In my last rant I tried to convey the idea that, when it comes to explaining the difference between humans and chimpanzees - to me the ultimate question - we can rank various ideas on a ladder (a kind of 'scala natura') in terms of how satisfying they are with, most satisfyingly of all, the "God did it" explanation right at the bottom.
I suggested, rather cheekily I thought, that random forces - although certainly involved to a huge extent - would appear only one up from God on the next rung of the ladder, closely followed by "Evo-Devo" (pro neoteny) arguments and then ones to do with sexual selection. Bravely holding the adaptationist banner up high, I claimed that only adaptation can offer truly satisfying explanations in Biology and therefore adaptationist explanations for the differences between human and chimpanzees are really the most interesting and important ones.
Here though, we get into potentially sticky ground because there is a danger of following in the footsteps of Rudyard Kipling and building "just so" stories. All sorts of nice-sounding 'explanations' have been put forward, for example, to explain the evolution of hominin bipedalism. (Bipedalism that evolved on the evolutionary lineage leading to man.) I've been studying this subject for several years now and I think there are probably at least 33 distinct ideas that have been published to explain this difference. Anything from "it was to reduce our body's profile in the mid-day equatorial sun" to "it was to enhance penile display." I won't list them all out but anyone who knows anything about anthropology will be familiar with at least six or seven of them. I say there are about 30 but, in truth, they can be categorised into several broad groups. Among the more sensible ones are those that suggesting carrying things was the key driver, those that food procurement was the most important reason for upright posture and others that it was simply more energy efficient to move on two legs than four.
Now if you look at these ideas in detail, and I have, what tends to strike you is that they all seem to make sense at some level but, equally clearly, they all seem to have a few problems too. None of them are wholly satisfying but all of them are somewhat satisfying. Frustrating, isn't it? Of course, faced with such a dilemma it is easy to think maybe they were all involved to some degree. It is certainly a common sense position that must be closer to the truth than the unlikely possibility that, actually, one of the proponents of these models got it completely right and everyone else got it completely wrong.
So what is the mainstream view on this today? What do university level students get taught about it? Surely, after 150 years since Darwin we should have something solid and sensible to say on the matter, shouldn't we? Well this is basically what I returned to academia to find out and I have to say I have been rather disappointed with what I discovered, to say the least. At University College London (UCL) and then at the University of Western Australia (UWA) and, I suspect, also at the vast majority of universities in the world where evolution is taught as fact, rather than fiction, what seems to be taught is basically the savannah theory.
The what? ... The savannah theory.
Now before people start objecting that there never was a savannah theory, that it was actually a straw man invented purely for the purpose of knocking it down (yes, this view even reached the respectable pages of the Journal of Human Evolution in 1997), let's be clear - practically every text book written on human evolution in the past 75 years aludes to, or explicitly cites, the idea that climate change in Africa - and by that we mean a change to increased aridity - was the thing that did it. It was the resulting change in habitat from closed forest to open woodland and grassland, sometimes called "parkland" but more often called "savannah", that was responsible for the process of 'homininisation'.
Most of the 30-odd explanations of bipedal origins assume this quite openly although there are some clear exceptions. In fact just this year (2007) a paper was published in the journal Science with front page prominence, by Robin Crompton's very well respected team of researches in Liverpool, espousing one such view. Their model, if it can be caled that, is that orang-utan-like, tree-wobbling, upright posture whilst reaching for food in the thinner branches of trees was a likely precursive form of locomotion not only for hominins but actually for all the great apes.
Now it seems to me that this is an explanation that can be equally accurately labelled as "obvious" and "silly", at the same time. It's obvious in the sense that, of course, the ancestor of all the great apes was almost certainly arboreal and would have, to a large extent, had to feed from thin branches. Whilst doing so a precarious form of upright posture is likely to have been held for a few minutes and this upright orientation of the body, encouraged too by vertical climbing in relatively large mammals, would have orientated the body in the direction of greater bipedalism. I do not think it is silly, by the way, that the authors suggest that this form of 'arboreal proto-bipedalism' was also likely to have been the ancestral condition of the other great apes too. Since the discovery of Orrorin in 2000, I've been persuaded that the fossil evidence suggests that bipedalism was actually so old it may well pre-date the last common ancestor (LCA) of the human and the chimp, and maybe also the gorilla and the orang-utan too. It strikes me as a classic case of anthropocentrism that we are tempted to imagine the LCA as very similar to a chimpanzee. It's us that have done all the evolving. The stupid chimps have basically stayed the same. I doubt it. It seems much more likely that the precursor of bipedalism and knuckle-walking (let's face it, a rather off form of quadrupedalsim) was some kind of semi-arboreal bipedalism.
No, what I think is silly about the Science paper is that it is very thin on the ground when it comes to giving good reasons as to why only one lineage from that ancestral quasi-bipedal great ape became obligate bipeds, whilst all the others reverted to quadrupedalissm. Well no reason, that is, apart from the good old savannah theory. What? Didn't I say that this was an idea that didn't posit bipedal origins in a savannah context? Yes I did. And, to be fair, they didn't. They posited bipedal origins to have begun in a forested environment. It's just that once it had begun, it was the ones that left the trees, they argue, that somehow were left standing on two legs, whereas the ones that stayed in the woodland became quadrupedal. Now that's what I think is silly.
I could ramble on all night about other ideas of bipedal origins and how I think they're silly too but I won't. Actually, I find some of them rather compelling. I actually quite like the energy efficiency model of Rodman & McHenry fame, for example. It does make sense that moving on just two legs, especially when they're long and able to lock into a straight, inverted-pendulum gait, has to be more efficient than moving on four, relativly short, bendy legs. When doing so, you're using half as many limbs but mainly you're using the kinetic energy of falling forward to power most of your propulsion. Muscle power is really only used to fine tune the positioning of the limbs as they swing into position for the next step.
