On the contrary, Genetic research has amply and extensively demonstrated the mechanisms underlying these transformations further bolstering the case for evolution. You seem to have been sadly misled. But no matter, eliminating ignorance and delusion is the prime duty of any Hindu.
So read on.The Genetic Mechanisms Behind Evolutionary Transformations 1
The first question in discussing how novel body forms (like arms and ears) can emerge from older body forms of ancestors is to ask the more current question:- How does the human, animal or plant body, each of whose cells have the same DNA sustain so many different types and shapes of tissues and organs?
The answer to that question is simple. Different stretches of the DNA is active in different types of cells. Thus a nerve cell will have a different stretch of DNA activates (and the rest passivated) in comparison to the heart cell. How does a cell know what to activate and what to passivate. It receives information from the outside regarding
a) What its neighbors are doing and
b) What geometric position it is in with respect to the body (especially within the growing embroyo).
These signals comes in terms of chemicals and chemical and osmotic/Ph (saltiness and acidity) gradients that turn on and off multiple switching genes and hence activate and passivate various stretches of the DNA.
What this means that the cells belonging to the limb (in adults) and responsible for growing the limb (in embroyos) will have a different retinue of activated genes and switches than corresponding cells responsible for the heart or the face and jaws for example.
The big discovery in developmental biology has been that:-
The cells responsible for the fins of fish are the same cells responsible for the arms and legs of animals in all cases. They have the same switching genes and the same activated stretches of DNA, and these switches and DNA stretches differ by only a few mutations from those of lobe finned fish in a way that show clear family relatedness. The entire mechanism of formation of fins and fomation of limbs are essentially identical with minor variations in themes caused by the mutations. When the older fin making gene versions are put back on these limb making cells of animal embroyos, they start to transform into finds rather than limbs (and vice-versa).
In the 1960-1970, very important embryological work identified two sets of developing tissue in any growing tetrapod embroyo (i.e. all animals with legs and arms or wings - birds, reptiles, mammals, amphibians) that governs the manner in which the limbs grow. They are the same tissue in all tetrapods. One controls the development of the limb itself. Remove it, and limb development stops. Add that tissue in somewhere and a new limb crops up. The other controls the development of the five-fingered hand (its called the ZPA). Add it to another part of the limb, and you will get another hand or feet, remove it and you will get a feetless or handless limb. After 1990, when genetic investigations became feasible, researchers began to look for the specific gene that gives these developmental tissue their ability to guide limb development. That gene proved to be the developmental gene called Sonic Hedgehog gene, and yes it is found to be active in the developmental limb buds of all tetrapods and yes, they are all mutated versions of each other showing clear signs of common ancestry. The DNA recipe to build upper arms, forearms, wrists and digits are virtually identical in every creature that has limbs.
I will continue the discussion further in the next post, but for those who are impatient, here is quick link
Limb Evolution
