Wikipedia:Reference desk/Archives/Science/2015 April 22

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April 22

What's the brain size requirement for a life form to be intelligent?

I'm curious about how small alien intelligent life could be. Binmos (talk) 02:31, 22 April 2015 (UTC)

Define "intelligent." Short Brigade Harvester Boris (talk) 02:33, 22 April 2015 (UTC)

Like human intelligence. Binmos (talk) 04:53, 22 April 2015 (UTC)

Define human intelligence. Nil Einne (talk) 12:46, 22 April 2015 (UTC)

Amazingly, it seems the brain-to-body size ratio matters far more than the actual brain size. As the intro to our cuttlefish article states: "Recent studies indicate cuttlefish are among the most intelligent invertebrates. Cuttlefish also have one of the largest brain-to-body size ratios of all invertebrates." And whales and elephants are not the supergeniuses one would expect, based on brain size alone. StuRat (talk) 02:45, 22 April 2015 (UTC)

Is it scientifically possible for a brain/animal of that size to have human-level intelligence though? There must be a limit, I imagine ant brains are too small for even the possibility of human-level intelligence, regardless of the brain-body ratio. Binmos (talk) 04:53, 22 April 2015 (UTC)

I've been reading Ant Encounters, written by a preeminent authority on ant intelligence. This is a great book if you'd like a modern approach to the science of collective intelligence. For many decades, scientists have described ant and other colonial insect intelligence as "communal." The actual "intelligence" is not stored in the ganglia of any individual; analogously, your human intelligence is not "stored" in any individual neuron. Dr. Gordon's presentation is a very fun read, and she re-explores many ideas related to localization and physiology of intelligence. Perhaps you will find her review enlightening. In particular, use caution about projecting your interpretation of intelligent behavior onto a different form of life. Gordon writes extensively on the historiography of this problem, referencing scientific and cultural depictions of ant intelligence dating as far back as Proverbs 6:6, then through the Scientific Revolution, up to the present day. Historical descriptions of animal behavior - in particular, ant intelligence behavior - seem to be deeply colored by prevailing popular ideas about philosophy, religion, politics, economics. So, today you might read about animal intelligence defined in terms of microbiology or neurochemistry, but (and this is especially critical if you're interested in the SETI angle!) there's no real reason to assume that this is even the correct framework to formulate the question of intelligence. Nimur (talk) 05:57, 22 April 2015 (UTC)

Note that while individual humans have a fair amount of intelligence, it's still the case that the collective intelligence of all mankind far exceeds that of any individual. So, in that way, we are like the ants. StuRat (talk) 19:00, 22 April 2015 (UTC)

Encephalization quotient has some info along these lines. It's not the ratio of brain size to body size, but rather the ratio between actual brain size, and that predicted by some assumptions of allometry. SemanticMantis (talk) 13:31, 22 April 2015 (UTC)

• Basically the difference between human consciousness and animal consciousness is that we have thousands of concepts for ideas of varying levels of abstraction (e.g., tree, plant, deciduous, dicot, Prunus) which we either express with spoken or gestured words (allowing us to manipulate them perceptually) and recursively through syntax. Some sort of perceptual tag is necessary for manipulating concepts beyond the animal level. (Basically an intelligent animal can do anything you can do without use of words--that is without thinking aloud in your head--they can surf, walk 50 miles to a watering hole they visited 12 years ago, and get food from the fridge, but they can't do long division.)

Those animals that do manipulate a small set of concepts (some monkeys are believed to have dozens of calls and gestures) do so with simple concatenation, and cannot handle deeply embedded and abstract thoughts like "The man I killed two days after my last birthday out of jealousy was actually innocent of cheating with my ex-wife, so I plan on killing her when she gets remarried next Saturday, unless the minister is Lutheran, in which case I will kill both her and the bastard she's about to marry on their honeymoon wherever they take it.)

I would strongly suggest Merlin Donald's two books on the subject, in chronological order: Origins of the Modern Mind and A Mind So Rare which I came across as they are highly recommended by Oliver Sacks.

