And what may i fill this blog post with?
Lets talk for a while about evolution.... I know, i know... that is not relevant to neurobiology... or at least, not directly relevant... But then most of what i say is not directly relevant to anything... :P
So! Evolution...
Evolution as a term refers to anything changing with time. Evolution in the context of biological systems also refers to change with time... However, in biological systems, it is not evolution if it is not hereditary... Thus any change that can be passed on from one generation to the next, contributes to evolution.... This is all pretty basic stuff but i like recapitulating basics... :)
Anyway, the question is not whether or not evolution occurs nor is its necessity questioned... The question is the mechanism of evolution. HOW the hell does it take place? Now i know you're going, "what's he talking about?? Everyone knows about natural selection!!" And you're right... in essentials. Evolution does seem to depend heavily on natural selection... What is not generally known, however, is that selection cannot possibly be the only mechanism driving evolution. The reasons for this are complicated and full of mathematical jargon and so i shall not delve on them. The point is to talk about the theoretical necessity for studying evolution in greater detail and with more rigour. It is no longer acceptable to say that in a population small changes occur in the genome and these, when passed on, result in speciation and thus, evolution... We must also resolve to prove, without reasonable doubt, that such changes occur or indeed are possible and that they, and they alone, are responsible for the immense diversity of species that we observe today. This is not in the least an obvious problem.
To demonstrate the complexity of this problem, let us take the example of Recombination and the role that it plays in shaping evolution. It is known that, of the millions of species that exist on earth today, only about 400 are asexual and have remained so throughout their evolutionary history. Saying that this difference in numbers of sexual and asexual species is vast is to drastically understate the situation. Obviously, there is some evolutionary benefit to be gained from recombination (which is the direct result of sexual reproduction)... But what can this advantage be?
On the face of it, recombination is an expensive process. The time and energy that go into making it work seem rather frivolous. The question, then, is to see if the benefits of recombination balance the costs or not? Such a cost-to-benefit analysis is necessary if we are ever to understand evolutionary dynamics.
As one of the reasons that recombination justifies the cost that goes into it we look at a mechanism known as "Muller's Ratchet".
What Muller did was to ask us to consider a hypothetical population of haploid, asexually reproducing individuals. Now the genomes of each of these individuals, though superficially similar, is different in its specifics. This difference is the result of random mutations only since no recombination is possible. Now if we consider that the current HIGHEST fitness individual in the population is subjected to some deleterious mutations which render him a mere shadow of his former self. That is, he is no longer as fit as he was and the SECOND fittest individual of the population now becomes the fittest. Notice that the highest fitness level in the population has gone down. Now, since there is no way that genomes from two individuals can recombine to form a higher fitness, the population has in effect forever lost the high fitness that it had and has no means of recovering its lost glory. Thus, by this mechanism, with time, deleterious mutations will continue to accumulate in the population bringing the mean fitness down with every such step. This is known as the 'Muller's Ratchet'.
Thus, as the complexity of the organism increases, recombination becomes a near necessity for the population to survive... It is somewhat akin to the winding mechanism used in old watches. It winds the mechanism again to make it work at it's optimum level...
More on this later.... I hope... :D
Thursday, October 02, 2008
Saturday, December 29, 2007
Tum humko kaho "Kaafir", Allah ki marzi hai :-)
Hi,
I was just sitting around and contemplating sectarian and religious violence today... This was after i heard news of Benazir Bhutto's death... I know that religious violence and her death are not directly related... But news of her death started me off thinking, albeit tangentially, about disputes between India and Pakistan... And that's when the irony of it all hit me... You see, there is no particular set of beliefs which can rightly be called Hinduism. The word "hindu" originally referred to people settled around the Indus River... a name given us by visiting arab traders... Hinduism then came to include the whole body of pagan beliefs of the people of the Indus Valley civilization... The irony ofcourse is that Pakistan separated from us on the pretext that if they stayed the Hindus would oppress them, however, their main source of water, their lifeline so to speak, is the very River to which the hindus owe their name and, some would argue, their existence as a separate religion.
Now, the reason this is important to me, is because of my interest in the psychology of people. For instance, if ever this post were to be widely read, there would be widespread debate by very ill-informed people on the veracity of my claims... What interests me is this... These people obviously know very little about their own religion, and much lesser about other religions and next to nothing about historical reasons for the flourishing of any religion... And still, they're strongly motivated to protest, to disrupt and generally make a nuisance of themselves at the slightest provocation. Why??? Granted there are some who do it for political power and some who do it for money and some who do it for both... but this still does not account for the ridiculously large number of people protesting this, that or the other on the world's streets and marketplaces everyday... What is it about religion that makes people want to go out of their house and hurl stones and burn things?? It is common for us to blame politicians for inciting the masses, but then we must also acknowledge the abominably low ability of the masses to rationalize their actions... Are we, as a race, that stupid??
This also brings us to the law of large numbers. Will we ever stabilise?? and what would stability, if ever it is reached, mean?? It could mean, for instance, a world consensus is reached on religion and everyone converts to this new world-religion. Or, it could mean that a few major religions become dominant and practitioners vow never to fight each other again and the situtation is frozen at that (unlikely, i know). Alternatively, the mean intelligence of the human race increases and we stop bothering about trivial and irrelevant things like religion... Or, we just kill each other and some other species becomes the dominant life-form on planet earth... Unless ofcourse we're already at the stable state, that being that a certain percentage of the population will continue fighting for exceedingly dumb causes and the remaining section will try, in vain, to leave all this behind.... Scary...
