I read the book "Alone in the Universe" by John Gribbin recently.  He argues that the conditions that produced intelligent (sort of) life on earth are incredibly rare, so this explains the "Fermi paradox":  if there are aliens out there, why don't we see them?   (assuming as seems reasonable, that we don't). 

He gives a lot of plausible reasons for why the rareness of life.  Like, only a certain part of the Milky Way is a good home for life.  Our planet has a magnetic field that shields it from the solar wind - charged particles that stream out of the sun.  Continental drift may not be common, and it's crucial for regulating the concentration of carbon dioxide in the atmosphere, which is a kind of natural thermostat for Earth.  He thinks there were serendipitous mass extinctions of life forms that were unlikely to become intelligent, like the Ediacarans.  They were a weird kind of multicellular life that were around before the Cambrian.  Strangely shaped things.  And so on. 

Some of it is very questionable to me.  Like, he thinks that land life is much more likely to become technological, and that the reasons are obvious.  I'm not sure what the obvious reasons are and I looked online and didn't find them.  I wondered if part of the reason was that aquatic creatures would be less likely to develop hands, but then I found that octopi can manipulate objects with their tentacles.   A lot of technology wouldn't work underwater, but being underwater would make some things easier, too.  Aquatic intelligent creatures might be very good at spatial thinking since they live in 3 dimensions.  He mentions the idea of an advanced civilization putting self-replicating machines out into the universe that would colonize everything in time, and report back what they found to the home planet.  So why aren't there self-replicating alien machines on Earth, if there are alien civilizations?  But I'm not convinced that an advanced civilization would necessarily want to do this, or that it would be at all practical or feasible. 

He talks about a dinosaur called Troodon, which lived right before a 6-mile wide rock (probably) smashed into the earth, causing the end-Cretaceous extinction.  He says based on its brain size, Troodon was about as smart as a small baboon.  So the dinosaurs were on their way to evolving intelligence when they were wiped out. 

It would be interesting to speculate what an intelligent creature that Troodon could have evolved into, would have been like.  They might have been more warlike than us (NOT a happy thought) since they were carnivorous and we evolved as omnivores.  Carnivores generally seem to be rather aggressive towards others of the same species.

There are obviously a lot of pitfalls with arguing that life is rare, based on lucky accidents that produced us.  Evolution is very creative, and examples of convergent evolution show how the same solution to a problem that life is faced with, are found over and over.  Why shouldn't intelligence be a solution that convergent evolution finds over and over, on different planets, even?  And, different solutions to different problems posed by different circumstances, could be found by alien life, and the limitations of our imagination are no argument against this. 

To me, the slow speed of light compared to the size of the cosmos seems a good reason why we'd be left alone by Them.  The Milky Way galaxy is about 100,000 light years in diameter.  One could perhaps make a good argument that other intelligent life would exist on a roughly similar time scale to us, so that 100,000 years would look like a long time to Them, too. 

If it's true that conscious life is very rare, then it returns the specialness to us that science took away so much, by discovering the hugeness of the universe, that the sun and stars don't revolve around us, etc.  The wonderful nature of our world is partly explained by the fact that we are here to see its wonders - which is made possible by the enormous size of the universe. 

For me, thinking about this kind of spacey thing is a mind-refreshing relief from the humdrum forced on me by health problems.  And you can enjoy exploring the cosmos too in your imagination.

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I mentioned some things I was skeptical about, like why would it be difficult for intelligent technological marine life to develop? I didn't mention a lot of his reasons, one would have to read the book for that.

That part seems rather straightforward.  Water is a major problem for advanced tool-making.  Without fire, you can't do complex shaping and forging.

Intelligence should develop in aquatic species.  We have several good candidates for almost human-like intelligence, in aquatic species.  They just can't develop tools, beyond simple manipulation of naturally-occurring objects.

10 light years seems very optimistic.  Sure it would be easier to survive in a place than for people to evolve there - but what would be needed is a planet that isn't just habitable, but a place where a civilization can thrive well enough so it's capable of interstellar travel on its own, and has necessary resources for interstellar travel. Somalia is extremely habitable relative to most of the universe, but they aren't going to be sending a mission to Mars anytime soon. Our highly technological society can easily be disrupted enough to stop missions to outer space.

