One of the more difficult and technical fields one could choose to study is Evo-Devo, or the evolution of development. Briefly, it is the field that studies how genetic programs determine the developmental process, how these programs evolve, and how the types of programs available constrain the directions evolution can take. For example, if humans were to evolve wings (an essential impossibility for many reasons), Evo-Devo lets us make the clear inference that we would not evolve them as sprouting from our shoulders like angels, but rather as modifications of our arms. Why? Because in all tetrapods (i.e., eptiles, amphibians, birds, and mammals) there is a developmental program to produce four limbs. Limbs can be lost (snakes, whales) and modified for flight (bats, birds), but they cannot be added.
One of the key insights to emerge from Evo-Devo is that developmental programs are highly organized. They have evolved ways to facilitate future evolution, called evolvability. They achieve this using mechanisms known as gene regulatory networks, compartmentalization, and canalization. While the details of these mechanisms are beyond the scope of this post, they have in common that they are ways to facilitate long-term evolution at the cost of flexibility. That is, they standardize the developmental process to give consistent results, but limit the forms that can be arrived at. Again, tetrapod limbs are a good example: if tetrapod limbs were not the result of a fairly standardized genetic module, we would be able to evolve them anywhere any time – the nose could become a hand, we could evolve rows of wings up and down our backs, etc. However, the result would be chaos. It would be too easy for a minor mutation to mess up development, too easy for the final form to depend too heavily on what gene combinations one has (image if parents regularly “accidentally” gave birth to children with 6 or 10 limbs, just because of how their genes got combined…), and too hard to control the evolution of limbs as the environment changed and a specific sort of form became necessary. In other words, we gave up flexibility for stability and predictability.
How does all this relate to Obamacare? Read the rest of this entry »