μηδείς (talk) 20:13, 22 April 2015 (UTC)

Another approach would be to consider that an insect like a bee only has one million neurons while humans have a hundred billion neurons. Now, we're still far of from being able to simulate anything like a human brain using the most powerful computers we have, but a bee's brain is feasible. E.g. recently experiments have been done to control a drone using software modeled on the basis of a bee's brain. While the computer was still not as capable as a bee's brain it was good enough to control the drone. Also the most powerful supercomputer we have would be capable of controlling a machine with the full power a bee's brain. Now, suppose then that somehow a million neurons is good enough to generate human-level intelligence. That would then imply that we could make an artificially intelligent system with human-level intelligence using only the computational resources that are available today. But no expert in the field of AI believes that this is possible. Count Iblis (talk) 20:31, 22 April 2015 (UTC)

@Count Iblis: Got a cite for that simulated bee-brained drone? Sounds interesting. SemanticMantis (talk) 22:19, 22 April 2015 (UTC)

I heard that brain simulation story, but it was with some far simpler organism, with only a hundred or so neurons. StuRat (talk) 22:37, 22 April 2015 (UTC)

see here. Count Iblis (talk) 02:52, 23 April 2015 (UTC)

If you want to read about computer minds (not simulated brains, but actual electronic minds) read Jeff Hawkins' On Intelligence. He works on the same method of increasing abstract levels of thought. What matters is not computational power itself, since GIGO. What matters is how that power is structured.

From the introspective view, one should read Ayn Rand's Introduction to Objectivist Epistemology (the first unexpanded edition is probably even better for the first read). According to my undergraduate advisor (an editor of Daniel Dennett's) it's the best 20th century work on epistemology he's read. Both books work on the same perception>concept>abstraction model. μηδείς (talk) 22:56, 22 April 2015 (UTC)

The really hard part about this is that we don't have a definition for "intelligence" or a way to measure it - certainly not in non-human animals, computers or whatever. Since we can't say whether a cuttlefish or a grey parrot is "intelligent", we can't really say whether something that small is capable of whatever intelligence is. We don't have a strong understanding on what makes the human brain exhibit this trait either. In Alex (parrot) it is claimed that this particular parrot had the intelligence of a 5 year old child - comparable to a dolphin or the great apes. This is a controversial view - but if we take it as a fact, then since we clearly agree that 5yr old humans are "intelligent" - then this research implies that something a couple of centimeters across is sufficient.

But even so, Alex could only learn about 400 words - and was clearly unable to do many things that 5 year-old children can do...learning to read, to make up long, complicated stories, to memorize long passages from favorite books. We now have to carefully segregate learning and memory from intelligence - and now things get complicated.

This question is clearly unanswerable as a definite matter - but it seems reasonable that some kind of glimmerings of intelligence are possible on that kind of scale - but any kind of bright-line definition seems impossible to attain. SteveBaker (talk) 04:43, 23 April 2015 (UTC)

We actually know much more about human intelligence than one person can master, it's not true to say intelligence as such is something mystical or mysterious or undefined. The only problem, if one goes back to the OP's original question, is that he's using the term intelligence in an absolute sense, rather than in the relative sense one uses when one compares a host of organisms on a varying scale. There's no absolute point at which organisms become intelligent any more than there is a specific speed at which they become fast, size at which the become big, or point at which they become "powerful". But we can certainly explain why a monitor lizard is smarter than a nematode, and why an elephant is more intelligent than an earthworm. μηδείς (talk) 18:12, 23 April 2015 (UTC)

Faster than speed of light

If we assume that we have a very long stick, and this stick is so long that it goes through the universe to an other planet. would´t it be possible to send information faster than speed of light just by moving the stick slightly, back and forwards. /Bro(sv) (talk) 13:21, 22 April 2015 (UTC)

Nope, the fastest you can send information down such a stick is actually much slower than the speed of light; mechanically moving a stick of such a size would only be able to transmit information as fast as the speed of sound in that stick. --Jayron32 13:27, 22 April 2015 (UTC)