It makes sense although there are problems: It's clear that we move more efficiently than chimpanzees do today, but only because our anatomy is manifestly adapted to efficient walking and only when that locomotion is conducted on certain special substrates.
So here's problem one: All the evidence which shows humans being more efficient at locomotion than chimpanzees have been conducted on that most special substrate - remarkably rare in the natural world - the treadmill. It strikes me that this is a bit of a loaded dice. Humans naturally find walking on very flat, firm, relatively vegetation free substrates not only easy but quite appealing. I have often wondered just how appealing walking on a treadmill is to a chimpanzee. No matter how well the animal is desensitised to doing so, it must be quite unnatural at best and, at worst, quite terrifying. Experiments have shown that humans are much less efficient when moving through less perfect substrates. I have myself done experiments with douglas bags which show that even walking through long grass adds about 20% to the cost of walking as compared to that on concrete. It makes me think that when it comees to moving through bushland or especially dense forest, the supposed energetic advantage of bipedalism quickly disappears.
The second problem is that there was probably an energetic 'rubicon' to cross for an early hominin biped not quite adapted to bipedalissm. How or why was bipedalism practised even before the anatomical adaptatations which make it efficient evolve? A recent paper gave good evidence that perhaps, by chance, some chimps started exhibiting a more upright gait and because they got some slight energetic benefit from that it became selectd for. A chain of events started at the end of which some populations just happenned to move more bipedally than others. Now this is possible of course, perhaps it is even likely, but, as you will have gathered already, I just don't find that sort of explanation very satisfying. Why didn't all chimpmanzillas (my label for the LCA of chimp, man and gorilla) encounter similar scenarios? Maybe it is the explanation we will end up adopting but first, perhaps we should first try to find a better one.
I think there is a more satisfying one and, you will not be surprised to read, it is based on the crazy, outrageous idea that our ancestors actually spent a significant amount of time (but note not all that much time) wading through shallow water. The thing about shallow water and apes is this: they are far, far more likely to move bipedally there than on dry land. And I mean "move". In trees or on the edges of bushes, whilst doing the behaviour "postural feeding", apes do not do much moving at all, they do a lot of standing and reaching and grabbing and eating. When they do move they almost always move with support, by holding onto a handy branch. Only in water are apes compelled to move bipedally and almost always it is without support. Clearly the actual depth of water is an important factor to consider. In very shallow water, say a few centimetres only, there is obviously no such compulsion. In fact, as has been reported in bonobos, if they were foraging food in the water, perhaps on the underside of floating leaves, they are actually compelled to move quadrupedally. But, equally clearly, the deeper the water gets the more likely they are to switch to bipedalism. In waist deep water a chimp simply has no choice and all the evidence shows that they do, indeed, move bipedally there.
Now, that to me is as satisfying an explanation as you can get: An ancestral scenario where if our ancestor moved quadrupedally it would die but if it moved bipedally it would live. Can we think of any other scenario where bipedalism would confer such a clear cut advantage? No. Can we think of any other taxa on the planet that exhibit this peculiar shift in locomotor pattern in this scenario? No. (Do dogs, horses, pigs, cats etc switch from quadrupedalism to bipedalism in shallow water? No.)
It is almost ceratinly not the only reason our lineage adapted bipedalism but I think it must be a big part of the reason. In the next rant, I'll go on about why, if it's such a good idea, it's not already in the mainstream and what must happen before it will get there.
All the best
Algis Kuliukas
Thursday, November 15, 2007
Saturday, November 3, 2007
Chimpanzee-Human Differences - Problems
Ok, this is what it's all about. If you take a look at the apes - the gibbons, the orang-utan, the gorilla, the chimpanzee and the bonobo. Oh did I miss one? Yes - and us Homo sapiens, and compare them, it's clear that one species stands out like a sore thumb and that's us.
There is a clear danger here of bias. After all, it's us doing the comparing. I imagine that if you have an identical twin it might get a little irritating to be constantly confused for someone else all the time. To you, it's obvious that you're very, very different from that other person that you keep being mistakenly referred to. But to everyone else, it's clearly not so obvious. There's also a danger of anthropocentrism because we humans have a long history of deluding ourselves that the whole universe was put here just for us.
But, putting this bias aside for a moment, when the DNA of the apes, or any molecule for that matter, is analysed and compared - humans consistantly turn out to have structures closer to chimpanzees than to any other ape and, more importantly, the same is true of the chimpanzee. We are closer to them than the gorilla, the orang-utan and, of course, the gibbons. Exactly the same is true of bonobos by the way. They are exactly as closely related to us as the chimpanzees - in the same way as you are exactly as closely related to your aunt Bethany as your sister.
Anyway, this is the main point: We are the chimps' closest relation in he world and yet, even to a Martian, they have many more features in common with gorillas and orang utans than they do with us and this observation is in need of an explanation.
Now, if you've been unfortunate enough to have been brain-washed as a child into believing in God, or naive enough to have come to this conclusion yourself, the "explanation" is really simple: 'God' made us that way. He (God was male, of course) created the entire universe just for our benefit. He created the world about 6,000 years ago and, just to keep us company or perhaps just to make us feel superior to everything else on the planet, he created lots of other creatures too. Seen through this fog of self-delusion, it makes perfect sense that we are clearly very different from the chimpanzees. After all, we have a soul and are destined to an eternal life in heaven as long as you've followed all the silly rules laid down in the scriptures and never done anything really bad like dare to deny that there is any stupid god - in which case you're destined to an eternal burning hell. (Great justice that!) Chimps don't have souls, they're animals. God clearly doesn't give a shit about them.