Actually, 10 light years isn't that horrible of a figure.  Look at this list.


There aren't many stars less than 10 light years from us, but each light year that you go beyond that adds to the number greatly.

10 or less - 7

11 or less - 11

12 or less - 21

13 or less - 28

14 or less - 34

15 or less - 42

16 or less - 50

Also, if you look at the Future and Past section, many stars will be getting far closer to us than any currently are, in the next couple dozen millennia.

Anyway, if our species survives another couple thousand years, We'll probably develop the technology to handle a ride of a couple dozen light years.  Hell, there are many planets that we know exist, on those first 50-something planets.  If we're willing to expand the sphere out to 20 or 30 light years, we've got to turn up something.

The biggest problem I have with the survive/thrive argument is that once you have a high-technology society, the organic end of things is fairly easily handled.  Other, rarer, raw materials become more important for success.

I'm sure even Somalia could be a nice place, with the proper organization and infrastructure.  The problem is the culture, not the land itself.




Why, though, would water-dwelling creatures have to develop technology the same way we did? 

The limitations of one's imagination aren't an argument.

Perhaps one could come up with convincing arguments for why techology couldn't be developed in waterThere are also advantages to being in water.  It conducts electricity.  I don't know of land-dwelling creatures that use electricity as a weapon, as electric eels do. And structures in water don't have to contend with gravity.  There's a huge variety of naturally evolved structures in water-dwelling creatures, because of this.  Corals, jellyfish, squids, crabs - many different ways of getting around.  Maybe structures could be built by intelligent electric eels that learn to do electroplating :) 

The same goes for a lot of the rare-earth arguments - one asks oneself, could it be done another way?  How can someone establish that it couldn't be? 

It might be possible to make somewhat rigorous arguments that intelligent life would have to evolve as it has on Earth, in some of the stages.  I'd like to see an attempt at that - or imagining how it could be done some other way. 

I think John Gribbin discussed why naturally evolved life would have to be carbon-based, somewhat convincingly.  For me, the later stages, such as his argument that rapidly changing climate pushed our ancestors into evolving intelligence, are unconvincing.  How rare are those circumstances?  Could something else in a creature's environment or society push them to evolve intelligence?  How about creatures in a marine environment, which is rich with life?  Could there develop an intelligence competition among semi-intelligent creatures?  Giant squids fighting with dolphins :) ?

What might push wolves to become capable of developing technology? 

Also, how about aggression - could a convincing argument be made that the level of aggression that is involved in developing intelligence, will prevent a species from cooperating enough to meet the species-level challenges that high-tech societies face? 

John Gribbin is well aware of how many somewhat earthlike planets there are out there; his book was published recently.  But his thesis is that MUCH more than meets the eye is required to make a planet a suitable place for intelligent life to evolve.  He makes a LOT of good, concrete points, that are rich subjects for discussion.  Just how lucky are we? 

The Intelligence Conundrun


The Intelligence Conundrum

1. Intelligence is not the goal of evolution. Evol;ution, is not goal-oriented. It's a mechanism by which random mutations in a species allow a species to adapt to a changing environment. Intelligence is not the apex of evolution, and neither is higher intelligence necessary for survival, as we can easily conclude from observing the millions of species which have adapted to their environments and survive and reproduce successfully without it.

2. The human brain is an energy hog, using a whopping 20% of the bodies total energy use. An animal would have to give up energy somewhere else in order to accomodate such a large energy drain. As has been mentioned, the environmental change from forest to savanah required hominids to adapt to a new diet. They lost their large vegetarian gut for a smaller protein gut, which freed up the energy for brain growth. As trees got sparser, bipedal travel became an advantage in walking greater distances, and it used much less energy than walking on all fours. An upright posture allowed us to see farther and detect game and danger from a greater distance. And, more important, it freed up our hands. I believe that the manipulation of objects, and greater dexterity formed a feedback loop wth the the brain. and as we became more dextrous and learned more, the brain responded by growing larger.

3. The fact that Troodon had the intelligence of a bird (and Russell's thought experiment notwithstanding) there is no reason to believe that its brain would get any larger simply because it's genus had larger brains than others of it's kind. Was its survival dependent on a larger brain? What selective pressure was there for a larger brain?The size of the hominid brain remained static for 4 million years -- until climate change, and other factors, made intelligence an advantage.

