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CronoDAS comments on How inevitable was modern human civilization - data - Less Wrong
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By the way, some birds seem to be particularly intelligent; they've been seen making and using tools.
Which to me raises a question: how much smarter could birds get? Flying is already a very demanding and difficult task - how much larger a brain could their metabolism support?
I suspect that ravens and parrots are close to this limit, and that higher-calorie birds would have to be flightless. Penguins and other flightless birds like the ostrich are, IIRC, the heaviest and largest birds there are.
This present a problem for any intelligent-bird lineage: the groups that have demonstrated a need for intelligence (like the parrots and the ravens) are very separate from the groups that have demonstrated their access to the calories/protein necessary for human-level intelligence. So how they get here from there?
Emperor penguins could be pretty smart. They have complex social lives and a diet of fatty fish. There were bigger penguins in the past too. In which case, there doesn't seem to be much of an issue.
Mm. They could be, but they're not tool-users that I've heard of. Living in social groups only puts them up with things like walruses and horses, who we never look to as possible future human-level-intelligence lineages. And the extinction of bigger penguins in the past would seem to be a checkmark against them - AFAIK, primates have trended larger over the past few million years.
The "tool use" theory of the origin of intelligence is widely discredited.
Neanderthal man was bigger than us, and had bigger brains. Extinction is too common to mean very much. Most species trend larger - until they get reset by meteorite strikes. I'm not aware of any partiularly noteworthy growth of primates. Our ancestors have mostly grown, if that's what you mean.
CronoDAS brought up the tools, not I; but I would still like to see some references about it being 'widely discredited'. Tool use seems like one of the most significant aspects of intelligence to me...
Mosst animals make very little use of tools. The (highly brainy) Cetaceans don't seem to use them at all.
More important theories inculude the social brain hypothesis - and sexual selection.
Dolphins have been confirmed as tool-users. For example they are known to use sticks and kelp in mating displays and games.
Cool. An example:
http://news.nationalgeographic.com/news/2005/06/0607_050607_dolphin_tools.html
Neanderthal brains weren't bigger than modern human. Wikipedia - Neanderthal
That dates from 1993. Here's some more recent material:
"Neanderthal brain size at birth was similar to that in recent Homo sapiens and most likely subject to similar obstetric constraints. Neanderthal brain growth rates during early infancy were higher, however. This pattern of growth resulted in larger adult brain sizes but not in earlier completion of brain growth."
Replied here but let's move the discussion to this thread: quoting:
Yes, but they also had more massive bodies, possibly 30% more massive than modern humans. I'm not sure that they had a higher brain/body mass ratio than we do and even if they had, a difference on the order of 10% isn't strong evidence when comparing intelligence between species.
If they did have significant additional brain mass, it's possible it was was used to give them really good instincts instead of the more general purpose circuits we have.
This is a quote from Wikipedia supposedly paraphrasing Jordan, P. (2001) Neanderthal: Neanderthal Man and the Story of Human Origins. "Since the Neanderthals evidently never used watercraft, but prior and/or arguably more primitive editions of humanity did, there is argument that Neanderthals represent a highly specialized side branch of the human tree, relying more on physiological adaptation than psychological adaptation in daily life than "moderns". Specialization has been seen before in other hominims, such as Paranthropus boisei which evidently was adapted to eat rough vegetation."
It's also possible that it did any of a hundred other things. Or that it didn't strictly do anything itself, but was genetically tied to some other positively selected mutation. Or it was sexually selected. Or it arose without genetic change, from environmental factors, and there wasn't enough time or pressure for natural selection to remove it again.
Why privilege this hypothesis? Other species that specialize in some way don't usually grow big brains as a result. In any case the presence of any given physiological adaptation doesn't imply the absence of intelligence. Modern human intelligence is powerful; any hominid species that happened to evolve it would have a very good chance of using it to spread rapidly. Evolution doesn't say, "this species is used to relying on physical strength, if an intelligent member is born he just won't rely on his intelligence". Every animal is always struggling for survival, no matter how and how well adapted.