Ok, enough sillines. Let's for a moment assume that you're not a creationist, or suffering from any other form of madness that can be classed as religion. Let's assume you're a rational person who needs a rational explanation for the difference between humans and chimpanzees.
Now it seems to me that there is a level of "explanation" that is rational but hardly more satisfying than the "god did it" story. It goes like this: Evolution is pretty random. Things happen just by chance alone, usually. You have random mutations, random genetic drift and random extinction events. That's a lot of random effects for a long period of time. So, according to an extreme form of this argument, humans are different from chimps because they are different from chimps. One lineage of apes just started going off down a peculiar evolutionary pathway that increasingly diverged from their cousins for no better reason than it "just happenned". Maybe a group of apes found themselves isolated in a small group and, by chance, they happenned to be slightly more likely to move on two legs. Their isolation led to inbreeding and gehes that help bipedalissm became fixed and, hey presto, you have a group of hominids. Iterate this process a few more times and, eventually, you'd get the genus Homo.
Now I don't know anyone that actually espouses this view exactly, but some do come close. My intellectual hero, Richard Dawkins, comes pretty close actually, when he suggests that bipedal origins may have just been a kind of cultural meme that "just happenned". I'm disappointed that he thinks that is enough of an explanation for the ape-human divergence. I think we can do better.
I should point out here that I am not trying to suggest, in the least, that random forces were not at play during human evolution, or even that they weren't a very big, or even the biggest, part. Clearly they were very important. In this rant, I'm portraying creationism at the bottom of a ladder of explanations and certain types of adaptation at the top but please don't think that the ladder is any kind of ranking of likelihood. To most rational minds, the idea that God created humans is almost certainly false and by saying "almost certainly" we mean it much closer to 'certainly' than we can meaningfully convey in the English language. The only reason we don't just say it is "certainly" false is because we can hardly be certain of anything outside of the world of mathematics. But it's just being pedantic. Really, I'm quite certain that there's no God and I suspect most rational people are too. I think it equally clear that random forces certainly were involved in evolution, particularly when we think of the molecular basis of life. Mutations are the fuel which provides the variation on which selection can work and mutations are, by definition, random. You also have random drift and random extinctions not to mention a host of other random effects that can certainly cause changes to the course of any lineage.
No, my point in placing random forces just one notch above creationism is that it is barely more satisfying. When Stephen J Gould suggested that if we re-wound the tape of life from the beginning it would almost certainly come up with a very differeent situation today, he was making a very valid point. Clearly things would be different. Many aspects of life on the planet we take for granted might not be reproduced. If "that meteor" had not hit earth 65 million years ago (or whatever event caused the extinction of the dinosaurs) then it is very likely that mammals would not have reached their dominant position and apes might not have had the chance to evolve into humans. This much is true and rather obvious. However, just saying that we're here because of some stupendous lottery or, more accurately, a billion stupedous lotteries, doesn't satisfy my curiosity much better than the "God did it" explanation. As I said... I think we can do better but, at the same time, as we are trying to do better we must remember that, underneath the layers of "explanation" that we can come up with is a very massive, fluid, random foundation of pure chance.
Anyway, to get back to the plot, another notch away from unsatisfactory explanations towards a really satisfying ones can be achieved when you add to 'pure randomness' the real impact of embryological development: The "Evo Devo" factor. On top of random forces, now we also need to consider, constraints that arise out of development. It is difficult to see how this kind of effect might have had an impact early in ape-human divergence but it clearly had a big impact later on. Human infants, with their large brains, are clearly much more problematic, compared to chimpanzees, when it comes to giving birth. Signficant alterations to the timing of the phases of pregancy and birthing have resulted from this evolutionary change. In a nutshell, humans are born 'early' in developmental terms, making our infants much more vulnerable and dependent on their mothers for the first few years. This dependence on parents has clearly had a big impact in our evolution and might well help explain many ape-human differences like the extra involvement of fathers in raising children and the increased importance of play. The trend towards altriciality (increased dependence on the parents in early life) is a clear one in the human lineage. Our fish ancestors didn't give a hoot about their offspring. Shed a billion eggs and sperm and the sheer numbers involved will increase the tiny probability of survival sufficiently to make it viable. Land-based reptilians were a little more caring, looking after the eggs before they're hatched and for a while afterwards. Our mammalian ancestors invested much more time and resource in their offspring and primates follwed the trend even more. Of all the primates, the great apes look after their young more than any other and we humans are the mother of all mothers. I do not think it is a coincidence that today, in the early part of the 21st century, those of us privileged to be living in better educated societies are expected to invest the highest ever amounts of time and money into our children and feel guilty when we do not quite live up to expectations.
On the next rung up, in my view, is the additional factor of sexual selection. Any species that reproduces through sexual selection is potentially subject to sexual selection. In birds, it's most often the males that exhibit amazing displays in order to attract the attention of the females. We all know examples of beautiful birds of paradise and the often cited peacock's tail as clear examples of the phenomenon. A particular feature evolves, as if out of control, in almost random directions in order to invoke attention in an opposite sex that is increasingly unimpressed with mediocrity. Mammals don't often exhibit such extreme examples of sexual selection but, generally speaking, as females are the precious ones, the limiting factor in terms of reproduction, it is males that compete for privileged access to them. In many species, especially social species, the situation that seems to evolve is one based on a single male's dominance. The alpha male and his harem is a rather common situation in social primates and gorillas and chimpanzees, two of our closest relatives, have socio-sexual systems that are pretty much based on this.
