The name ‘handicapped‘ is a bad-word in evolutionary biology because any phenotype which handicaps the organism gets eliminated in the long run. The handicap principle, as put by Zahavi and Zahavi, says that if an organism is strong and displays its strength to the predators risking his own life signaling that the predator would be wasting his time chasing the organism because the organism is strong enough to out-run him. So, the predator does not chase the organisms which exhibit their strengths and hence this trait survives in the prey’s population.

This theory, in my view, is flawed. First, there can be better ways of signaling (if it really occurs) the predator that one is strong without risking his life. Evolution, in the long run, would have found such ways. Second, why should there be any signaling from the predator to they prey at all. Even if the prey signals the predator, why does the predator believes it at all. I understand that in the long run if predators are not able to catch the prey because they are strong then (in the long run) they would not try chasing the prey that seems to be strong. But this is plain-jane natural selection. Who is handicapped here, the prey or predator? The answer is: no one. As mentioned earlier, a trait which handicaps the organism cannot be preserved in the population. There has to be some net-benefit for the organism from this seemingly handicap behavior. The theory should perhaps be called ’seemingly’ handicap principle. Moreover, there is no need for this theory at all. Every thing the theory says is accounted by concepts of natural-selection and sexual selection. Why do we then need this theory?

Can some organism be more evolvable than others? Is there any kind of genetic capacitance built into organisms which prepares them to evolve at accelerated rates in case the environmental conditions become harsh? The above questions fall under the topic of evolvability. I define evolvability as the act of quickly producing more variations of itself by the organism when it is sensed that the conditions are not favorable to the organism. On the first thought, it seems obvious that being more evolvable is certainly more advantageous for the organism because it prepares the organism for the unexpected. It also can account, somewhat crudely, for the huge variations which we see on earth. But, this issue is much more delicate than that.
Can some organism be more evolvable than others? Is there any kind of genetic capacitance built into organisms which prepares them to evolve at accelerated rates in case the environmental conditions become harsh? The above questions fall under the topic of evolvability. I define evolvability as the act of quickly producing more variations of itself by the organism when it is sensed that the conditions are not favorable to the organism. On the first thought, it seems obvious that being more evolvable is certainly more advantageous for the organism because it prepares the organism for the unexpected. It also can account, somewhat crudely, for the huge variations which we see on earth. But, this issue is much more delicate than that.

The first and most important objection against evolvability arises from the fact that evolution cannot foresee future. As it is put by most of the evolutionary biologists, ‘Evolution is Blind’. This means that evolution cannot know if the future conditions will be harsh and thus prepare the organism for the same. Evolvability just cannot evolve for this purpose alone. Of course, it can arise as a secondary consequence of some mechanism.

Another serious objection raised against it is the fact that it cannot be maintained in a non-stressed environment. Why would an organism maintain the extra genes needed for evolvability if the environment is stable? For evolvability to be maintained in the organism, it must be stressed at regular intervals of time and for brief periods. The word ‘brief’ is important here because if stressful conditions are maintained for prolonged periods the organism might just evolve specifically for those conditions and then we cannot call it evolvable anymore. I guess computer simulations or mathematical models can help elucidating the mechanism by which evolvability can be evolved (if it evolves at all).

There is also a philosophical aspect of this problem. Consider the following situation. Let us imagine an organism which has a trait making it prone to more mutations in case the conditions are made deleterious for itself. However, most of the mutations will be harmful for the organism. So, either the organism should know which mutations are beneficial and then specifically cause those mutations alone or the growth rate of organism should be very high so as to compensate for the other mutated organisms which are dead. The first case doesn’t make sense at all. How can an organism (apart from humans) target specific mutations in its genome? However, you may wonder that the second case is what exactly happens in viruses, or some bacteria. But it should be noted that for this case the organism should somehow sense the change in environment and then kick start its mutational machinery. This is not what really happens. It is just the case that mutations are happening at normal rates and the surviving organisms are just selected for being the fittest. In the case of evolvability, what should really happen is that environment should induce an increase in mutation rate in the organism. The fact, however, says that al the organisms in the word work towards preventing mutations because they are so harmful. That is why we have so elaborate DNA damage repair systems. Why would any organism care to repair its damaged DNA if evolvability conferred any true advantage?

In the end, I want to point out that it is not very fair to take a stand against evolvability in light of the fact that we haven’t understood the mechanism of evolution in detail. It might be the case that evolvability is slowly building up in the organisms in much more elegant fashion that I just mentioned in preceding paragraph. It might also be some kind of meta phenomena working on rates much slower than evolution rates. Maybe evolvability is a long term product of evolution. We certainly need more studies, simulations and models to prove or disprove evolvability.

I have found a report on computational biology on the internet. It is really a very detailed report which includes discussion of many aspects of this field. It has chapters on Computational Modelling, Biocomputing, Bioinformatics, etc. Click here.

I saw this absolutely stunning documentary movie called ‘March of the Penguins‘. It shows the complete lifespan of the Emperor Penguin in the Antartica. The mother and father fight death and cold so that the baby may survive. Everything they do makes perfect sense from an evolutionary point of view. The movie is a must watch. You will discover more about the nature of evolution that you could even dream of.

But one thing I couldn’t understand is that the fact that the mothers who lose their babies steal babies from other mothers. This doesn’t make sense. There must be some explanation for this, if not this trait could not have survived in the long run.