Is Intelligence Necessarily an End Result of Evolution?

This is somewhat inspired by the recent thread about evolution and religion.

Is intelligence necessarily an end result of evolution? To put it another way, given enough time (i.e. no extinction events) is an intelligent species assuredly going to arise and dominate (or at the very least become the alpha species) the planet?

My position is no, intelligence is not definitely going to arise given enough time. I had an argument about this recently with someone. His stance was that intelligence was always going to arise and dominate other species, because intelligent species are more equipped for survival. I countered this by saying that while intelligence may confer a survival advantage, it doesn’t necessarily have to. From the standpoint of natural selection, a species will survive and out-compete others if it has adaptations that allow it to breed more successfully than others. Intelligence is just a quirky by-product that seems to have developed over the last several million years among a particular primate species. This person then responded by saying that an intelligent species would, by definition, be able to out-compete all others by creating tools etc.

Then I shifted tactics. I tried to suggest situations in which an intelligent species would not necessarily out-perform others. Suppose there were an asteroid strike? The immediate destruction and ensuing cloud of debris would weed out all species except those able to avoid the blast and survive the aftermath, like tiny rodents did after the dinosaur-killing asteroid. This person then countered by saying that this may apply for a very undeveloped intelligent species (perhaps even today’s humans) but for one advanced enough, they would be able to blast the asteroid out of the path of the planet, or perhaps build advanced subterranean shelters.

I tried a few more examples like this. Disease, for instance. This person countered in a similar fashion by saying that a species with enough intelligence would be able to devise medicines to prevent species-wide extermination due to disease. Every argument I came up with was deflected in this manner.

I began to suspect that my argument may not be true after all. That is to say, perhaps intelligence is the be-all end-all of evolutionary advantages. I could swear I read somewhere a very cogent argument supporting my position, though. In the end, I had to agree to disagree with this person, but conceded that he had some very valid points.

What do you all think?


For one, there might not be enough time to evolve a species advanced enough before some kind of catastrophy wipes out its predecessors. We certainly don’t measure up to your friend’s definition of “intelligent alpha species”.

Besides, bacteria, insects and even some diseases do a lot better than us, depending on how you measure “alpha species”. I don’t think that concept really makes sense.

Just looking at the history of the world, it doesn’t seem all that inevitable. There was life on Earth for billions of years without intelligent life. And it’s not like life slowly but surely progressed toward intelligence.

On the other hand, I suppose one could argue that if one waits long enough, anything with non-zero probability has a pretty good chance of happening.

Given enough time, yes, I’d say this is a sure inevitability. Unless something happens such as all life on the planet becoming extinct due to some sort of catastrophe. But then that would eliminate all other competing traits too.

I don’t think that species with intelligence will necessarily dominate though. If humans had evolved when dinosaurs were still around (probably an impossibility but it’s a hypothetical) I doubt we’d have lasted very long. It was not our intelligence alone that allowed us to dominate. For all we know species perhaps not in the fossil record have evolved intelligence before, but did not have physical attributes that allowed them to survive.

I think our natural behaviors have just as much to do with our dominance than our intelligence. Such as our tendency to band together in small groups, protect the family group, work together to aid our survival etc.

A cockroach is extremely well adapted to life here on Earth. It doesn’t need to be smart because it is bulletproof and extremely numerous. I doubt that even given an empty niche to fill the cockroach would evolve a little roachy Mozart or a chitinous Newton, because there’s just not that much advantage to it. The roach is perfect the way it is, and very successful.

Well, I would put it another way. Given the development of a species able to articulate a concept of intelligence, it is inevitable that that species will define this trait as the end purpose of evolution and the be-all and end-all of evolutionary advantages.

Survival is, as you rightly point out, the be-all of evolutionary advantages and there are a number of contenders waaaay out ahead of us.

For most of the history of life on Earth, there wasn’t even multicellular life.

Of course intelligence is not the inevitable result of evolution. No result is inevitable.

One problem with your friends argument is that whatever advantages intelligence brings, nature doesn’t know that it does so. Evolution isn’t directed; neither intelligence nor any other trait can have any selective advantage until after it appears. There’s all sorts of potentially useful traits that animals don’t have simply because the right random mutation never came along, therefore evolution couldn’t select for it.

His argument about the advantages of technology are a side issue, because by the time technology is developed intelligence has already existed for some time. At that point, you are arguing over how long it will last, not whether it will appear. But I’ll point out there’s no reason to assume technology is inevitable; an intelligent snake or fish would be unlikely to develop it. And on a water world it probably wouldn’t be possible for anything much better than stone age technology to be developed. And for all we know most life bearing worlds are water worlds.

Under what conditions does advanced intelligence provide a significant advantage? All? Very few?

If you look at the ocean (excluding the floor, the coast and excluding mammals that evolved from land back to the ocean) it seems that intelligence is not a key strategy (I’m not an expert so go easy on me if I’m missing something here). I see lots of different types of fish, but I’m not aware of any fish that are considered very intelligent. And that environment seems relatively simple and homogeneous.

Land, on the other hand, appears to be a more complex environment and it also seems to be where advanced intelligence evolved.

This makes me wonder if a complex environment is a necessary component of evolving advanced intelligence (I know, this is full of vague notions, still I think you get the idea).