I've always wondered how intelligent dogs, birds, chimpanzees, bonobos, dolphins, rats, etc. could become with say, 100 years of rigorous scientific selective breeding for intelligence.
I can't imagine any of them would reach human level intelligence (unless they had some really lucky mutations), but they might become extremely interesting, and highly instructive about the nature of intelligence.
Oh, I think they're already extremely interesting/instructive. Consider Border Collies; they can memorize <300 commands, which is pretty impressive. There aren't any grammar-producing results or indication of genuine understanding, but just the memorization points to a pretty good memory. And the border colly breed only goes back 1 or 2 centuries before it disappears in the general sheepherding/working-dog haze.
What could your 100 years of rigorous breeding do? I dunno; intuitively I feel that if silver foxes could be completely domesticated in a few decades, 10 decades ought to get border collies up to chimp-level cognition.
We don't know that a larger brain is required for greater intelligence (in e.g. birds).
I agree. But it's "easier" to evolve a slightly larger brain with the same architecture, than to discover a new, more efficient architecture.
In general we should expect a larger brain (ours consumes 1/4 of our total energy) to pay for itself in more actual intelligence; if it doesn't (the architecture can't easily scale) then the smallest (still working) brains will win.
For each species of bird, either
1) general scalable intelligence isn't supported by their brain's architecture (so you can't just grow more processing power)
2) birds lack the physical attributes to profit from any more general intelligence than they already have
or
3) it (general intelligence) just hasn't evolved yet
I don't think we should generalize from the single data point of recent human evolution. Are we sure larger brains tend to give greater general intelligence in other lineages? Has this been checked? Is the intra-species brain size variation large enough to check this in species where we already run intelligence tests?
The fact that human brains recently became unusually large can be explained by other theories. For example, it seems more likely to me that first there was a (relatively recent) mutation that significantly changed brain architecture, and only after that point did the new brains profit from growing larger. (E.g., chimps would have come before this mutation, and indeed have not experienced runaway brain growth.) On this theory, brain size only benefits the lineage with a very specific neural architecture and isn't a general rule.
There have also been other theories, some of them invoking sexual selection.
Most of the brain does tasks not directly related to general intelligence, e.g., lower-level input processing, managing the digestive system, etc.
Increases in brain size might also improve these functions and be an advantage in their own right. This would further muddy the issue if we charted intelligence vs. brain size, because we don't know enough yet to say which parts of the brain (particularly of a non-human brain) have which general-intelligence functions. Bird brains, for instance, aren't much like mammal brains, they don't even have a neocortex, so we can't just compare growth of brain areas directly. (Not to mention cephalopod brains...)
Finally, brain size directly correlates with head size, and most of the time I expect head size would be more evolutionarily significant. It controls things like eating (size of mouth and throat), defense (size of teeth and jaw), acuteness of the senses (eye size)...
Not to nitpick, but the definition of fully general intelligence is that pretty much anyone can benefit from it.
Is there any evidence that fully general intelligence exists in this world?
Depends on the definition used. You could argue that Bayes' Law is fully general intelligence.
Bayes Law is a fact/theorem which is probably useful for anyone who can understand it. But is that what you mean by intelligence? I thought it was about the abilities of an individual.
OK, then, any individual understanding Bayes' Law could be said to have "fully general" intelligence.
This is silly.
Larger brain of the same architecture.
That's what I'm talking about. What reason do we have for thinking that larger brains of the same architecture exhibit more general intelligence (in non human lineages)?
Also, what exactly does it mean for two brains to have the same "architecture" if they differ by a genetic mutation? It's not as if there's a separate gene coding for "brain size" that could mutate on its own.
If it doesn't help, and uses more energy, then it won't get kept unless it's an inevitable side effect of something helpful. That was my only basis for "larger (of same type) => more intelligence".
I don't really know anything about this topic. My claim is essentially a tautology that may not have much practical application.
Some trivia (not directly related to my original claim) I found at http://en.wikipedia.org/wiki/Brain_size:
That's true. But something helpful done by the brain isn't necessarily involved with intelligence.