Forum:How come there are still humans?

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This discussion was moved here from Talk:How come there are still monkeys?.

To my mind a far more interesting question is how come there is only one one species of Homo around thee days? I mean if being smart, standing upright and being able to make tools is such a great idea - how come all the other species of Homo didn't make it? I know that the popular answer is that we did them in, but I'm not so sure. You would have thought that some of them would have made it.

Which leads me to wonder if there is something "bad" about being too smart which leads to a dead end for some reason - but which we have avoided (so far).--BobSpring is sprung! 19:23, 28 May 2011 (UTC)

I am of the opinion that our special case derives from our ability to be functionally insane. No sane person would have come up with the need of a solar-centered (I mean, it's obvious that the sun goes around the Earth, the proof is RIGHT there each and every day!) planetary system...except to explain why the planets moved the way that they do.
Our ability to not accept the plain truth that is right in front of our eyes is at the heart of both our scientific acumen and our (collective) ability to make up the "real reasons" of why things are the way that they are, (religion).
Just as the mutation that provides immunity from malaria also causes sickle-cell disease, so too does our functional insanity both provide us with both the ability to be able to see behind the curtain of observable events (eventually) coming up with a correct interpretation and ascribing the path and the results to some gOD or another. 03:24, 29 May 2011 (UTC) C®ackeЯ
The puzzle is why, if we're so smart, so many humans would spend so much time and resources on finding out the minute details of the motions of those insignificant lights in the sky. What possible benefit would ever come to determining their positions down to a fraction of a degree? One might as well be interested in what color peas the plants in my garden will produce, or what will happen if I fly a kite in a thunderstorm. TomS TDotO (talk) 10:22, 29 May 2011 (UTC)
Chronology in this thread is all over the place. The other human species would have been extinct for a long term before sapiens sapiens worked out that Earth orbits the sun. WėąṣėḷőįďWeaselly.jpgMethinks it is a Weasel 10:41, 29 May 2011 (UTC)
Yes, the question is "why"? Many other species have multiple members of their groups. How come there is jut one surviving species of Homo? I'm obviously not suggesting there is any question of divine intervention here, it just seems odd to me that these is just one really intelligent species left. To put my question another way (and belabour the point) - if being smart is so cool why are we the only species that does to such a degree? Historically we're not the only smart species - how come the others didn't make it?--BobSpring is sprung! 15:07, 29 May 2011 (UTC)
Is there evidence that the other human species were "smart" (i.e. conscious) to the same extent as HSS? WēāŝēīōīďWeaselly.jpgMethinks it is a Weasel 15:22, 29 May 2011 (UTC)
The Neanderthals could probably have given us a run for the money. Homo habilis obviously used tools and so did Homo erectus. But that's part of my point - if being smart was soo cool why didn't it protect them and why didn't they simply keep getting smarter? Human evolution presumably wasn't a direct line but - like all other species - a bush. How come we are the only twig that remains? --BobSpring is sprung! 15:46, 29 May 2011 (UTC)
Note that HSS very nearly died out 70,000 years ago (the 2000-couple bottleneck). And that HSN then interbred with HSS, leaving the European gene pool slightly Neanderthal. We are remarkable but not unique, and having survived this long is mostly dumb fucking luck. Coming up with the agriculture hack led to quantum physics and Internet porn, but is there any reason coming up with and then doing agriculture would have been beyond HSN? We do not know - David Gerard (talk) 15:54, 29 May 2011 (UTC)
Since this happens to be strongly related to my thesis, I can give you some of the proposed hypotheses. Archaeologists and palaeoanthropologists have moved away from the view that they were simply outcompeted by Cro-Magnons over the past few years. In the 80's and 90's archaeologists believed almost universally that neanderthals lived in small groups and some believed that this made them more vulnerable than Cro-Magnon populations, who supposedly lived in larger groups. Consquently, they would have been more vulnerable to disease. More recently, however, cognitive archaeologists have started taking to Robin Dunbar's 'social brain hypothesis', which suggests that neanderthals lived in groups of approximately 144. Some statistical models have been proposed by archaeologists that support this idea, but the same is true of the small group hypothesis. Anyway, if you assume the SBH is true, it either means neanderthal groups, still being slightly smaller than Homo sapiens, failed to develop the same linguistic capacity to substitute for time spent on social grooming (see Aiello and Dunbar 1993 for full details) or that the two populations interbred (a hypothesis which was scornfully dismissed about three years ago but appears more likely than previously thought in light of new evidence. one of the appeals of the SBH is that it provides a convenient explanation for the origins of language, but the small group view can still be backed up with reference to Terrence Deacon's idea put forward in The Symbolic Species that encephalization led to a reorganisation of connections in the brain, in which case you can still cling to the death from disease hypothesis. I've personally become sympathetic to the interbreeding hypothesis, since I've read more than a view papers suggesting quite an advanced degree of symbolic communication in Homo neanderthalensis. On a side note, Homo floresiensis almost certainly died out due to their relative isolation. It's still a fairly hot topic of debate. --Danfly (talk) 16:49, 29 May 2011 (UTC)
