Have you ever wondered why a gold fish in a bowl only grows so big and if you put it into a big pond outside, it grows quite large? How could Darwinian natural selection account for such a phenomenon? I will try to explain why it doesn’t and at the same time – why your goldfish gets bigger in a bigger pond – Warning, it will not get smaller if you return the giant beast to its original bowl. It is a fully grown fish and will die. This trick only works on young, developing organisms. (There, I’ve given you part of the answer).
The other part of the answer is that this phenomenon has everything to do with the environment that the developing creature lives in. It has to do with the temperature, the food resources, the size of the environment, how many mouths to feed. In a nutshell: What changes take place in the organism’s outer world, totally affects the creature itself. Recent studies are beginning to show how environment can act upon an organism’s gene expression and therefore be a driver of evolutionary change (genes stay the same, but their expression can make big outer changes). This phenomenon is called EPIGENETIC . More info on this dynamic interaction between the organism and its environment and general discussions of the process can be seen in articles and discussions on this blog).
These mechanisms of change are dynamic and highly adaptive and relatively rapid. In other words, these evolutionary processes are quite NON-DARWINIAN to say the least; have very little to do with NATURAL SELECTION, and when epigenetic mechanisms are triggered, they can have a lasting and profound affect upon an organism. An article in the Guardian outlining the fact that fish are getting smaller because of warming seas is, in my educated opinion, a good example of this epigenetic process – HOW else could it have happened so fast? Surely not via the millions of years it takes for a random mutation to just turn up at the right time and eventually get preserved within an entire lineage of FISH??
My point being: if temperature can rapidly change a species size and determine the sex of some lizard embryos via epigenetic controls of existing genes (switching some on, others off etc) for example, why can’t epigenetic processes not be an alternative way of understanding evolutionary change? After all, you don’t need to change the whole creature slowly over thousands of generations, you just need a large enough environmental trigger to kick start those jumping genes into action and simply get the existing (relatively fixed gene sequences) to express itself differently by changing its software program instead. It is simpler to re-write code than make new hardware, but what if the highly adaptive code could update the 3D printout according to raw material availability and according to the newest market (environmental demands and changes)? Wouldn’t that be COOL?
Well, in a sense, that is what evolution seems to have been doing over the past few billion years. All you have to do to make a change in a creature is to write a different program to make certain proteins, turn some genes on, others off and you don’t even have to tinker directly with the mother board! (the gene sequence unique to each of us – except if you have an identical twin), but epigenetic factors will make you look, act and get different illnesses, if you are that unfortunate, in the end – Environment acts upon all of us. Epigenetics in developing organisms/or in earlier stages of evolution can have a much more profound effect – it can trigger gene sequences to make the creature bigger, smaller, or even become male or female, you just have to tweak the ambient temperature and in turn, the genome itself will express dramatic results.