I think you misunderstood the question, what I meant was that you are moving the entire stick slightly back and forwards and you are communicating with some sort of Morse code/Bro(sv) (talk) 13:31, 22 April 2015 (UTC)

Yes, if I move my end of the stick, the opposite end will only move once my push reaches that end. The fastest any mechanical movement can be propagated through a medium, whether it is a push, a pull, a pulse, a vibration, a waggle, or any other movement, is the speed of sound in that medium. If I push and pull my end of the stick back and forth, it will take some very long time for those movements to reach the other end of the stick. --Jayron32 13:33, 22 April 2015 (UTC)

Like they say in the Matrix, there is no stick. Or at least, there's no such thing as a rigid body. See Born rigidity, which itself leads to the Ehrenfest paradox. This is a very deep rabbit hole and I've gone nowhere near the bottom of it. Wnt (talk) 13:35, 22 April 2015 (UTC)

There is no stick quite true. Most of an atom, and consequently, most of things, is empty space. Peter Michner (talk) 16:22, 23 April 2015 (UTC)

(EC)...And that would generate compression waves in the stick, and the message would get there at the speed of sound. This is actually a very common question/misconception, but that doesn't mean it isn't tricky to understand. See this previous question Wikipedia:Reference desk/Archives/Science/2010 October 24#Light speed and giant sticks, or this one Wikipedia:Reference desk/Archives/Science/2008 January 10#Communicating Faster than Light Using a Rotating Rod, and many other similar can be found by searching the archives using the box at the top of the page. The main thing is that in the real world, there is no such thing as a "perfectly rigid" rod or stick. Even at normal scales, there is some lag between when you push a stick and when the other end moves. It's just too short to notice without very specialized equipment. SemanticMantis (talk) 13:39, 22 April 2015 (UTC)

Thanks for answering I have been wondering about this for 3 years! I have just one small question; If we give the stick a starting velocity that is higher than the speed of sound through the stick, would the transferring speed still be the speed of sound?/Bro(sv) (talk) 17:54, 22 April 2015 (UTC)

You can strike the end of the stick at a speed greater than the stick's speed of sound, but as happens in air, a shock wave would form and the general pulse of vibration would only be transmitted at the speed of sound. There would be some slightly complex behaviour near your end of the stick, but along its general length sqrt(E/rho) rules. Greglocock (talk) 22:14, 22 April 2015 (UTC)

Unlike the speed of light, the speed of sound is relative to the transmitting medium. So yes, with respect to the stick, but no with respect to the unmoving observer. But that can never result in faster-than-light communication, because for the unmoving observer, you must add the speed of the stick and the speed of the signal in the stick using relativistic addition of velocities. --Stephan Schulz (talk) 18:09, 22 April 2015 (UTC)

Doesn't the speed of light also vary depending on what it's traveling through? ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:19, 22 April 2015 (UTC)

Yes, and it also depends on properties of the light - see Speed_of_light#In_a_medium. Often, "speed of light" is shorthand for "speed of light in a vacuum". SemanticMantis (talk) 19:48, 22 April 2015 (UTC)

In particular, the "universal speed limit" is the speed of light in a vacuum, it's possible for particles to travel faster than light within a particular medium (See Cherenkov radiation for a pretty, blue consequence of this) MChesterMC (talk) 07:36, 23 April 2015 (UTC)

It would be impossible, as planets rotate. Sooner or later, the stick would not be pointing in the right direction for the receiver on the other planet. It'd be faster to send an email. KägeTorä - (^影_虎) (もしもし！) 18:25, 22 April 2015 (UTC)

This is a very common question. See e.g. 1, 2, 3, 4, [1], [2], [3], [4], [5], [6], [7], [8], [9], etc. -- BenRG (talk) 19:22, 22 April 2015 (UTC)

I think it's important to point out that the inability to send matter, energy or information faster than the speed of light is a general property of the universe that is completely fundamental. So when you ask yourself any kind of question like this one, it's very safe to assume that the answer will ALWAYS be "No"...I don't even have to read the explanation of your question to know that this is the answer.

