Wednesday, May 7, 2008

Selfish Genes Made Easy (extract from WIP)

I just got a comment today (Yay! 1st one! Thank you Juliette!) and was quickly reminded of this blog's purpose: To educate. Me as much as my readers, coz the moment we stop opening our minds to learning, we cease to be human. All are welcome to comment, and of course, silliness in comments (a la Youtube or will be either deleted or ridiculed mercilessly :-)

Anyhoo, I consider evolutionary biology to be among the most important of the sciences, particularly in terms of understanding our place in the universe. And no living biologist has had quite as much impact as Richard Dawkins with his Selfish Gene. As such, I've extracted a chunk of my book, which attempts to give the reader a taste of the power of present evolutionary theory. Again, comments and feedback welcome, ESPECIALLY if I've made a boo-boo:

*extract starts*
The only way I could possibly write this without feeling tremendously guilty is by stating here and now that what I’m writing here is a drastically abbreviated account of one of the most amazing facets of modern evolutionary biology. As such, if, after my humble introduction you are in fact interested in learning more, then I must point you towards The Selfish Gene by Richard Dawkins. The long story short is as follows.

You are probably at the very least familiar with some of the basic premises of evolution, i.e. that it involves organisms slowly changing over the generations as they mutate and favourable mutations survive to breed future generations and less favourable mutations die out. The trick is to view evolution not from the point of view of the individual organism, but from the perspective of it’s DNA (or RNA in the case of simpler organisms, if you want to be pedantic). For simplicity, I’ll just refer to DNA and start my story in the middle.

Think of an organism, say, a cat. In order to make copies of itself, a cat’s DNA has over the generations, produced an organism with all the necessary traits for survival, i.e. limbs to get around with, a digestive tract to process raw materials, a reproductive system to create copies of itself, etc. From all outward appearances, a cat appears to be a beautifully designed machine.

Hundreds of generations ago, a cat may not have been quite as it appears to you today. Such a proto-cat would perhaps be less well-formed. And somewhere down the line, along comes a mutation - bigger ears, perhaps, or longer legs, rougher tongues or some such. What matters is how such a mutation contributes to our proto-cat’s chances of survival and here’s the bit where survival of the fittest comes in:

- If the mutation INCREASES the gene’s chances of survival, this new superior organism could become dominant and slowly replace the original.

- If the mutation DECREASES the gene’s chances of survival, odds are it expires before passing on its inferior genes to the next generation and that’s the end of that.

- If the mutation makes no real difference to the gene’s chances of survival, you get a possibility of a new breed of organism exploring a new evolutionary path.

When we look at the nature’s wonders around us today and think about the randomness inherent in natural selection, it’s easy to liken the result to rolling 1,000 sixes on 1,000 dice. How is such complexity and perfection possible? This is where most people with an inadequate understanding of natural selection go drastically wrong. The result is most certainly like rolling 1,000 sixes, but in the case of natural selection, it’s more correct to say that one rolled 1,000 dice, then removed anything that didn’t roll a six and rolled again. So, after the first attempt, going by simple averages, say 1 out of every 6 dice give you a 6. That gives you about 167 sixes, so you keep those, and reroll the rest. Here’s a quick table showing the results of each iteration:

Keep this up for long enough after a total of about 35 iterations you should have a fair chance at arriving at your 1,000 sixes.

By comparison, if you were to try and roll 1,000 dice and coming up all sixes the HARD way, that is, without this mechanism of selection, you’ll be rolling dice well into the 5th or 6th death and rebirth of the Universe and in all likelihood won’t come anywhere close.

The term Darwinism is often used to describe the process of ruthless judgement by Nature of an organism’s worthiness to exist. The bit where the selfishness of the gene comes in is when we observe that the purpose of the gene is to propagate itself, often with little to no regard for the organism carrying the genes.

For example, black widow spiders and praying mantises both practice mating habits that don’t end well for the male. An understatement, I suppose; the males get eaten by the female shortly after mating. From the point of view of the individual organism, this is, of course, very, very bad. However, it appears that this suicidal act increases the males’ chances of fertilising the eggs, and from the genes’ point of view, that’s all that matters.

Another example closer to home is the existence of junk DNA in our genome. About 70% of the human genome has no apparent purpose in the construction of an individual human. So why is it there? Very simple: that “junk” DNA does not “care” what it does for us. It’s there because it’s carrying out its purpose of replicating itself. Apparently, at some point in time, part of those genes’ survival strategy involved hitching a ride inside the genome of some hapless creatures (i.e. us), so there it is, freeloading on our genome to this day.

The selfish gene treats genes very much like incredibly advanced viruses, existing for the sole purpose of replicating themselves. The great diversity of life we observe today are a reflection of all the different strategies explored by genes to propagate themselves, each organism being a “survival machine”, to quote Richard Dawkins. This brings us to another fascinating concept, also introduced in The Selfish Gene: The meme.
*extract ends*

The thing to bear in mind is that the evolution of genes alone is NOT enough to explain the development of humans. We're a bit odd like that. An example I can point to is our brains, which are disproportionately large compared to those of similarly sized mammals. And they gobble a LOT of energy, too! Why humans, when other animals seem to get along fine without?

Stay tuned, and I'll (eventually) tell you a tale of memes. Alternatively, bugger off and pick up a copy of Susan Blackmore's The Meme Machine.


Rambling Alcoholic said...

Is there a reason why your fonts get progressively smaller? heh...

oh, i clicked on the ads. u made $$$.

Juliette said...

That is a good way of explaining evolution, but then again also coming from a scientific background there are no prizes for me understanding either...

Linking that with your previous post on idiocracy (which I thought was very funny and head on!), the other thing which is odd about human beings and evolution is that humans directly try to counter evolution by the welfare state. The welfare state allows society to take care of the poor/sick/young/old/disabled which in evolutionary terms would be doomed to become gradually extinct. I am not advocating for a Hitlerian regime whereby we would exterminate all these poor sods, and I do agree that you can't leave these poor people dying in their wretched state. After all, this precise difference is what makes us humans, and we can chuck in those arguments on religion and the "greater good" and atheists.... but!!!!

There are sometimes when I think that the current trend in western countries (at least in the UK and US) has been to actually promote stupid lazy people which is clearly not what evolution wants (and which would explain also why stupid people are here to stay!).
To give an illustration:
Woman not too brght but who has enough of a brain realises that unemployment benefits would pay far better than what she would earn, decides it is not worth working. She then finds out that for every child she has she gets additional benefits, to top it off, she even gets free housing! Hence the encouragement of these people to reproduce. Children brought up in such a milieu rarely turn out any better and so the trend continues...
Contrast this to somebody of the middle class extract, usually intelligent and educated specimens. Earns enough to disqualify from any government help, has a huge chunk of income taken out as taxes, but is not that filthy rich that he or she has the time or money to breed a huge flock of underlings. Result: we have a dying class...

ok, so I have generalised a few things (yes, not all people on the dole are stupid or lazy), but that was just to make a point.

BTW: no, I haven't read any Dawkins, but I am a firm believer in evolution despite what the Roman catholic church has to say on it!

Yikes! that was long!