In such systems, males compete agressively with each other and what results is clear sexual dimorphism. Gorilla and orang-utan males are much bigger than females and this is no coincidence. The same is true of chimpanzees, but to a lesser degree. Chimp society is clearly dominated by males although it is usually a kind of political coalition of brothers in arms, rather than a single alpha male, that controls things. Human males are also bigger than females although, again, to an even lesser extent which seems to indicate that male domination of socio-sexual systems was almost certainly a key aspect at some point in our evolutionary history. Who knows, the need for a good old reliable alpha male somewhere nearby might well help explain the mass delusional tendancy for human societies, wherever they may be, to invent imaginary gods to protect them from evil and offer reassurances in their confused lives.
However there is a spanner in the works: Remember the bonobos? They are equally closely related to us as are the chimpanzees and yet they do not have male dominated
socio-sexual systems. Their societies are dominated by sisterhoods and motherhoods. It's the alpha-female that rules the nest here. Males are basically ranked according to who their mum is. Whereas chimpanzees only have sex for producing children, bonobos have sex all the time apparently to ease tensions between the group.
How can we explain this difference? Chimpanzees and bonobos diverged perhaps as little as 2-3 million years ago - not all that long in evolutionary terms. It seems likely to me that the difference is explained mainly by food availability. Basically the important gender is the female. As long as she has enough food to live and raise her infants in a safe environment the species will prosper. All she needs from males is a tiny blob of sperm every few years and she is happy enough. The males, of course, are more than willing to provide that. Now if you compare the ecology of chimps and bonobos, two major differences come to light: Firstly chimp habitats may overlap with that of gorillas. With all great ape populations diminsihing today it's not easy to see examples of the two species sharing a given habitat but it is likely that in the paast 3 million years or so this was indeed a major phenomenon. Competition with gorillas would have made some food sources harder to come by and required greater foraging distances to procure them. Bonobos live inside the ring of the great Congo river effectively isoltaing them from both chimps and gorillas. This habitat is amongst the richest in the world if you eat fruit and vegetation, like bonobos, so life must be relatively easy for them.
Again we see a similar trend in humans here. In times of hardship, wars often happen and when they do, male dominated societies seem to result. In times of plenty and peace, women seem to dominate more. Perhaps it is a coincience but there has also been a clear trend towards greater sexual permissiveness as economies have boomed and gaps between wars have increased.
So, getting back to sexual selection, what do we see in humans that might help us explain the differences between ourslves and the great apes? Well, this is often the main explanation invoked for body hair loss and increased fat. Women have less body hair than men and they are fatter. Their body fat is generally deposited in a manner that is indicative of sexual maturity and is obviously very appealing to men. Clearly some sexual selection has been responsible for this sexual dimorphism. At the risk of venturing onto the thin ice of political incorrectnesss, most men fancy women with smooth skin and a shapely body, and most women fancy men that do not have breastss but have manly, muscular torsos with some semblance of body hair to indicate that they are really men. All this is satisfying to some degree but it begs the question: how or why did that chain of events start in the first place?
When it comes to the peacock's tail, there's a rather elegant explanation which has been published called the "costly signalling hypothesis." The idea is that the peacock is signalling to the feamles "look at me! I'm so healthy I can afford to grow and maintain this impecable array of ridiculously large feathers". An analogy might be a rich man buying a flash sports car or an expensive watch to impress the chicks. The point iis: it's a signal that is hard to fake, it is costly. The female is bound to be impressed because to have such a visible trait is potentially dangerous to the male (it might attract a predator) and is costly to them (they have to eat extra food to 'pay' for such things.) Perhaps this kind of idea might be adapted to human sexual differences?
It's hard to see how it could be at work in women. After all, they are the resource in demand. Males make billions of sperm every day that can literally be thrown away. Females do not need any costly signalling to advertise their worth. Males know that already. So what about male adornments? Perhaps there is some way that hairy chests and beards and deep voices could be costly signals? We'll see.
But when it comes to those key ape-human differences nakedess and increased fat, although one can imagine that sexual selection was involved in it's maintainence, it's harder to see how it might have begun in the first place. Why would women suddenly become sexy to men, when they had smooth skin and not, instead, fancy "a bit of rough". It's certainly not a trait a chimpanzee or the sex-mad bonobos seem to find attractive. The same with those lovely curves. Perhaps there are better explanations ahead.
Another notch up from sexual selection is the really interesting and ultimately satisfying area of natural selection: adaptation. This is where Darwinism really makes most sense. What kinds of environment would we expect the features that make us different from apes to have some significant adaptive value?
This question has been the main focus of paleoanthropologists for over 150 years and for most of that time most seemed to have assumed that the environment in question was, for want of a better term... savannah.
Now this is where we get to the interesting part. But I'll cover that in my next posting. And, of course, that's where I hope to show that waterside explanations are the only ones that are ultimately most satisfying, four notches up from creationism, three from random drift, two from sexual selection and one about adaptive explanations of open habitat or fudgdey notions of "savannah-woodland-mosaics" (whatever they are).
Algis Kuliukas
There is a clear danger here of bias. After all, it's us doing the comparing. I imagine that if you have an identical twin it might get a little irritating to be constantly confused for someone else all the time. To you, it's obvious that you're very, very different from that other person that you keep being mistakenly referred to. But to everyone else, it's clearly not so obvious. There's also a danger of anthropocentrism because we humans have a long history of deluding ourselves that the whole universe was put here just for us.