The only question of any importance is "Why doesn't it work?" - and that can often be interesting. In this case, the problem is that we're thinking of the stick as being a "solid object" - but we know that it's really just a rather sparse collection of atoms that push and pull each other around with various forces. The right mental model is that it's a bit like they are all connected with springs that keep them more or less the same distance apart all the time. So when you push on one end, the atoms that are repelled by the atoms in your finger go on to repel more atoms further down the rod - and the resulting wave travels down the length of the rod at a rate determined by the springiness of the spring. Hundreds to thousands of miles per hour - but nowhere near as fast as light.

But the take-away message is that no matter what devious trick you come up with - possibly involving million mile long rotating rods with magnets on the ends and electrically charged black holes spaced at intervals along them with supersonic rocket-powered weasels running along it's length signalling to each other in morse-code with flashlights...or who-knows-what other complications...you KNOW that the answer is always going to be "No!"...you don't have to worry about WHY it won't work...it just won't. It's a similar kind of deal to perpetual motion machines - or cars that are claimed to run on water...the answer is "No...it definitely won't work"...and you only need to worry about the details of how it's claimed to work if you care about WHY it won't work.

SteveBaker (talk) 04:09, 23 April 2015 (UTC)

Pronouncing XYZ "is a general property of the universe that is completely fundamental" is likely to be true in most cases but not all, thus to claim infallibility in capital letters and ignore further inquiry you divorce yourself of the scientific method. See Scientific method#Pragmatic model where it says "The scientific method – the method wherein inquiry regards itself as fallible and purposely tests itself and criticizes, corrects, and improves itself." For example, I have framed a toy model that contradicts relativity but works well enough that if I apply Occam's razor it is probably true, and unlike current theory it merits the machine that I'm building, which if it works would be progress. Learning about how the world is and not just what you happen to think it is is very much a creative process. -Modocc (talk) 06:37, 23 April 2015 (UTC)

I don't think anyone is suggesting that we should presume anything is completely infallible and in particular, that there should be no further inquiry. In fact, the nearly opposite. What is being suggested is that we should look at the existing evidence. The existing evidence really strongly suggests "XYZ (the speed of light here) is a general property of the universe that is completely fundamental". Therefore any inquiry should be based on this understanding. This doesn't mean you should completely exclude the possibility that what all the multitudes of evidence is wrong, but rather it should be way, way, way down in your list of possibilities. In this particular case, with due respect to the OP, as BenRG and to some extent SemanticMantis and others have said, this isn't a particularly revolutionary question that few people think of. Instead it's something many people think of and has been asked and answered many times over. Even for a more complicated case, it still makes sense to assume there's probably something you're missing, rather than assume you've come up with some flaw which means something widely regarded to be true as supported by a multitude of evidence is wrong. This is fully supported by the scientific method. Nil Einne (talk) 16:06, 23 April 2015 (UTC)

Assuming the theory of relativity is roughly correct, we have a choice between causality and faster-than-light communication. I like both, but causality is dearer to my heart ;-). --Stephan Schulz (talk)

{EC) Of course when you think you've discovered a flaw in something as fundemental as the second law of thermodynamics and have found free energy, it may make particular sense to investigate whether you're wrong before you spend 3+? years of your life working on something which is probably fundamentally flawed. Besides scientific method and Occam's Razors considerations, it's just common sense, there's surely better hobbies out there. Wasting so much of your time on something which is probably due to confusion or error on your part, is not likely progress. Nil Einne (talk) 16:27, 23 April 2015 (UTC)

Although I could be more diligent and commit more time to my work, I'm not wasting my time which is well spent. There is no need for strongly opinionated "take away messages", against the guidelines, which are chocked full of misplaced pedantic oughts on this science board. Modocc (talk) 17:37, 23 April 2015 (UTC)

