organisms that don't require communication to coordinate, or are just so damn smart and powerful that they don't even need to coordinate to overwhelm all pressures and enemies and predators, or some other communication-obsoleting unlikely scenario... or you have species that communicate, because the game-theoretic advantages they gain from communicating let them win more often, which translates into more of them surviving at the expense of other species or organisms.
And for that communication to happen, you've got to use one of the means that physics allows. Radio and light and other forms of radiation are pretty much hard to avoid in this field, AFAIK. There aren't 2^700 means to get data from A to B. I'm probably missing stuff, but overall if I'm playing the Natural Selection™ game: having multiple reproduction-capable individuals that communicate with eachother regularly using energy radiation / vibrations / rapid matter transfer is probably better, ceteris paribus, than not having those two advantages.
Therefore it stands to reason that in the long run, on average, planet-dominant species will have some form of communication, perhaps akin to language or perhaps more exotic, using known forms of communication at some point in their history, and there will be planet-dominant species whenever one species develops these advantages naturally. Conjecture, but that I believe reasonably argued and more likely than its complement set of possibilities.
On the other hand, based on our own experience, broadcasting radio signals is a waste of energy and bandwidth, so it is likely an intelligent society would quickly move to low-power, focused transmissions (e.g. cellular networks or WiFi). Thus the radio "signature" they broadcast to the universe would peak for a few centuries at most before dying down as they figure out how to shut down the "leaks". That would explain why we observe nothing, if intelligent societies do exist in the vicinity. Of course, these societies might also evolve ... (read more)