Why man-- and only man?

Great Debates
1

This is something that I have long questioned, and I’m hoping that one of the scientific minds here can teach me something.

I accept the evidence that homo sapiens evolved slowly over millions of years, related to today’s primates but evolving on a separate track from a common, much earlier, ancestor. I’m aware of the statistics showing that our DNA and a chimpanzee’s DNA are something like 96% “shared” and the many traits we share with them. And I see all the celebration of the chimp ( and the dolphin, as another example ) being hailed for their incredible “intelligence.”

My question, if I could summarize it in a sentence, is:

Why, (or, How) if man is simply a mammal, like other mammals, did our level of intelligence so dramatically surpass that of any other animal who has ever lived on the earth?

My point is, “we” got a relatively “late start” on the evolutionary ladder, yet it is we who – for instance right now – are communicating in real time, across the globe, in just one of hundreds of written languages we’ve conceived, on computers that sprang from our minds, using software written for those computers… etc. (Yet alone considering advances like harnessing the power of electricity, nuclear power, or conceiving of and then developing vehicles that can actually escape the atmosphere of our planet and navigate to the surface of other planets.)

Meanwhile, the chimpanzee is being hailed for his use of “tools” when he sticks a blade of grass in a termite mound and pulls it out to eat those that cling to it… while we’re docking the space shuttle up to the Hubble telescope.

Why the disparity between the vast capabilities of humans compared to even the “smartest” animals ? Shouldn’t some creatures other than us have come up with something more advanced than simply eating and reproducing in the environment they’re born in? Even allowing for the bias of “judging” other animals based on our standards, as if they were absolutes, we’re left with the inescapable fact that no other animal besides us has ever invented and then manufactured even the simplest machine. The qualitative lead we as a species have over whatever is number two is completely off the scale.

This disparity is what intrigues me. Again, I accept that man is “just” a mammal – that doesn’t bother me or make me feel “insignificant.” But it’s one of the (few) things I have trouble reconciling when I consider evolution and how it took place. I suppose I should admit to a bias going in, for I am not looking for a theistic answer here. “God made you smart-- it says so in the Bible” isn’t going to cut it. :slight_smile:
Hopefully, one of the scholars on this board with expertise in a related field of study (anthropology, biology perhaps?) can fill in this gap a little.
Otherwise it’s another expensive trip to the bookstore – heheh

2

I think brainpower just wound up being a very viable evolutionary pathway- humankind’s existence, and sheer population has demonstrated that you can have a creature which is relatively frail, but gifted with a lot of intelligence and so is able to bank on that for survival. It just seems to surpass many other creatures who get by on size, strength, speed, senses, etc.

Plus intelligence is a very flexible strength- while most animals have practical limitations on how fast, strong, big, etc they can get, human intelligence just seems to keep going. And the smarter we get, the easier it is for us to survive and make more people.

3

I’ve read one theory that claims man killed any competition that he deemed a threat. Primates with similar traits and Neanderthal man in particular were seen as competeition for scarce resources and were simply destroyed by the bands of “humans”.

Modern man was not descended from Neanderthal, although they were closely related. (according to what I read) I’ll dig around and see if I can find a cite.

Biologically speaking, it is a lot more complicated than it seems. There are specific capabilities that humans have that are not found in any other creature. Sure some cetaceans have incredible intelligence (comparably speaking) but they lack other features which limit their evolution. The same thing with other primates.

Then again there is that theory that WE are just genetic experiments conducted by aliens on the indigenious life THEY found on this planet so many years ago. :wink:

BTW intelligence is not necessarily determined by “brain size”. The better indicator of intelligence is surface area. While it may seem that the larger brain would obviously/naturally have more surface area. It is the amount of sulcus/pl. sulci, grooves on the brain surface that increase the surface area. The more grooves the more area.

The way the human brain functions and the vastly superior connections within it. Highly developed areas of reason. etc.
This could go on indefinitely.

When ALL of these advantages showed up in ONE species, well it was inevitable that said species would dominate. AND if human nature is any clue, it is entirely possible and believable (IMHO) that we would have destroyed any “threat”.

Also believable is the idea that primordial man would have included/absorbed any other similar primate species into the clan.
Whether there would have been offspring really wouldn’t matter. The “others” would have either died off or bred out.

I’d love to continue but I gotta go. :slight_smile:

4

Mostly because of luck. The evolution of intelligence (meaning mostly problem solving and communications) needed a lot of factors. One of the most important was social animal. Animals living in a society tend to have better communication skills, which helps with the development of intelligence. A lot of mammals are no social animals, so for the most part we can knock them off right away.

You also need size. A small mammal just won’t have the cranial capacity for substantial intelligence. So you can knock off another group right there.