I was fairly kind in my response, but if you don't want me to be, so be it. How you waste your time because you're too afraid to actually investigate what your doing wrong or unwilling or unable to understand it or whatever else your'e surely doing wrong, is up to you, you aren't the first person to do so and won't be the last. But as with all such people, the problem becomes when you try and mislead other people with your flawed thinking despite providing no actual evidence for your claims. So yes, what is against the guidelines is sprouting such pseudoscientific nonsense on the science desk, as you have done before and did above. Challenging people on their pseudoscientific nonsense on the science desk is well within the RD guidelines. If you want to continue to sprout pseudoscience, you're welcome to hang out in places where such people hang out (there must be hundreds if not thousands of free energy and similar forums), but not wikipedia or the RD, particularly not the RD/S. Nil Einne (talk) 00:30, 24 April 2015 (UTC)

I gave a simple counterexample that was germane to the issue that Baker raised and I made no unsubstantiated claim in what I wrote and cited our article on science. Popper would be proud. Modocc (talk) 02:03, 24 April 2015 (UTC)

"it should be way, way, way down in your list of possibilities." No, as one may have fallen into a rabbit hole. Teaching why paradigms and current knowledge applies is fine, but regarding incomplete knowledge as unassailable is not scientific. -Modocc (talk) 18:11, 23 April 2015 (UTC)

Still missing the point. I didn't say it's unassailable, and it doesn't look like anyone else did either. What I did say, is that if we have a large amount of evidence which points to one conclusion, and a tiny bit of evidence which may be misunderstood, has never been repeated, etc etc that points to another, we shouldn't throw out all that other evidence straight away. Instead you should investigate, with the recognition that all that evidence pointing in the other direction is probably right. This is fully within the scientific method, seeing paradigm shifts in every tiny bit of evidence which remotely suggests a contradiction(*) or throwing out all the evidence straight away because you don't understand something is not. (*)Particularly when it actually doesn't as multimillions of other people have found out before when they investigated, a tiny percentage of which are recorded on the internet but which still means there are probably many thousand such discussions on the internet. As is the case for the OPs question and therefore ultimately what we're talking about. Nil Einne (talk) 00:27, 24 April 2015 (UTC)

I was referring to Baker's opinionated answer and your multiple replies towards me defending him. Modocc (talk) 02:03, 24 April 2015 (UTC)

To give an example of how confusing this can be, consider if you whack on a "rigid" rod and move it by a meter, and the compression wave moves down the rod at 0.999c. So there might be, say, a 1-mm region where the rod is packed 1000x times more tightly due to the compression, moving at 0.999c, or maybe it's more like a 31.6-mm region that's 31.6 times more tightly packed. But the Lorentz contraction for anything moving at 0.999c is sqrt(1000) = 31.6, so if the second case were true, with the local atoms moving 0.999c relative to your frame, then in their own frame they're still spaced just as far apart as in the rod at rest, which means (?) that it is a rigid rod despite the obvious compression wave (?). I imagine someone must have gone much more deeply into this sort of calculation... Wnt (talk) 20:59, 23 April 2015 (UTC)

I haven't checked your math, but I'm fairly sure its no different for the compression wave which contracts than for a ship that traverses between stars. -Modocc (talk) 21:51, 23 April 2015 (UTC)

No, pressure waves in a medium and inertial motion in a vacuum are different. In the case of a pressure wave there is no physical object traveling at the speed of the wave: the atoms making up the medium travel at a much slower speed while the electromagnetic interaction between them travels (or at least updates) at c. (Compare speed of electricity.) The higher the speed of sound, the less compression you'd expect to exist at any point. You can easily compress a slinky by pushing it, but the (Newtonian) limit of an infinite speed of sound is a perfectly rigid object, which can't be compressed at all. -- BenRG (talk) 18:33, 24 April 2015 (UTC)

Which means the ships (the medium's molecules) contract less. Paradox resolved. Modocc (talk) 19:22, 24 April 2015 (UTC)