But, putting this bias aside for a moment, when the DNA of the apes, or any molecule for that matter, is analysed and compared - humans consistantly turn out to have structures closer to chimpanzees than to any other ape and, more importantly, the same is true of the chimpanzee. We are closer to them than the gorilla, the orang-utan and, of course, the gibbons. Exactly the same is true of bonobos by the way. They are exactly as closely related to us as the chimpanzees - in the same way as you are exactly as closely related to your aunt Bethany as your sister.
Anyway, this is the main point: We are the chimps' closest relation in he world and yet, even to a Martian, they have many more features in common with gorillas and orang utans than they do with us and this observation is in need of an explanation.
Now, if you've been unfortunate enough to have been brain-washed as a child into believing in God, or naive enough to have come to this conclusion yourself, the "explanation" is really simple: 'God' made us that way. He (God was male, of course) created the entire universe just for our benefit. He created the world about 6,000 years ago and, just to keep us company or perhaps just to make us feel superior to everything else on the planet, he created lots of other creatures too. Seen through this fog of self-delusion, it makes perfect sense that we are clearly very different from the chimpanzees. After all, we have a soul and are destined to an eternal life in heaven as long as you've followed all the silly rules laid down in the scriptures and never done anything really bad like dare to deny that there is any stupid god - in which case you're destined to an eternal burning hell. (Great justice that!) Chimps don't have souls, they're animals. God clearly doesn't give a shit about them.
Ok, enough sillines. Let's for a moment assume that you're not a creationist, or suffering from any other form of madness that can be classed as religion. Let's assume you're a rational person who needs a rational explanation for the difference between humans and chimpanzees.
Now it seems to me that there is a level of "explanation" that is rational but hardly more satisfying than the "god did it" story. It goes like this: Evolution is pretty random. Things happen just by chance alone, usually. You have random mutations, random genetic drift and random extinction events. That's a lot of random effects for a long period of time. So, according to an extreme form of this argument, humans are different from chimps because they are different from chimps. One lineage of apes just started going off down a peculiar evolutionary pathway that increasingly diverged from their cousins for no better reason than it "just happenned". Maybe a group of apes found themselves isolated in a small group and, by chance, they happenned to be slightly more likely to move on two legs. Their isolation led to inbreeding and gehes that help bipedalissm became fixed and, hey presto, you have a group of hominids. Iterate this process a few more times and, eventually, you'd get the genus Homo.
Now I don't know anyone that actually espouses this view exactly, but some do come close. My intellectual hero, Richard Dawkins, comes pretty close actually, when he suggests that bipedal origins may have just been a kind of cultural meme that "just happenned". I'm disappointed that he thinks that is enough of an explanation for the ape-human divergence. I think we can do better.
I should point out here that I am not trying to suggest, in the least, that random forces were not at play during human evolution, or even that they weren't a very big, or even the biggest, part. Clearly they were very important. In this rant, I'm portraying creationism at the bottom of a ladder of explanations and certain types of adaptation at the top but please don't think that the ladder is any kind of ranking of likelihood. To most rational minds, the idea that God created humans is almost certainly false and by saying "almost certainly" we mean it much closer to 'certainly' than we can meaningfully convey in the English language. The only reason we don't just say it is "certainly" false is because we can hardly be certain of anything outside of the world of mathematics. But it's just being pedantic. Really, I'm quite certain that there's no God and I suspect most rational people are too. I think it equally clear that random forces certainly were involved in evolution, particularly when we think of the molecular basis of life. Mutations are the fuel which provides the variation on which selection can work and mutations are, by definition, random. You also have random drift and random extinctions not to mention a host of other random effects that can certainly cause changes to the course of any lineage.
No, my point in placing random forces just one notch above creationism is that it is barely more satisfying. When Stephen J Gould suggested that if we re-wound the tape of life from the beginning it would almost certainly come up with a very differeent situation today, he was making a very valid point. Clearly things would be different. Many aspects of life on the planet we take for granted might not be reproduced. If "that meteor" had not hit earth 65 million years ago (or whatever event caused the extinction of the dinosaurs) then it is very likely that mammals would not have reached their dominant position and apes might not have had the chance to evolve into humans. This much is true and rather obvious. However, just saying that we're here because of some stupendous lottery or, more accurately, a billion stupedous lotteries, doesn't satisfy my curiosity much better than the "God did it" explanation. As I said... I think we can do better but, at the same time, as we are trying to do better we must remember that, underneath the layers of "explanation" that we can come up with is a very massive, fluid, random foundation of pure chance.
Anyway, to get back to the plot, another notch away from unsatisfactory explanations towards a really satisfying ones can be achieved when you add to 'pure randomness' the real impact of embryological development: The "Evo Devo" factor. On top of random forces, now we also need to consider, constraints that arise out of development. It is difficult to see how this kind of effect might have had an impact early in ape-human divergence but it clearly had a big impact later on. Human infants, with their large brains, are clearly much more problematic, compared to chimpanzees, when it comes to giving birth. Signficant alterations to the timing of the phases of pregancy and birthing have resulted from this evolutionary change. In a nutshell, humans are born 'early' in developmental terms, making our infants much more vulnerable and dependent on their mothers for the first few years. This dependence on parents has clearly had a big impact in our evolution and might well help explain many ape-human differences like the extra involvement of fathers in raising children and the increased importance of play. The trend towards altriciality (increased dependence on the parents in early life) is a clear one in the human lineage. Our fish ancestors didn't give a hoot about their offspring. Shed a billion eggs and sperm and the sheer numbers involved will increase the tiny probability of survival sufficiently to make it viable. Land-based reptilians were a little more caring, looking after the eggs before they're hatched and for a while afterwards. Our mammalian ancestors invested much more time and resource in their offspring and primates follwed the trend even more. Of all the primates, the great apes look after their young more than any other and we humans are the mother of all mothers. I do not think it is a coincidence that today, in the early part of the 21st century, those of us privileged to be living in better educated societies are expected to invest the highest ever amounts of time and money into our children and feel guilty when we do not quite live up to expectations.
