The current era of epigenetics has revealed a much more sophisticated and complex system of nature at play. Borrowing a charming and simple analogy from the website epigenetics.com, epigenetics can be described as the director of a movie where DNA is the script, and the cells are actors. The DNA sequence would be the words of the script, and certain combinations of these words would be the genes. Genetics could be likened to screenwriting while epigenetics could be likened to directing. The cells would be the actors and the actresses which followed the script of genetics, both effectively working under the direction of epigenetics.
Get the idea, right? To get a little more technical, geneticists tell us that only 3% of the DNA structure is involved in building the physical body through proteins. The rest 97%, usually referred to as ‘Junk’ DNA, act as switches, or the control genes. These control switches are in binary positions of ‘on’ and ‘off’, or like the thermostat indicators of ‘up’ and ‘down’. By switching on or off, they exhibit or inhibit a genetic characteristic. These control switches are affected by external influences from the environment, which could be favourable or adverse. Benevolent or malignant. Thus environmental pressure causes a ‘switch’ to change its state, triggering genetic modification or mutation.
Epigenetics suggests that pressure to adapt is the impetus for mutation. Also, rather than being a piece-meal process, mutation can proceed in quantum leaps. The best example for this idea comes from the book ‘Supergenes’, a comprehensive account of epigenetics for laymen like us, written by Rudolph Tanzi, professor of neurobiology at Harvard. In the book he tells us about a goat which was born with a peculiar abnormality of elongated hind leg bones. Strangely, the baby goat developed a human like S-shaped spine in only a year of its life, before it died in an accident. It even developed muscles attached to the bones like in humans. Limited by elongated hind legs, it was forced to move like a bipedal and developed aligned features. It had a broader, thicker plate of bone protecting the knee, and a rounder inner cavity of the abdomen, very similar to ours. All this physical modification happened in a year which is actually the most incredulous aspect of this anecdote. A fascinating example of real time mutation driven by need!
Environmental influences play an indispensable role in the progress of evolution as another examples suggests. We all are envious of the very Dutch characteristic of being the tallest people in the world, aren’t we? For them though, it is a fairly new feature. Surprisingly, the Dutch have gained an average of 20 cm of height only in the last 150 years, to make them tower over other nationalities. Natural selection might be favouring them all right, but why? It is noteworthy that in the last 150-200 years, Netherlands has become a very prosperous country, with all- pervasive income equality. The Dutch have become one of the largest producers and consumers of milk and cheese in the world, an integral part of good nutrition. Netherlands also has one of the best health care systems in the world. The importance of environmental influence on genetic modification gains further credence if you consider the effects the famous Dutch famine too. The ‘Hongerwinter’, as it was notoriously called lasted from 1945 to 55. Now the generation born after the hongerwinter was, oddly, more ‘fat’ than its parents. Children born after it were ‘fat’ as adults, as if to overcompensate for the lack of food their parents once faced. Did the ‘self-preservation’ gene kick in, as a genetic modification, across an entire generation?
Do you see how an external influence like the famine triggered a genetic modification across a whole generation in no random, piecemeal manner, but in a logical, quantum leap?
Also, the driving principle of Darwin’s theory- ‘survival of the fittest’, and ‘evolution for procreation’ fails to explain many stupefying characteristics in nature. In the ant world, there is a class of ants which is always sterile. They never engage in procreating, but perform some very specific duties in the ant colony. Even though they do not reproduce, they have never become extinct. Found in every generation, they fulfill a role of substantial importance to the survival of the colony itself.
Quite similar is the case of the worker bee in the beehive, one which puzzled Darwin too in its misalignment with his ‘survival of the fittest’ idea. The queen bees feed on ‘royal jelly’ reserved for them alone. It gives them high fertility and a longer life span. On the other hand the worker bees live shorter, they forage for food and tend to the queen and drone bees. They ventilate and protect the hive, thereby ensuring survival of the colony. They are born to perform these specific functional tasks only and are sterile as well. The queen bees with their longer life spans and high fertility might seem better poised for survival, but the worker bees never became extinct.
It appears that all classes of bees and ants have their own purpose for existing, over and above the obvious survival one.
Ants and bees apart, humans display cognitive and behaviour traits which are of no apparent use, of no consequence in the framework of Darwinian evolution. The impulse for art; music, poetry, dance; the urge towards symmetry and beauty.These have no survival purpose.The drive for aesthetic refinement, what evolutionary advantage might that have? Why do we possess these behavior traits, why do we have these notions? If life was merely about surviving and surviving well why do we feel the pangs of existential angst?
Why are we reaching for more to fulfill us? If evolution is just about procreating and spreading our genes alone why do we search for meaning?
Ask the logical intellectuals and they will tell you these impulses are tangential and peripheral matters. These personal conceptions have no relationship with the reality of this universe. In fact, they will tell you, evolution has no apparent purpose.
That just does not seem right, however hard they convince me with logic.The logic is flimsy anyway.
In a nutshell then, epigenetics tells us that there could be a constitutional organization in the process of evolution. There is evidence to support the thesis that when environmental challenges arise, the genome quickly adapts to compensate in necessary and non-random mutations. Quick enough for these changes to be effected in entire populations all at once. Non-random because the mutation is a direct, focused, response to a challenge. The input from experience, the influence from environment can speed up evolution to and makes it personal as well. Remember the goat with elongated hind legs?
This means that depending on the specificity and quality of challenges, different populations of the same species can evolve differently. It seems that evolution works as an interactive program, between the specie and its environment, as a self referring feedback loop. Evolution does not seem like a random, mindless system, but a PROGRAM, using feedback from the environment as a mode of learning and resetting.
To summarise, epigenetics (‘over genetics’ or ‘on top of genetics’), suggests the following:
a) Environmental challenges provide the impetus for evolution.
b) An external trigger can unleash a quantum leap in mutation, it may not always be piecemeal.
c) Evolution does not occur by random mutation, in fact it is a focused response to an external challenge.
d) A species, or class of species may have a function beyond its survival imperative, within a larger eco-system. This idea moves beyond the ‘survival of the fittest’ ideology.
It seems evolution is like a self propagating, self organising, self-referring feed-back loop. It learns and resets.