Interesting but it's not really my point, which is why just this twig if being smart is so good. You suggest that we were "better" then the Neanderthals" because we were so socially able. David suggests simple good luck.
But in that case my point still stands. Being "smart" is apparently no great asset - or is not the asset we think it is. Incidentally, while we're on the subject of recent Homo species, I seem to recall the recent discovery of another recently deceased species in addition to floresiensis- I thought there was a third, but I can't find a link at the moment. Which still leaves me wondering why - if intelligence is so cool we are the only twig.--BobSpring is sprung! 18:01, 29 May 2011 (UTC)
Given HSN and HSS could apparently interbreed, "species" may (or may not) be pushing it. What I get from Danfly's comment is "yes, no, maybe, maybe not, this is terribly fascinating and a hot area of developing research which is absolutely fascinating." Which, of course it is. (And it's useful having an expert on hand.)
When talking about human intelligence, it helps to realise that, given the enormous metabolic energies consumed and difficulties in birth caused by our intelligence, that we are in fact the least intelligent possible creature that can do what we do and play chimpanzee politics as well as we can. Rather than "most intelligent", think of humans as "least unintelligent". Our intelligence is an extremely thin veneer on a chimp. Think of the joke about an ant sodomising an elephant and shouting "Take it, bitch!" - David Gerard (talk) 18:18, 29 May 2011 (UTC)
Yes, that's sort of what I'm getting at. We use a disproportionate amount of energy to run these big brains, they almost kill our mothers when we are born and even then we are born at such an early stage of development that we are operationally helpless for a couple of years. It's really not very efficient or very survival-friendly.--BobSpring is sprung! 18:32, 29 May 2011 (UTC)
But on the other hand, our extra intelligence makes us top predator in most ecosystems, and lets us manage food & energy supplies and form communities in ways other creatures couldn't. Overall it's a definite evolutionary advantage. WëäŝëïöïďWeaselly.jpgMethinks it is a Weasel 18:40, 29 May 2011 (UTC)
I agree with you that we tend to think intelligence in itself is a greater asset than it actually is when the goal is really about survival. Algae seems to do pretty well without it. I also think it's far too simplistic to look at intelligence as a single variable. There are different types of intelligence and I do indeed consider social intelligence to be one of the more useful (though I don not accept the social brain hypothesis as it stands), but what we know as social intelligence is only one way of programming co-operation among species. While I can't think of an example off hand, I'm certain some species that do not even have intelligence have developed equally successful co-operation strategies. Even looking at the wp article on sponges, their ancestors seem to have given up their neurons and. A lot of it, as stated earlier, will also boil down to chance. Survival strategies which would be useful in the long run may simply be abandoned because they do more harm than good in the short run. On the other hand, sometimes successful strategies are selected for and the external environment may change to encourage such developments even further. There is a theory stating that the warmth of the Eocene was beneficial to primate survival in this manner. Since you're on this site you've probably read The Selfish Gene, so I'm not really saying anything too different. On the whole, I agree with you. Intelligence is generally over-rated as a survival tool (though I still believe it played a critical role in the survival of our own species). It was something that happened to work for us and this may be due to no more than developing the right traits at the right time. This doesn't mean the characteristics we developed are in any way a better than those of many species that simply did not find the need for intelligence at all. I personally see intelligence itself as the product of various different survival mechanisms that were built up over time and kept because they were advantageous and came to be co-ordinated in a certain way, which in hindsight became an incredibly useful tool. It just stuck around because it worked for us. --Danfly (talk) 19:00, 29 May 2011 (UTC)

(Outdent.) OK that's fine and I agree. But I would tend to go even further. I suspect that there is something contra-survival in intelligence. Take human birth (mentioned previously). In all other animals it's a pretty straightforward procedure, or at least not a life-threatening one. Yet because of our big brains the foetus has to do some complex aerobics and the mother's life is put at risk during each birth. The majority of births are single and not multiple. And then our parents need to take care of us for ages which tends to reduce their reproductive capacity. Today we can use our intelligence to make spaceships or look for dark matter or whatever but it must have been really costly when life was nasty brutish and short.