Cheers,
Adi
I was just sitting around and contemplating sectarian and religious violence today... This was after i heard news of Benazir Bhutto's death... I know that religious violence and her death are not directly related... But news of her death started me off thinking, albeit tangentially, about disputes between India and Pakistan... And that's when the irony of it all hit me... You see, there is no particular set of beliefs which can rightly be called Hinduism. The word "hindu" originally referred to people settled around the Indus River... a name given us by visiting arab traders... Hinduism then came to include the whole body of pagan beliefs of the people of the Indus Valley civilization... The irony ofcourse is that Pakistan separated from us on the pretext that if they stayed the Hindus would oppress them, however, their main source of water, their lifeline so to speak, is the very River to which the hindus owe their name and, some would argue, their existence as a separate religion.
Now, the reason this is important to me, is because of my interest in the psychology of people. For instance, if ever this post were to be widely read, there would be widespread debate by very ill-informed people on the veracity of my claims... What interests me is this... These people obviously know very little about their own religion, and much lesser about other religions and next to nothing about historical reasons for the flourishing of any religion... And still, they're strongly motivated to protest, to disrupt and generally make a nuisance of themselves at the slightest provocation. Why??? Granted there are some who do it for political power and some who do it for money and some who do it for both... but this still does not account for the ridiculously large number of people protesting this, that or the other on the world's streets and marketplaces everyday... What is it about religion that makes people want to go out of their house and hurl stones and burn things?? It is common for us to blame politicians for inciting the masses, but then we must also acknowledge the abominably low ability of the masses to rationalize their actions... Are we, as a race, that stupid??
This also brings us to the law of large numbers. Will we ever stabilise?? and what would stability, if ever it is reached, mean?? It could mean, for instance, a world consensus is reached on religion and everyone converts to this new world-religion. Or, it could mean that a few major religions become dominant and practitioners vow never to fight each other again and the situtation is frozen at that (unlikely, i know). Alternatively, the mean intelligence of the human race increases and we stop bothering about trivial and irrelevant things like religion... Or, we just kill each other and some other species becomes the dominant life-form on planet earth... Unless ofcourse we're already at the stable state, that being that a certain percentage of the population will continue fighting for exceedingly dumb causes and the remaining section will try, in vain, to leave all this behind.... Scary...
Cheers,
Adi
Wednesday, May 09, 2007
Rediscovered
Hullo all,
Well... the long delay was due to fact that i had forgotten my password. Ofcourse, i knew that such a contingency could arise when i was creating the blog. So, i had written the username and password down securely. BUT, i also forgot where i had written those crucial details down :P
This "oversight" of mine then brings us to the problem of why we forget? Or to put it differently, why we remember? (Although there is a subtle difference between these two questions and, thus, between their answers)
Ofcourse, evolutionarily speaking, we can see the advantage of having the ability to remember. Thus, we can say we know why we remember. This line of thought is undermined by the fact that there are hundreds of thousands of species on this planet and yet only a handful can boast of a memory power comparable to ours (humans). Notice that i refer only to our ability to memorise and NOT our intelligence. I have reason to believe that our claim that we are intelligent is not founded on fact :P Coming back to our discussion... We know that there MANY (more than i'd care to count, anyway) species which DON'T have any decent ability to memorise. And YET, they survive just as well, if not better and in bigger numbers, as we do... SO, our contention that it is evolutionarily beneficial to us to have a memory is true only if we take a very narrow view and guage its importance in our CURRENT state. There wasn't any reason for us to get to this stage in the first place. It was pure chance that brought us here. And, so, now we enter the realm of philosophy... and i don't wish to go there.
Maybe, for a more scientific approach (and by that, i mean an approach where we have reasonable hope of getting definite answers) we should try another question... HOW do we remember?? That would be more like it... Now we can enter the realm of molecular biology, synaptic interaction, cellular signal transduction etc. etc... Way cooler and much more satisfying in that at least we'll get SOME answers...
It is this that i wish to study... Will one of you PLEASE take me on as PhD Student??? I have finished my Masters degree in Biophysics... PLEASE????
Well... the long delay was due to fact that i had forgotten my password. Ofcourse, i knew that such a contingency could arise when i was creating the blog. So, i had written the username and password down securely. BUT, i also forgot where i had written those crucial details down :P
This "oversight" of mine then brings us to the problem of why we forget? Or to put it differently, why we remember? (Although there is a subtle difference between these two questions and, thus, between their answers)
Ofcourse, evolutionarily speaking, we can see the advantage of having the ability to remember. Thus, we can say we know why we remember. This line of thought is undermined by the fact that there are hundreds of thousands of species on this planet and yet only a handful can boast of a memory power comparable to ours (humans). Notice that i refer only to our ability to memorise and NOT our intelligence. I have reason to believe that our claim that we are intelligent is not founded on fact :P Coming back to our discussion... We know that there MANY (more than i'd care to count, anyway) species which DON'T have any decent ability to memorise. And YET, they survive just as well, if not better and in bigger numbers, as we do... SO, our contention that it is evolutionarily beneficial to us to have a memory is true only if we take a very narrow view and guage its importance in our CURRENT state. There wasn't any reason for us to get to this stage in the first place. It was pure chance that brought us here. And, so, now we enter the realm of philosophy... and i don't wish to go there.
Maybe, for a more scientific approach (and by that, i mean an approach where we have reasonable hope of getting definite answers) we should try another question... HOW do we remember?? That would be more like it... Now we can enter the realm of molecular biology, synaptic interaction, cellular signal transduction etc. etc... Way cooler and much more satisfying in that at least we'll get SOME answers...
It is this that i wish to study... Will one of you PLEASE take me on as PhD Student??? I have finished my Masters degree in Biophysics... PLEASE????
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