Nobody knows any general way of bootstrapping intelligence; we're still working on the single example that Earth offers. And that's got speculative pieces. The best recent summary of big bang to intelligence is the series of articles in
Defining intelligence: read chapter 2 of How Brains Think.
Prospects for nonhuman intelligence: read chapter 8 of How Brains Think. Here's a sample:
Any explanation of intelligence also ought to give us some insight into other paths to intelligence than the ones followed by life on Earth: it ought, in short, to have implications for artificial intelligence (AI), for augmenting animal and human intelligence, and perhaps for finding signals from exotic intelligences. Not much can yet be said on the ``intelligence elsewhere'' subject, but let me suggest an ethological perspective that may also help us think about AI and augmented intelligence.
An intelligence freed from the necessity of finding food and avoiding predators might (like artificial intelligence) not need to move -- and so such an intelligence might well lack the what-happens-next orientation of animal intelligence. We solve movement problems, and only later, in both phylogeny and ontogeny, we graduate to the pondering of more abstract problems, acting to preempt the future by guessing what lies ahead.
There may be other ways in which high intelligence can be achieved, but up-from-movement is the paradigm we know about. It is, curiously, seldom mentioned in the literature of psychology or artificial intelligence. Though there is a long intellectual thread in brain research that emphasizes up-from-movement, it is far more common to see discussions of cognitive function that emphasize a passive observer who intellectually analyzes the sensory world. Contemplation of the world still dominates most approaches to the mind, and -- by itself -- it can be thoroughly misleading. The exploration of the person's world, with its constant guessing and intermittent decisions about what to do next, must be included in the way we intellectually frame the issues.
It is difficult to estimate how often high intelligence might emerge in evolutionary systems -- both here on earth and elsewhere in the universe. The main limitation, which makes most speculations meaningless, is our present ignorance about how dead ends in nature are overcome: it's easy to get trapped in an equilibrium, stuck in a rut. And then there's that continuity requirement: that, at each step along the way, the species remains stable enough not to self destruct and competitive enough not to lose out to a streamlined specialist.
Lists of intelligence attributes can, if carried far enough, be little better than stand-ins for giving a human IQ test to the other species (or computer). But we now can say something about what kinds of physiological mechanisms would aid a brain in guessing right and discovering new order.
We could assess promising species (or artificial creations, or augmentation schemes) by counting how many building blocks of intelligence each had managed to assemble, and the number of stumbling blocks each had managed to avoid. My current assessment list would emphasize:
A wide repertoire of movements, concepts such as words, and other tools. But even with a large vocabulary from cultural sharing over a long lifespan, high intelligence still needs additional elements in order to make novel combinations of quality.Chimps and bonobos may be missing a few elements but they've got more of them than the present generation of AI programs.
A tolerance for creative confusion, which would allow an individual to occasionally escape old categories and create new ones.
More than a half-dozen simultaneous work spaces (``windows'') per individual -- enough so that you can pick and choose between analogies but not so many as to obviate the tendency to chunk and thereby create new vocabulary.
Ways of establishing new relationships between the concepts in those work spaces -- relations fancier than the is-a and is-larger-than, which many animals can grasp. Treelike relationships seem particularly important for our kind of linguistic structures. Our ability to compare two relationships (analogy) enables operations in a metaphorical space.
The ability to shape up off-line before acting in the real world -- a shaping-up that somehow incorporated the six darwinian essentials (patterns that copy, vary, compete judged by multifaceted environments, with the more successful patterns providing the center for the next round of variants) and some accelerating factors (equivalents of recombination, climate change, islands), with shortcuts so that the darwinian process can operate at the level of ideas rather than movements.
The ability to formulate long-term strategies as well as short-term tactics, making intermediate moves that help set the stage for a future feat. Evolving agendas, and monitoring their progress, helps even more.
Another implication of my darwinian theory is that, even with all the elements, we would expect considerable variation in intelligence because of individual differences in implementing shortcuts, in finding the appropriate level of abstraction when using analogies, in processing speed, and in perseverance (more is not always better, as when boredom allows better variants a chance to develop).
``Well, in OUR country,'' said Alice, still panting a little, ``you'd generally get to somewhere else -- if you ran very fast for a long time, as we've been doing.''
``A slow sort of country!'' said the [Red] Queen. ``Now, HERE, you see, it takes all the running YOU can do, to keep in the same place. If you want to get somewhere else, you must run at least twice as fast as that!''
Lewis Carroll, Through the Looking Glass, 1871
Why aren't there more species with complex mental states? There is, of course, a fantasy nourished by the comic strips that attributes silent wisdom even to insects. But the apes would be the terror of Africa if they had even a tenth of our plan-ahead mental states.
I suspect that the reason there aren't more highly intelligent species is that there's a hump to get over. And it's not just a Rubicon of brain size, or a body image that permits you to imitate others, or a dozen other beyond-the-apes improvements seen in the hominids. A little intelligence can be a dangerous thing -- whether it be exotic, artificial, or human. A beyond-the-apes intelligence must constantly navigate between twin hazards, just as the ancient mariners had to cope with a rock named Scylla and a whirlpool named Charybdis. The turbulence of dangerous innovation is the more obvious hazard.
The peril posed by the rock is more subtle: business-as-usual conservatism ignores what the Red Queen explained to Alice about running to stay in the same place. For example, when you're running rapids in a small boat, the way you usually get pushed against a hard rock is when you fail to maintain your speed in the main channel. Intelligence, too, is in a race with its own byproducts.
Foresight is our special form of running, essential for the intelligent stewardship that the evolutionary biologist Stephen Jay Gould warns is needed for longer-term survival: ``We have become, by the power of a glorious evolutionary accident called intelligence, the stewards of life's continuity on earth. We did not ask for this role, but we cannot abjure it. We may not be suited to it, but here we are.''
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