 Hello and welcome to NewsClick. In today's episode of Talking Science and Tech, our discussion is on the human thumb and we are joined by Praveepu Kayastha. The human thumb which is really just this evolutionary miracle which sets us apart from other species and has allowed us to develop all kinds of skills and abilities. And recently there was a new study which has been published in Current Biology of which Katerina Harvati is the corresponding author in which they trace the evolutionary history of the thumb and they talk about how 2 million years ago humans got this massive upgrade. So, to talk about this we have with us Praveepu, Praveepu, can you tell us about the key findings of the study first? Okay, of course as you know what might appear to be a small difference can have massive implications. So, is this itself the massive change or did it lead to a massive change is of course a different question. But if you see what essentially happened is that what is called the opposable thumb became biomechanically much more efficient. What does biomechanical efficiency mean? That it could exert a bigger torque. So, your grip became firmer, you could hold things more firmly and you could provide torque turning motion to it. Now in that doing that the reason that they discovered was the fact that the chimpanzee paradigm as they call it if you look at the chimpanzee's muscle the thumb that small part of the thumb in which this opposable action that develops this was a much smaller muscle than what the human muscle is. And therefore you could increase the torque that you are certain when you held a either a stone or a stick whatever you hold and you could assert a larger torque to it turn it around and it gave you a much finer control of the motion of the hand and the kind of work that we were doing. Let us remember that human tools this history is earlier than two million years. So you have the Australopithecus who have a hand which also goes to make tools. There are other hominid species which are around which also derive from a common stock but they also can make certain kinds of tools. And if you look at the chimpanzee where we split about five to seven million years back we split from that and the various hominid species emerge out of that split that all of them had some kind of construction of the hand which is in between what we have two million years back as it says and the chimpanzee's hand. And while the differences have been known what was not identified till now and that is why this paper is important that what constitutes the significant difference. So more or less it was understood that it was looking at the construction of the hand looking at the bones which are preserved in the fossils. So that record was compared to what the human hand today is or what the human hand would have been say million, two million, three million years back and what were structurally what seemed to be similar in terms of the bones the construction was thought to be the major issue. But here the difference that they have used is looking at the muscle and how they have constructed it will come to that later. And this is the major difference they have identified and the interesting part of this is the consequence of what I would call a relatively small evolutionary change and the consequences that comes about and that's what is also interesting that things which are big changes structurally or otherwise in species they may have relatively less impact. But small changes which appear to be small changes here can have consequences. Of course all of this starts from the fact that you stand up on two legs but that is something we have shared with other primates. So that's not something which sets us apart toolmaking now it's clear toolmaking this is not what set us apart also what really sets us apart from other species and that's why today other species or even primates are small in number and we are much larger in number is the fact that we had this finer control that we could assert in toolmaking and what Engels had identified quite some time back 150 years back as in his dialectics of nature the opposable thumb as basically the what differentiates us from other species and also that he also talked about it that it is not just that it is the that this allows us to do labor allows us to create tools but this is also the product of evolution and the product of human labor in fact he says it quite poetically that the hand is also the product of human labor it itself produces labor but it's also the product of labor so that I think is something which is interesting to see that modern science and the tools we have is confirming some of the conclusions again it was not something unique others have said it as well but it confirms that this was the key differentiator which sets us on a different evolutionary path and which is where we are today so can you also tell us about methodology that the study uses what all it's you know different samples different data that I had collected to come to this conclusion how how did we come here it's interesting because what they did was combine different elements of knowledge and put it together and what they put together was really a model of the muscle now the muscle doesn't exist in the fossil record so how did the first understand what the muscle would have looked like one is of course they have the chimpanzee hand which is available you know the human hand which is available and then you can see the transition between the two that is likely to have occurred so what they did was also look at the points the insertion and the origin points so these are the attachments to the muscle okay which is from here and from here this how the muscle at is attached to the thumb and then of course you compute that what is the force that it assert exerted so this also meant that they create a biomechanical model of the muscle and the hand and this is the interesting work that they did it's a combination of various elements of sciences so to say that the builder really biomechanical model they tested it with the chimpanzee hand and with the human hand they tested it with a number of other species record that they have fossil record that they have and they then tried to see that if you have a gradation between the two where would we put the major change and there it was that this is their major conclusion and that's two million years back that this is one significant change they seem to find and it's also interesting that you have the homo naledi that's another species which seem to