On the next rung up, in my view, is the additional factor of sexual selection. Any species that reproduces through sexual selection is potentially subject to sexual selection. In birds, it's most often the males that exhibit amazing displays in order to attract the attention of the females. We all know examples of beautiful birds of paradise and the often cited peacock's tail as clear examples of the phenomenon. A particular feature evolves, as if out of control, in almost random directions in order to invoke attention in an opposite sex that is increasingly unimpressed with mediocrity. Mammals don't often exhibit such extreme examples of sexual selection but, generally speaking, as females are the precious ones, the limiting factor in terms of reproduction, it is males that compete for privileged access to them. In many species, especially social species, the situation that seems to evolve is one based on a single male's dominance. The alpha male and his harem is a rather common situation in social primates and gorillas and chimpanzees, two of our closest relatives, have socio-sexual systems that are pretty much based on this.
In such systems, males compete agressively with each other and what results is clear sexual dimorphism. Gorilla and orang-utan males are much bigger than females and this is no coincidence. The same is true of chimpanzees, but to a lesser degree. Chimp society is clearly dominated by males although it is usually a kind of political coalition of brothers in arms, rather than a single alpha male, that controls things. Human males are also bigger than females although, again, to an even lesser extent which seems to indicate that male domination of socio-sexual systems was almost certainly a key aspect at some point in our evolutionary history. Who knows, the need for a good old reliable alpha male somewhere nearby might well help explain the mass delusional tendancy for human societies, wherever they may be, to invent imaginary gods to protect them from evil and offer reassurances in their confused lives.
However there is a spanner in the works: Remember the bonobos? They are equally closely related to us as are the chimpanzees and yet they do not have male dominated
socio-sexual systems. Their societies are dominated by sisterhoods and motherhoods. It's the alpha-female that rules the nest here. Males are basically ranked according to who their mum is. Whereas chimpanzees only have sex for producing children, bonobos have sex all the time apparently to ease tensions between the group.
How can we explain this difference? Chimpanzees and bonobos diverged perhaps as little as 2-3 million years ago - not all that long in evolutionary terms. It seems likely to me that the difference is explained mainly by food availability. Basically the important gender is the female. As long as she has enough food to live and raise her infants in a safe environment the species will prosper. All she needs from males is a tiny blob of sperm every few years and she is happy enough. The males, of course, are more than willing to provide that. Now if you compare the ecology of chimps and bonobos, two major differences come to light: Firstly chimp habitats may overlap with that of gorillas. With all great ape populations diminsihing today it's not easy to see examples of the two species sharing a given habitat but it is likely that in the paast 3 million years or so this was indeed a major phenomenon. Competition with gorillas would have made some food sources harder to come by and required greater foraging distances to procure them. Bonobos live inside the ring of the great Congo river effectively isoltaing them from both chimps and gorillas. This habitat is amongst the richest in the world if you eat fruit and vegetation, like bonobos, so life must be relatively easy for them.
Again we see a similar trend in humans here. In times of hardship, wars often happen and when they do, male dominated societies seem to result. In times of plenty and peace, women seem to dominate more. Perhaps it is a coincience but there has also been a clear trend towards greater sexual permissiveness as economies have boomed and gaps between wars have increased.
So, getting back to sexual selection, what do we see in humans that might help us explain the differences between ourslves and the great apes? Well, this is often the main explanation invoked for body hair loss and increased fat. Women have less body hair than men and they are fatter. Their body fat is generally deposited in a manner that is indicative of sexual maturity and is obviously very appealing to men. Clearly some sexual selection has been responsible for this sexual dimorphism. At the risk of venturing onto the thin ice of political incorrectnesss, most men fancy women with smooth skin and a shapely body, and most women fancy men that do not have breastss but have manly, muscular torsos with some semblance of body hair to indicate that they are really men. All this is satisfying to some degree but it begs the question: how or why did that chain of events start in the first place?
When it comes to the peacock's tail, there's a rather elegant explanation which has been published called the "costly signalling hypothesis." The idea is that the peacock is signalling to the feamles "look at me! I'm so healthy I can afford to grow and maintain this impecable array of ridiculously large feathers". An analogy might be a rich man buying a flash sports car or an expensive watch to impress the chicks. The point iis: it's a signal that is hard to fake, it is costly. The female is bound to be impressed because to have such a visible trait is potentially dangerous to the male (it might attract a predator) and is costly to them (they have to eat extra food to 'pay' for such things.) Perhaps this kind of idea might be adapted to human sexual differences?
It's hard to see how it could be at work in women. After all, they are the resource in demand. Males make billions of sperm every day that can literally be thrown away. Females do not need any costly signalling to advertise their worth. Males know that already. So what about male adornments? Perhaps there is some way that hairy chests and beards and deep voices could be costly signals? We'll see.
But when it comes to those key ape-human differences nakedess and increased fat, although one can imagine that sexual selection was involved in it's maintainence, it's harder to see how it might have begun in the first place. Why would women suddenly become sexy to men, when they had smooth skin and not, instead, fancy "a bit of rough". It's certainly not a trait a chimpanzee or the sex-mad bonobos seem to find attractive. The same with those lovely curves. Perhaps there are better explanations ahead.
Another notch up from sexual selection is the really interesting and ultimately satisfying area of natural selection: adaptation. This is where Darwinism really makes most sense. What kinds of environment would we expect the features that make us different from apes to have some significant adaptive value?