4. All animals alive today have followed a line of evolution that they cannot retrace. Wolves cannot grow hands and elephants cannot become horses; a turtle with our brain could do nothing with it. An animal cannot will a brain for itself. Evolution, if we're lucky, gives us what we need and no more.

4. Since we are the only example of higher intelligence, I have to conclude that the only animal that can develop a higher intelligence is one that is unspecialized in terms of habitat and diet, has an unspecialized body type, is comparatively weak and has no specialized defence. We evolved as a result of the history and composition of our solar system, the history and composition of our planet and the history of our evolution -- including mass extinctions. Every single factor would have to be there in order for us to be reproduced  again. Could a man-type animal evolve on other planets? I think it's very unlikely -- just as I believe that elephants and giraffes will never evolve on another planet.

Thanks, this is the sort of analysis I was looking for. 

Intelligence is not the goal of evolution.

However, evolution has tended to produce more and more intelligent creatures over time, by convergent evolution - for example, octopi, people, dolphins ...  Some intelligence is clearly adaptive in many different circumstances.  Intelligence has clearly helped humans adapt to many different environments.  

Maybe we were just VERY lucky to have been through a kind of evolutionary forcing, rapidly changing environment etc., that caused human-level intelligence to evolve quickly, and soon during the evolution of life.  If that evolutionary forcing hadn't happened, maybe evolution would gradually have come up with human-level intelligence. 

And yes, human-level intelligence would have to evolve along with physical characteristics that allow it to be useful, like dexterous hands that originally evolved to allow monkeys to move around in trees (arboreal big cats like leopards don't have hands, but maybe being a predator they don't need to move so quickly in the trees).

Wolves cannot grow hands

With the right evolutionary pressures maybe they would, say if they became arboreal. 

Hands of a sort are also convergent evolution.  Octopi can manipulate things with their tentacles, which presumably originally evolved to grab prey.  Elephants have some dexterity with their trunks.   

We're also very visual, something that was important in trees and is important in how we think.  When you're making something, a visual imagination helps, and maybe this evolved from jumping around in trees - you have to imagine what the place you're going to land on will look like.  Marine animals also live in a 3-D world, maybe this would develop a visual imagination for them too. 

Perhaps standing upright allows for a large brain too, otherwise a lot of muscle would be used just to hold it up. 


Is this true of dolphins, is their large brain an energy hog?  Perhaps in a rich marine environment, there's a lot of food available so they don't have to worry about it? 

I wonder what dolphins use their large brain for - my impression is that it's partly to communicate.  Of course developing a brain to communicate with others of the same species is another way to use a big brain.  Or to train one's offspring.  I wonder if dolphins have culture that they pass on to offspring, as chimps do. 

I read once that the sense of smell was important in the development of mammalian consciousness and the cerebral cortex.  Maybe the early mammals developed their sense of smell from sneaking around at night to avoid being eaten by dinosaurs. 

John Gribbin said a lot about serendipitous extinctions enabling humans to evolve - such as the extinction of the dinosaurs, which allowed the mammals to "come out of the closet". 


Neanderthals weren't weak.  But perhaps more specialized than we are. 

Luara, I,ve been very busy, but I will respond in the next day.

Evolution has produced intelligent species, but nothing like man. There is no evidence that any animal is getting smarter than it has been in the past. A large brain does not mean a proportional increase in intelligence. In dolphins and whales some of the brain could be used to deal with the physiological changes during a dive, another part could be used for cooordinating the functions of such an enormous body.

Octopus brains may be considered convergence, but what is the point you're making? If intelligence was the driving force in evolution, then there would be more animals today which would be as smart as man. We are a late addition to the tree of life.

If wolves had to become arboreal in order to survive, they would first become extinct. Evolution does not add parts to an organism, it only modifies what is there. You seem to imply that if an animal did "this" or "became this", then it would get hands and evolve a large brain. You ignore the fundamental principles of evolution: Random mutations >>> selection >>> evolution.

Let's say that an animal, man, uses 100% of it's energy to maintain itself. The brain requires 20% of the total. The heart may require 15%, the gut may require 10% etc. In order to make another organ larger, you need to borrow the energy from another part of the body. Eating a lot will still only distribute energy to the organs in specific proportion: 20%, 15% etc. And all excess food will be stored as fat. You want a bigger brain, you have to free up energy elsewhere and modify another body part to use less energy.