have manual dexterity which is similar to the human the Homo sapiens but it had a small the relatively smaller brain size so it is not so much the intelligence which drives evolution that it's thought the brain which drives the dexterity it's really the muscle and the structural change that takes place that drove the evolution process and of course it does mean that at some point it means also you stand erect you have what would be called the evolution of the brain all of that will take place you have also since it's also the organ of labor it produces labor but also means it's also allowing for cooperation to take place in the human species so it is also an evolutionary impulse for other changes that would take place which would take place biologically as well so all of this as has been posited much earlier again I come back to it started with proposing the thumb is what makes human beings a tool making animal because it adds to dexterity and it give this is what they call by making mechanical efficiency or torque that you can have the twisting motion that that the hand allows and you have much time to grip as a consequence but all of that is difficult to deduce purely from the fossil record so the real change of understanding is creating this model the biomechanical model of the hand modeling it with existing hands existing chimpanzee hands all of it now they have criticisms of this method as well people have said well you know this is been known earlier and how correct is it to take the insertion points the size of the bones as a basis for the muscle that is one question mark what about other muscles of the hand can all of them combine to produce a similar effect of these are of course part of science that you raise because you have solved this particular problem it doesn't mean people accept that solution not doesn't does it mean that other problems do not exist in this particular solution so I think this is this is an interesting observation of the development of science itself when you solve the particular problem quotes within quotes all that it raises a certain set of other problems and it also is something which can be questioned and then we can test whether that this solution that has been offered is it the right one do other solutions exist which will give similar results or is there something which contraverts contradicts what we have got but the interesting problem the this interesting solution here is that it is needed various disciplines to look at what appears to be at the end an evolutionary biology problem and that always I think is interesting to show that how science today doesn't move in narrow disciplines but it needs a set of disciplines to make observations which could have major implications for a particular discipline and finally probably like you mentioned right in the beginning about the social consequences of us of a thumb being developed can you tell us more about that what kinds of abilities what brute did humans take after we got the thumb well we had the thumb so we got the opposable thumb yeah when you got a more efficient opposable thumb now the interesting part of it is the kind of social consequences that follow first is it expands the biological niche that we had that means you suddenly see that you can now do many more things that you would not have done otherwise so you get access to new foods you can break of course bones which you could do with rather big hammer-like stone tools which you had developed you now have the ability to scrape the skins of fallen animals or the animals you kill you have then projectiles that you develop to kill big animals which you otherwise would not probably hunt in fact it was argued that human civilization human beings started really as scavengers that you looked for dead carcasses killed by big cats and then of you acted like the hinders do taking care of whatever was left of after they had feasted so all of this is one part of it but you also got the ability to for instance break things break fruit shells pre-digests so to say by hammering various things and breaking the fiber so they become something that you can then eat so you your ecological niche expands so your ability to eat more food stuff or procure more food stuff expands there's also some record that fishing becomes more common after a certain point of this evolution so it can be conjectured maybe that one of the consequences also looking at fishes so all of this could be argued is a the advantage that humans got the early humans got from having an opposable thumb and of course there are others you know subspeciation that continues you have Nyanthathals you have modern humans they seem to share though the construction is slightly different from the hand they seem to share the biomechanical efficiencies so these are some of the things which would seem to indicate that this was a major driver of the ability of human beings to then develop more complex societies and it's also interesting the brain centers for speech so to say seem to arise after your hand had got modified and therefore the thesis that has been argued many times not that this is the this paper throws a new light on that this is something which has been discussed earlier as well that it is the ability to form complex groups or larger groups that requires communication for tasks which have to be done jointly that language is the necessity for complex organizations to be built and the complex organizations can be built when you have larger access to food and if you have larger access to food or you need to organize to get larger access to food then joint labor needs speech otherwise as you can if you can manage with a few set of sounds there is no evolutionary reason why you should develop sentences so there are animals which create quite a complex pattern of sounds and as we now know the birds have even a separate center of the voice they have another voice organ they can make complex sounds but the point is because they do not do coordinated labor therefore they don't have a language though they have the capacity physically to produce complex sounds or string a complex set of sounds together so this is the second argument that one of the major consequences not just enlarging the ecological niche that humans had but also the ability to perhaps coordinate with each other as a part of complex labor process and the complex labor process really came about because of ultimately the thumb thank you for joining us today in this discussion and that's all the time we have keep watching news click