As a species, homo sapiens have only been around for a couple of hundred thousand years. Our intelligence attributes compared to other apes are vastly superior. Yet we are destroying our environment slowly, and could possibly destroy ourselves within hours. We have abandoned “survival of the fittest” in terms of physical survivability, by taking enormous measures to keep those of us with compromised genes alive to reproduce generations of homo sapiens that require intervention to survive.

In short, our time on the planet while glorious will be brief, a footnote in the history of the planet which will survive teeming with life of much less intelligence for billions of years like before we appeared.

This. Also, just because some animals appear smarter than similar creatures does not mean that their intelligence will continue to increase. Chimps won’t necessarily eventually become human-like beings 2 million years from now nor is it inevitable that dolphins will one day leave the Earth for greener pastures. Many species have developed traits only to lose them again farther ‘up’ in their evolution.

No, that just means that what constitutes “fitness” has changed. A person with hemophilia or insulin-dependent diabetes, for instance, who has the resources to obtain the appropriate medical care, will likely survive to raise offspring, but a person with the same condition but without the appropriate resources will not. So the important survival trait now is not whether one has those medical conditions, but whether one has the means to obtain sufficient wealth.

I think you are right and your fiend may be right, too. That is, it’s not inevitable for an intelligent species to evolve, but once they do, it is possible for that species to become intelligent enough to be immune from nearly all environmental conditions.

Yes, intelligence is pretty much guaranteed sooner or later. I can’t remember which book I read it in (either ‘evolution for everyone’ or ‘how the mind works’) but the author talks about how social insects, despite there only being a dozen or so of them make up half the biomass of all the insects on earth. An intelligent species that lives in a social organization has large survival advantages over dumber animals that live solitary lives. When an animal develops decent intelligence and social cohesion, it will likely improve its chances of survival.

In the book ‘how the mind works’ Pinker also talks about how attempts to outsmart other members of the social unit (so you can get the rewards of socialization w/o paying the penalty) would lead to an arms race of intellect, and he speculates that is why animals with high intelligence tend to be social. Chimps trying to outsmart each other (to gain women, power, and food w/o paying their fair share while trying to avoid being taken advantage of by others at the same time) led to human level intellect.

However, there is a difference between an intelligent animal and one that can use technology. Dolphins are supposedly about as smart as people, but they can’t build a radio because they have no hands.

Not to pile on, but this is just not an accurate description of how evolution works, or else you would have to conclude that ANY species that has any sort of social cooperation has “abandoned survival of the fittest.”

Human social structure and its consequences are a fundamental part of what we are as a species, just as they are for ants, bats, and other social animals.

Hmm, I think I can make a case for either side of this argument. But I think “No” just wins out:

Yes: Intelligence wasn’t just a handful of chance mutations. It was a complex set of physical systems which evolved to various levels throughout the animal kingdom. Many of the intermediate steps between cell and human consciousness clearly have survival benefit in themselves.

No: Intelligence does seem to go along a pretty direct line to homo sapiens. It’s not like eyes; which have evolved independently many times.
Also, humans’ cognitive abilities are leagues ahead of any living animal. We just don’t know how much of our “normal” thought processes were just random accidents with no survival advantage. A “prime” example is mathematics. Obviously a species could be sentient without maths, all I’m saying is, we humans may be freaks of nature with intelligence way beyond what the slow process of evolution would normally cough up.

I hate talk like this: implying we’re screwing up natural selection by letting the riff raff multiply. What I’d say is:

  1. Evolution: slow. Human progress: fast. Within a generation, genetically modifying our offspring could become technologically trivial and socially acceptible. Or any number of other social and technological changes could happen that will move the goalposts for evolution and change our world far more anyway.

  2. What are “compromised genes”? Say there’s a guy who’s a programming genius but has asthma. Shall we kill this guy, because that’s “what natural selection would’ve wanted”?

I had some other points, but I don’t want to waffle.

I think it’s plainly obvious that intelligence confers a massive survival advantage. Humans, as a species utterly dominate any other animal and have by far the largest range and population growth of any animal species. Whether intelligence leads to long term survivability is another question.

As far as I can see, intelligence conveys two major advantages to a species:

The ability to use memetic as well as genetic evolution - Once you can transmit ideas rather than genes, that opens you up to a whole new level of development and good mutations to flourish and thrive at a hugely increased rate.
The ability to control the environment - There’s a giant alternate space that humans have created where it remains the optimal temperature, humidity and lighting for human survival at all times and that space is called “indoors”. Our ability to reshape the environment rather than have the environment reshape us is a big plus.

However, that being said, just because something is a survival advantage does not mean it’s inevitable in evolutionary terms. Even though it only took ~500M years for life to begin, it took another 4000M more for intelligent life to arise so there’s clearly a bit of effort involved in reaching intelligence.

Intelligence is a general-purpose survival trait - making it (I suppose) a fair bit more selectable than specific, single-purpose survival traits such long necks for reaching tall vegetation.

But I don’t see why it would have to be inevitable. There are probably some worlds where life has evolved, but gets stuck at a fairly simple level due to the limitations of the environment - and there should statistically be some where conditions would permit an intelligent species to arise, but none ever happens to prevail.

It’s not clear, but it appears you’re conflating insect sociality with mammalian sociality. The two are very different phenomena.