You also need a fairly rapidly changing environment, where skills must be developed extremely quickly and new challenges must be overcome without waiting for gradual evolution. This is where humans come in. The Ice Age caused a ton of environmental change fairly rapidly. And it wasn’t constant change, it was constant and rapid fluctuation. The world temperature would cool, forests would be devastated, grasslands would spring up, and then forests would come back and be devastated again. Fires would have been fairly constant, only adding to the problem
Droughts were also common in certain areas.

This meant that only the most clever species were going to survive and a brain with the capacity for problem solving, adapting to novel situations and foresight was going to be a huge advantage. We are basically the descendants of those apes that were able to adapt quickly to the changing environment.

5

Um…dolphins are smarter. No wars, they don’t abuse their kids (that I know about, anyway) and they always seem to be having such a good time. Technology is not the only measure of intelligence, IMHO.

My eldest wrote a poem about dolphins, their world and the way they live, the closing line of which was: “I would give up hands for this.”

6

Dolphins aren’t smarter. Hell, anytime on my ship we had to pump out the sewage, the dolphins would come by for a free meal.

German websites aside, humans don’t do this.

7

I suspect that the rapid expansion of the brain in the Homo line was the result of an evolutionary feedback loop. Because the brain requires an extrordinary amount of high quality calories to maintain, it has to earn it’s keep, so to speak, to make it worthwhile. It was most likely luck or environmental factors that drove early man to become the omnivore that we are, adding much more protien (and fat, such as bone marrow) to out diet. This allowed the brain to expand even more, and expanding tool use and social skills to imrpive our diet even more-- thus the feedback loop. Not dissimilar to how the peacock’s tail got as big as it is.

The chimps we see today are simply those members of our early linneage that weren’t subject to the same luck or environmental pressure that our ancestors faced. Although chimps have surely spent the last 6 million years evolving in their own direction, brain expansion does not appear to be the path they took.

8

Neurotik-

There has to some factor, beyond those you outlined, to explain the huge disparity in intelligence between man and “number two on the list.”

If we take, say, lemurs as an example… they are highly social animals, and have a very effective vocal and non-vocal communication system. They would theoretically benefit from most of the same physical characteristics we enjoy that help us realize the full potential of our intelligence, such as grasping fingers and unrestricted locomotion within their environment. Madagascar, their sole habitat, was affected by all of the global temperature shifts that Cro-Magnon man was adapted to.

Even if we can successfully argue that the evolution of lemurs differed enough from the evolution of homo sapiens to justify a difference in intelligence, it fails to explain the vastness of the difference. Again, we’re talking about using a rock to bash open fruit versus mass-producing the internal combustion engine.
The cranial capacity argument seems sort of dodgy to me. Bears, lions, and bison all have at least as large an area of their skulls available for brains as we do, and the space shuttle designs springing from those species have been rudimentary at best. :slight_smile:

To put the question in my OP a different way: How did it come to be that only one animal in all the millions of species that live or ever have lived on this planet, from golden retrievers back to Tyrannosaurus Rex and his ancestors,
could come to stand out in such dramatic isolation from all of the others?

Wouldn’t “luck” have produced some technological advancement for just ONE of the other species, especially ones that are the closest equivalents to us in terms of genetics? (For instance, if the lemurs in our example above had figured out how to cut down trees and use them to construct shelters or “huts” to protect them.)

Instead, we just see us… and all of them.

Why?

9

I think there is one obvious ability which humans developed but which exists in no other species (at least not to the extent that it does in humans, anyway) which made all our discoveries and inventions possible: language.

As for how language evolved, the picture is still fairly incomplete. But the recently discovered FOXP2 gene, which is responsible for the development of grammar, is a start. This gene exists in other mammals besides humans, but underwent a mutation in humans, if I remember correctly, about 100,000-200,000 years ago.

10

NoCool, MrMoto is right, and furthermore Dolphins aren’t so civilized:

from here

*Researchers found that the image of the peaceful, spiritual dolphin were misleading. Dolphins were involved in savage attacks on porpoises and other dolphins, as well as the kidnapping and “gang rape” of dolphin females from other groups *

11

No, not really. Why would there have to be?

Why didn’t lemurs evolve like humans? Because they didn’t need to. It’s not like the lemurs that are around today are the same ones that were around a few million years ago. The lemurs of today didn’t evolve intelligence because their ancestors didn’t have the same circumstances.

Consider this. An australopithicean was probably not much more intelligent than a modern chimpanzee. The main difference is that an australo was bipedal, and this developed when a proto-ape split into two groups. One that stayed in the trees (chimp line) and one that moved onto the ground (human line). From that point forward, they were subject to different pressures.