Which brings me to another mater. Why the hell do we have so much intelligence? We evolved on the African savannah to chase antelopes and avoid being killed. But lots of animals do that (well lots of predators). We are basically the same species. Why then do we have the intelligence to send men to the moon? Why did we need so much intelligence? --BobSpring is sprung! 19:38, 29 May 2011 (UTC)

One strong current hypothesis is that our brains are an evolutionary runaway - a peacock's tail - from doing chimpanzee politics. That is, coming up with workable solutions to the "I know you know I know you know ..." problem is so ridiculously difficult that general intelligence turns out to be an efficacious solution. Like many evolutionary runaways, this one nearly killed the species afflicted by it; but general intelligence, even in the meagre quantities our pissy little monkey brains can summon forth, just happened to turn out to have unexpected useful applications, like solving the food and shelter problems, inventing quantum physics and Internet porn and going to the moon. All of which are mere byproducts of the very hardest problem we know of: how to convince the other chimp to give you the fruit - David Gerard (talk) 20:53, 29 May 2011 (UTC)
I read recently (within the last 14 days, I think) that the ancestral brain was supersized to cope with increase in the sense of smell & when we(sic) didn't need said sense as much, it was adapted to make us "intelligent". Other ideas are that it was required to use language or to keep track of social relationship (although meercats seem pretty good at that) Pippa (talk) 21:20, 29 May 2011 (UTC)


The encephalization problem is discussed (though briefly) in one of Dunbar's papers

Large brains will evolve only when the selection factor in their favor is sufficient to overcome the steep cost gradient. Developmental constraints are undoubtedly important, but rather than being causal their role is that of a constraint that must be overcome if larger brains are to evolve..

Dunbar 1993

To put it simply, the benefits just outweigh the costs in his view. More specifically, the complex social systems that encephalization made possible was the real advantage (primarily due to the relative enlargement of the neocortex). Even taking Deacon's view that encephalization merely led to a 'rewiring' the same case can still be made, since the language we have evolved because of our large brains is undeniably incredibly useful. There is also a belief commonly held amongst archaeologists that the working of stone tools was instrumental in the development early of our intelligence. The book is a bit dated now, but Steven Mithen's Prehistory of the Mind has this to say:

We must conclude, therefore, on a rather equivocal note. On the one hand the making of Oldowan stone tools requires an understanding of fracture dynamics that appears beyond the capacity of the chimpanzee mind. On the other hand the stasis in Oldowan technology, the absence of imposed form and the preference for the easier raw materials prevent us attributing Homo habilis with a technical intelligence beyond a few micro-domains

. He suggests that the early stone tool makers were only marginally smarter than modern chimpanzees (and chimps seem to be catching up). They supposedly utilized these stone tools to cleave meat from carcasses (Our ancestors were already omnivores by the time of H. habilis). You've no doubt come across the hypothesis that our brain size was facilitated by the energy provided by red meat before. Aiello and Leslie have their own more specific view that for the body to be reduced to a stable metabolic rate, the gut became smaller in order to facilitate the enlargement of the brain. Presumably, once we reached the stage where encephalization had proven to be a beneficial development all the rest followed. as for why we have so much intelligence, I would attribute most of it to our highly complex language. To me, looking for dark matter and building spaceships owe more to the social evolution facilitated by language than a specific selection process. At the end of the day though, these are all stabs in the dark. I no more know the reasons for humans having so much intelligence than anyone else. I've just picked a few guesses out an ever increasing pile of guesswork that offer potential answers. The problem is, it's pretty hard to collect evidence for all of this. When it comes to prehistory, all we really do is say 'Oh look, I see some proxies for intelligence here, unlike that previous site. What can I infer from this and what factors may account for the difference?'.

What David mentioned (i.e. 'theory of mind' and 'orders of intentionality' to use the technical jargon) is another contributing factor I failed to mention while writing the above (there was an EC) However, I think it is implied by the complex social systems I mentioned. --Danfly (talk) 21:23, 29 May 2011 (UTC)

Shall we yank this thread over to the Forum what with it not really being about the article here? WéáśéĺóíďWeaselly.jpgMethinks it is a Weasel 21:31, 29 May 2011 (UTC)
Yes. I was thinking about that myself. --Danfly (talk) 21:46, 29 May 2011 (UTC)