"Comparatively weak": Early man had less hair to protect him against the elements; he had no large, sharp teeth with which to kill his prey or protect himself, and no sharp claws. He would not stand a chance against any large predator or a pack of dogs; he was not fast enough to outrun them. He was pretty helpless -- without tools. And a brain.

However, the maximum intelligence of creatures has generally increased during evolution.  It takes some time for intelligence to evolve.  Therefore, a creature alive with a certain level of intelligence (tends to) imply that life has been there for a certain time.

What I was saying is that perhaps the evolution of human-level intelligence is a rare accident this early in the process of evolution. 

Maybe the pattern so far, that the maximum intelligence of creatures alive increases over time, holds generally.  If people hadn't evolved, maybe human-level intelligence would more gradually have evolved, from some other creature.   Maybe the answer to the Fermi paradox is that in a billion years, our galaxy will have a large variety of intelligent species, that evolved in a more common, gradual way.

The brain size of hominids increased quite suddenly.  I read that there was a genetic mutation involved, I think it turned off a gene that was controlling brain size in our ancestors 2.5 million years ago. 

If anyone has a good argument for why the evolution of human intelligence has to happen as a sudden jump like this, I'd be interested to hear it.  


No more proof of that than of the assertions of intelligent-design people that various features of animals couldn't have evolved by natural selection. 

I don't know why you think this; is there anything about our hands that you can show couldn't evolve from a wolf's paw?  Anything that wolves have lost in the evolutionary process since we diverged from them in evolution, that would be unlikely to evolve again?    Cats, which are related to canids, have more flexible claws. 

There are dogs that are good at climbing by the way :)  I saw a funny movie once of a climber, showing his small dog scrabbling up rocks with him in a way that was amazing for a dog. 

A large brain does not mean a proportional increase in intelligence.

I've seen the ratio of brain size to surface area used as a rough index of intelligence.  Since the surface is the main way an organism interacts with its environment.  I think this ratio gives a rough indication of how intelligent a creature is.  

I've wondered about intelligence evolving in a group, as in social insects like bees where the whole colony can be considered a being that knows things that individual beings don't. 

One might argue that there's a basic limitation on the increase of intelligence of a group being (like a bee colony) relative to the intelligence of the individual members, because the individuals are a certain distance apart, and that places limits on processing speed.  Perhaps a computer scientist could show somewhat rigorously what that limit is.

I've wondered about intelligence being developed in a social way, like in a wolf pack - say the individual members learned to cooperate in manipulating things with their teeth. 

Luara, I really don't want to go on with this topic but move on to somethig else. Thanks :)







OK.  There are some arboreal canids by the way:  the gray fox which according to Wikipedia has strong hooked claws for climbing; it goes up trees to escape predators and to get food.

Also the raccoon dog is arboreal.  It isn't a dog, rather a different species close to the common ancestor of the canids.

The order Carnivora apparently evolved from ferret-like creatures like Miacis that were arboreal. 

Yes, a number of animals  live in trees either in whole or in part, but this doesn't necessarily result in hands or greater inelligence. But your contention that wolves would evolve hands if they became arboreal made no sense to me in the real world. And I said that if they needed to become arboreal to survive -- they would become extinct.

Now imagine yourself observing wolves in the northern boreal forest and tell me what happens that would make arboreal life the only way that they could survive?

And remember, boreal forests are coniferous, not a tree easy to climb without claws. 


Here is a current Discovery article depicting a number of scientists as confident that an Earth twin will be discovered next year. Per the article:


And there are probably many alien Earths out there to be found in our Milky Way galaxy, researchers say. "Estimating carefully, there are 200 billion stars that host at least 50 billion planets, if not more," Mikko Tuomi, of the University of Hertfordshire in England, told SPACE.com via email. "Assuming that 1:10,000 are similar to the Earth would give us 5,000,000 such planets," added Tuomi, who led teams reporting the discovery of several potentially habitable planet candidates this year, including an exoplanet orbiting the star Tau Ceti just 11.9 light-years from Earth. "So I would say we are talking about at least thousands of such planets."





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