There were more splits. Homo Habilus lived alongside another hominid called Paranthropus something or other. Paranthropus, however, had evolved jaws, teeth and digestive organs that allowed it to eat all sorts of good, but tough, foods. Habilus, on the other hand, didn’t evolve that way. So it had to rely on scavenging - leading to a more meat based diet. This greater meat based diet was key to developing a larger brain, which was necessary to evade other scavengers like big cats or wolves or whatever. Different pressures resulted in different outcomes from different species that were probably the same a few thousand years before. Paranthropus was killed off by an Ice Age that wiped out the grassland diet it relied on, while Habilus was able to weather the change.

Lemurs didn’t develop the same intelligence because they were able to survive some other way.
**

**
Sure it does. If the lemur didn’t need to, then they didn’t. Humans have also been in a sort of feedback loop. More intelligent and innovative humans would beat out less innovative humans in competition. If lemurs didn’t rely on cleverness and innovation to survive, then that feedback loop wouldn’t be there and other skills would have been improved.
**

**
Not really dodgy at all. You can see it in the fossil record. As humans have gotten more innovative, their cranial capacity has gotten larger. But it’s not the only factor, that’s why bears, lions and bison haven’t been as intelligent. Their ancestors didn’t have the building blocks for them.
**

Because they didn’t have the same circumstances or the same building blocks.
**

**
I don’t think you understand evolution all that well. The closest equivalent to use in terms of genetics would be chimpanzees. They didn’t evolve the same way because they lived in a different environment and didn’t undergo the same pressures.

It took millions of years to get to where we are now. It’s not like a proto-ape just walked out and invented stone tools or something. Lemurs didn’t evolve intelligence because they didn’t have the diet, physiology, environment and evolutionary pressures that that need to do it.

12

The difficulty I have with “luck” as an answer ( or “chance”, to use a phrase that, for whatever reason, seems more palatable) is that “it” has happened only once in however many millions of “opportunities”, ie, species, that have existed on this planet. Moreover, the degree to which “it” happened is so staggering that the difference between “it happening” and it “not happening” seems to deserve a more thorough explanation than random chance.

It’s not just that I can’t conceive of a million-to-one shot happening; surely it can, or people wouldn’t win lotteries. :slight_smile:

It’s just that when you factor in the disparity between our intelligence and every other beings, the nagging question of “why?” isn’t so easily answered. If you tell me that there’s a two million -to- one chance that a toddler could hit a baseball out of Yankee Stadium, I’d be inclined to accept that, or even consider the odds a bit generous. Still, I would have to agree that it was within the theoretical realm of possibility for it to happen. If that toddler hit it deep into New Jersey, though, (an admittedly imperfect analogy to the intelligence difference we enjoy over other animals) I’d seek a little bit better explanation than, “Well, it was a one in two-million shot, and there it just went.”

The inference that lemurs (as an example) didn’t “need” to evolve any more fully leaves questions unanswered for me as well.

It could be argued that we didn’t “need” to develop anywhere near the intellectual capacity that we did. Once we had evolved to a point where we could shape our surroundings to provide shelter, construct tools that allowed us to maintain our diets, form societal groups that bettered our chances for survival, and the like, we already were the dominant form of life on the planet. Theoretically, we could have simply sat back on our evolutionary laurels, content that we were at the top of the pyramid, and settled into millennia of status quo. After all, we didn’t conceptualize and accomplish powered flight, for instance, because we “needed” to fly. We wanted to – because our brains told us that it was possible.

Similarly, I’d argue that lemurs (among others) certainly “needed” --or at least would have benefitted from-- advanced evolution, just as we did. That is , the “pressures” on them to do so were/are no less pronounced than the “need” which propelled us forward. The ice age and other environmental upheavals affected all things alive at the time, not just the men.

I think tourbot hit on language as being critical in explaining how and why we reacted to environmental changes so much more effectively than our “peers” in the animal kingdom. It seems to me that the ability to speak and write a language (and preserve a record of it for future readers) can’t be over-estimated as an explanation for the intelligence gap.

Lastly, maybe I don’t understand evolution “all that well.”

I’d like to, and that’s why I’m here. :slight_smile:

13

The thing I think everybody overlooks about evolution is this: We weren’t really competing against other species/the environment to stay alive and reproduce (we were, of course, but …), we were competing against OURSELVES–other humans within our species. With our extremely large, complex social groups (whose precursors you can see in the smaller, social bands of chimps and gorillas), we needed brains to keep friends, family, rivals, and potential mates straight, and–more importantly–to figure out how OTHER people are thinking/reacting so we can outsmart them.

Evolution produces lots of solutions to the same problem (making sure your genes are passed on)–some animals fight others of their species for mates, some try to put on the best display to attract females, etc. We happen to (mostly) try to outmaneuver each other.

14

because of woman of course… (sorry couldn’t resist)

15

Funny I didnt see any mention to language. Our vocal cords might have been one of the most essential “tools”.