This question has been the main focus of paleoanthropologists for over 150 years and for most of that time most seemed to have assumed that the environment in question was, for want of a better term... savannah.
Now this is where we get to the interesting part. But I'll cover that in my next posting. And, of course, that's where I hope to show that waterside explanations are the only ones that are ultimately most satisfying, four notches up from creationism, three from random drift, two from sexual selection and one about adaptive explanations of open habitat or fudgdey notions of "savannah-woodland-mosaics" (whatever they are).
Algis Kuliukas
Sunday, October 21, 2007
Wading into anthropology...
I've always been interested in human evolution - well, at least for as long as I can remember. My parents were from Eastern Europe, although actually "Central Europe" is a much better label. My name is Lithuanian and Lithuania lies at the geographic centre of the continent, whereas my mother was born in the Banat region of Romania which is also pretty central. Just about the only other thing they had in common was that they were both catholics and so, naturally, they started raising me as a good little catholic boy. Somehow though I managed to get enough independence of mind to resist the exercise of attempted brainwashing that went on around me every Sunday at St Thomas' Catholic church in Kirkby-in-Ashfield in the late 1960s. I am proud to say that at the age of eight I declared to my father that I no longer believed in God and that I wasn't going to church any more. The trigger was a 'lesson' at Sunday school about the origin of the universe. See, I was fascinated by the Apollo space programme and I'd been avidly watching my early scientific heroes Patrick Moore and James Burke on television talk about space and the solar system and such like. My parents had bought me a two inch refractor telescope which I'd used to glimpse the moon and other celestial bodies on our lawn and so naively I looked forward to learning more about how the universe had begun at church.
It was the first time (of many) I remember feeling like a sucker. The 'teacher' - who must have been all of fourteen - told us that God created the universe and that was that. I remembeer putting my hand up at the end of the 'lesson' and asking "If God made the universe, who made God?" The reply - "ah well, God's always been there" - just didn't ring true and I immediately felt that the whole thing was just plain wrong. When I told my dad that I wasn't going to go to church any more he wasn't very impressed but, to his credit, he didn't get angry or try to force me to go - not physically anyway (but then again he was a paraplegic, having had a mining accident four years earlier.)
Dad did not give up completely, however. My sister told me, years later because I'd forgotten, that the priest actually came round to our house the next week specifically to see me and tried to persuade me of the error of my ways before it was too late and my soul might be on its way to the eternal flames of hell. Apparently The Holy Father came out of my room after half an hour spent with me shaking his head muttering "he thinks we came from monkeys". I followed, in floods of tears, but remained determined that I had to see some evidence before I'd believe in it all.
I think that would make a pretty good foundation for a life in science. Unfortunately I kind of lost my way after that. To cut a long story short, although I did end up doing a Zoology/Pharmacology degree at Nottingham University quirks of fate diverted me into working in Information Technology instead, specialising in databases, noteably Microsoft Access and SQL Server for over twenty years. As luck would have it though, events would ultimately lead me back towards the field of human evolution which I really should have persued.
I was fortunate indeed when I married a beautiful and wonderful person - my wife Lesley who is a midwife. We already had three children when, on bonfire night 1995, my eldest, a boy, asked me "Dad? When did humans start using fire?" I was embarassed that I didn't really know but vowed to try to find out. Over the weeks that followed a spark was truly ignited and my interest in huamn evolution was rekindled. The final piece in the jigsaw arrived on 28th December when Lesley gave birth to our youngest daughter, at home, in front of a glorious fire, with classical music playing and red wine flowing. Being a midwife, Lesley had decided to hire a birthing tub to make the experience a little more comfortable. Rozalija was not actually born in the water but it helped Lesley get through the pains of labour, that's for sure.
So, that night as Lesley recovered from her traumatic day and little Rozy, a tiny scrap of pink flesh between our bodies made sweet little muzzly noises during the night, my mind raced. 'Why would women want to give birth in water?' 'Wasn't there a documentary we'd watched recently about all this? - by Desmond Morris?' I woke the next day determined to find out more. Another stroke of luck was this thing right here - the internet. Being an IT guy meant that I wasn't intimidated by new technology and we'd started to get into it even then. I searched for information about this idea and soon enough I began to find out about this woman called Elaine Morgan and this wierd sounding idea called 'The Aquatic Ape Hypothesis".
I was hooked. The more I learned about it the more interested I became and the more puzzled I was as to why I'd not been told about this at school or even at university. I soon had read all of Elaine's books and the 'aquatic ape theory' had become my latest obsession. Right from the beginning I understood the idea to be suggesting that our ancestors had been more aquatic in the past and in no sense 'truly' aquatic in the way that a seal or a dolphin was. It seemed bizarre to mee that so many people seemed to have simply misunderstood this basic point. But then again it seemed bizarre to me that so many millions of people continued to believe in God and hadn't, like me, realised that that idea too was a complete misunderstanding.
Lesley endured my rantings about the subject for several years before she had the brilliant idea that if I was so interested in this thing why didn't I go back to university and study it?
That is exactly what I did. I wrote to Professor Leslie Aiello the then head of Anthropology at University College London (UCL) and before I knew it I was back at university attending lectures, making notes and writing essays. Wonderful it was too. I doubt there was an anthropology student there at the time as enthusiastic as I was and I sailed through the one year taught MSc course in Human Evolution and Behaviour, passing with a distinction.
I went back to academia to find out why the so-called "aquatic ape hypothesis" (AAH) had been rejected but all I discovered was that really it had just been misunderstood. I remain convinced about that now, in my fifth year doing a part time PhD at the University of Western Australia (UWA). The only thing that has changed today is my enthusiasm to battle against people about it.