By passing to the next generation knowledge thru not only physical teaching but language we were able to “accumulate” knowledge. By communicating we created complex groups and eventually societies… and coordination.

As for the competition. Wolves and dogs had similar hunting grounds as we did and instead of wiping them out... we domesticated the dog. Eventually thou another intelligent animal might have constituted "undue" competition and might have been wiped out thou not necessarily.

Its not the fact that we were late starters that really matters since in a short time we might be wiped out also. Many sucessful “late starters” have been wiped out. If we were a duck based predominant species we would be congratulating ourselves for being Avian and Aquatic as well… and thinking how curious our feather ruffling allowed for complex information exchange. We “lucked out” in having the combination of hands, brain, vocal cords and being bipedal.

16

Out of curiousity, how do we know that human intelligence has “dramatically surpass[ed]” that of all other animals on the earth? I mean, no one here has quizzed the gorillas on their philosophical leanings, have we? And maybe camels are mathematical geniuses that merely haven’t bothered to tell us how smart they are.

17

Well, it’s not entirely random chance. There were environmental pressures. But that those pressures came along and affected the right species (early hominids) was random chance.
**

Eh? Are you talking about the development of homo sapiens? We’re not that much different than the dudes that wiped out the Neanderthals. In a sense, we did stop evolving once we learned all that stuff in that we aren’t substantially different genetically. We’re the same species.

If you mean homo erectus or neanderthals evolving into homo sapiens, the answer is that they weren’t the dominant life form, and they faced situations that homo sapiens could handle better.
**

**
Sure. But that’s the difference between our brain and a lemur’s. Or probably just about any other one. It’s wired for complex problem solving. Other brains aren’t. The reason it’s wired that way is because of unique environmental pressures.

You could argue it, but you’d be wrong. Obviously lemurs didn’t need to, otherwise they would have. And while they could have benefitted from increased evolution, evolution doesn’t work that way. It does the bare minimum needed to survive. It’s not a conscious force, or a steady development. The ancestors of modern lemurs adapted to the evolutionary changes in different ways, maybe through fur coats or what have you. I don’t know that much about lemurs.
**

**
The intelligence gap existed before writing. The intelligence gap is what allows us to write and speak a language. You seem to believe that humans are more genetically evolved than they were 10,000 years ago, but that’s not the case. We’re just more socially evolved. That all came about through our greater problem solving ability, aka intelligence. The reason we have the greater intelligence is because our ancestors had the foundations for it, and the environment killed off those humans that didn’t have the greater intellect to deal with a changing environment over millions of years.

18

Just a small reminder: An awful lot of hominids that werent that far away from us went extinct. Any one of them might have originated a slightly different modern human. Environmental pressures helped determine what was more useful by just killing off the less sucessful.

19

Right if Homo erectus were around today (as in Harry Turtledove’s “A Different Flesh”), we wouldn’t see such a large gap between ourselves and our nearest relative. We’d be confronted with a species that makes complex tools, uses fire, has some sort of limited language, and could potentially produce sterile hybrids with humans. That species would be recognized as much much smarter than our next closest relative, the chimpanzee. But they would also clearly be less intelligent than humans, except for the developmentally disabled.

But H. erectus is now extinct, Homo habilis is extinct, Australopithecines are extinct. If bipedal apes still roamed the African savannas, we’d probably have a much better intuitive grasp of our evolutionary history.

The other thing to remember is that 20,000 years ago, humans were really just another species of large mammal. Sure, we had big brains and complex social interactions, but we weren’t that numerous, we made tools that were only slightly better than the Neandertal tool kit. We weren’t building space stations, or even growing plants for food and riding horses. And we are essentailly identical genetically to those people 20,000 years ago. There is no difference in intelligence between your average American factory worker and your average hunter gatherer. Both have an amazing set of skills that allow them to survive, but neither is any more innovative than the other. Don’t compare the chimpanzee’s technology to a Manhattan office worker, compare it to a Kalahari !Kung hunter-gatherer toolkit. Suddenly the differences don’t loom so large.

Building space ships and computers and nuclear bombs isn’t something that an individual human is capable of. Most humans never have a single inventive idea in their entire lives. And even if they do, the odds are that it will never be implemented. But if a few people DO have inventive ideas…and those ideas can be tested, and implemented, and recorded…then suddenly that slight increase in tool making capabilty snowballs into something remarkable.

But remember that evolution isn’t teleological. It doesn’t have a purpose. We didn’t evolve our big brains to enable us to work computers or build jet planes. We evolved our big brains to enable us to be more successful at living in a hunter-gatherer band. The computers were a side effect.

20

Exactly, thank you Lemur. And here I thought you were going to be offended by our use of your namesake.