I have had a web site for years (www.RiverApes.com) that tries to promote what I call a "mild and moderate" form of the AAH and just today I came across an impressive blog which posted a very interesting interview with Frances White about bonobos and I though that perhaps I should set my own up too.
So, every now and then, when I feel like ranting, I'll post something here to promote what I think should be called "the waterside hypotheses" of human evolution. I'm sure it will make bugger all difference to the big picture but, at least it might make me feel a bit better.
So on these pages, expect to read me wading into the absurdities of anthropology and that although this field of science really cannot say what caused the clear and remarkable ape-human differences we see, the anthropologists who make it up are never-the-less apparently absolutely certain that they have nothing to do with moving through water.
Algis Kuliukas
Perth, Australia
21st October 2007
It was the first time (of many) I remember feeling like a sucker. The 'teacher' - who must have been all of fourteen - told us that God created the universe and that was that. I remembeer putting my hand up at the end of the 'lesson' and asking "If God made the universe, who made God?" The reply - "ah well, God's always been there" - just didn't ring true and I immediately felt that the whole thing was just plain wrong. When I told my dad that I wasn't going to go to church any more he wasn't very impressed but, to his credit, he didn't get angry or try to force me to go - not physically anyway (but then again he was a paraplegic, having had a mining accident four years earlier.)
Dad did not give up completely, however. My sister told me, years later because I'd forgotten, that the priest actually came round to our house the next week specifically to see me and tried to persuade me of the error of my ways before it was too late and my soul might be on its way to the eternal flames of hell. Apparently The Holy Father came out of my room after half an hour spent with me shaking his head muttering "he thinks we came from monkeys". I followed, in floods of tears, but remained determined that I had to see some evidence before I'd believe in it all.
I think that would make a pretty good foundation for a life in science. Unfortunately I kind of lost my way after that. To cut a long story short, although I did end up doing a Zoology/Pharmacology degree at Nottingham University quirks of fate diverted me into working in Information Technology instead, specialising in databases, noteably Microsoft Access and SQL Server for over twenty years. As luck would have it though, events would ultimately lead me back towards the field of human evolution which I really should have persued.
I was fortunate indeed when I married a beautiful and wonderful person - my wife Lesley who is a midwife. We already had three children when, on bonfire night 1995, my eldest, a boy, asked me "Dad? When did humans start using fire?" I was embarassed that I didn't really know but vowed to try to find out. Over the weeks that followed a spark was truly ignited and my interest in huamn evolution was rekindled. The final piece in the jigsaw arrived on 28th December when Lesley gave birth to our youngest daughter, at home, in front of a glorious fire, with classical music playing and red wine flowing. Being a midwife, Lesley had decided to hire a birthing tub to make the experience a little more comfortable. Rozalija was not actually born in the water but it helped Lesley get through the pains of labour, that's for sure.
So, that night as Lesley recovered from her traumatic day and little Rozy, a tiny scrap of pink flesh between our bodies made sweet little muzzly noises during the night, my mind raced. 'Why would women want to give birth in water?' 'Wasn't there a documentary we'd watched recently about all this? - by Desmond Morris?' I woke the next day determined to find out more. Another stroke of luck was this thing right here - the internet. Being an IT guy meant that I wasn't intimidated by new technology and we'd started to get into it even then. I searched for information about this idea and soon enough I began to find out about this woman called Elaine Morgan and this wierd sounding idea called 'The Aquatic Ape Hypothesis".
I was hooked. The more I learned about it the more interested I became and the more puzzled I was as to why I'd not been told about this at school or even at university. I soon had read all of Elaine's books and the 'aquatic ape theory' had become my latest obsession. Right from the beginning I understood the idea to be suggesting that our ancestors had been more aquatic in the past and in no sense 'truly' aquatic in the way that a seal or a dolphin was. It seemed bizarre to mee that so many people seemed to have simply misunderstood this basic point. But then again it seemed bizarre to me that so many millions of people continued to believe in God and hadn't, like me, realised that that idea too was a complete misunderstanding.
Lesley endured my rantings about the subject for several years before she had the brilliant idea that if I was so interested in this thing why didn't I go back to university and study it?
That is exactly what I did. I wrote to Professor Leslie Aiello the then head of Anthropology at University College London (UCL) and before I knew it I was back at university attending lectures, making notes and writing essays. Wonderful it was too. I doubt there was an anthropology student there at the time as enthusiastic as I was and I sailed through the one year taught MSc course in Human Evolution and Behaviour, passing with a distinction.
I went back to academia to find out why the so-called "aquatic ape hypothesis" (AAH) had been rejected but all I discovered was that really it had just been misunderstood. I remain convinced about that now, in my fifth year doing a part time PhD at the University of Western Australia (UWA). The only thing that has changed today is my enthusiasm to battle against people about it.
I have had a web site for years (www.RiverApes.com) that tries to promote what I call a "mild and moderate" form of the AAH and just today I came across an impressive blog which posted a very interesting interview with Frances White about bonobos and I though that perhaps I should set my own up too.
So, every now and then, when I feel like ranting, I'll post something here to promote what I think should be called "the waterside hypotheses" of human evolution. I'm sure it will make bugger all difference to the big picture but, at least it might make me feel a bit better.
So on these pages, expect to read me wading into the absurdities of anthropology and that although this field of science really cannot say what caused the clear and remarkable ape-human differences we see, the anthropologists who make it up are never-the-less apparently absolutely certain that they have nothing to do with moving through water.
Algis Kuliukas
Perth, Australia
21st October 2007
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