Friday, November 4, 2016
I have been reading Bernd Rosslenbroich’s book again: On the Origins of Autonomy: A New Look at the Major Transitions in Evolution. Rosslenbroich notes that Darwin himself confronted the paradox of progress in evolutionary history and attempted to solve it
A paradox occurs when the same phenomenon appears to present two, logically irreconcilable faces. On the one hand, common descent from an Ur organism seems to produce only an increasingly diverse number of branching lineages. As we survey the tree from bottom (earliest) to the top (presently existing organisms), each fork (plants fork from animals, mammals branch from reptiles, etc.) each new branch represents only the extension of original lineage into available ecological niches. The driving force is natural selection, which is altogether undirected. Evolutionary history flows, as flood waters do, around obstacles and into the next available plain. Okay, I am mixing metaphors; the point is, in this account, slime mold amoebas and certified public accountants are equal in ontological status in so far as they both made it to the present moment.
On the other hand, it seems obvious that multi-cellular organisms represent an advance beyond their single-celled ancestors, animals an advance beyond plants, mammals an advance beyond reptiles. If evolution is driven by an undirected, efficient causation, how can we understand these apparent advances? Darwin attempted to account for this by appealing to the idea of increasing fitness. More advanced organisms are better able to survive and reproduce; why else would they have emerged in the first place?
This explanation is untenable. Cockroaches are more fit in terms of natural selection than elephants, slime molds than slimy politicians. Darwin’s explanation fails. Many biologists have been tempted to try to give up the idea of progress altogether; however, they have been unable to do so. Ignoring the distinction between higher level and lower level organisms means ignoring a conspicuous feature of biological reality.
Rosslenbroich demonstrates that this is a persistent problem in the philosophy of biology. Biologists can’t do with and can’t do without a theory of progress. Among the attempts to model progress in evolutionary history are: increasing complexity, increasing division of labor among cells, increasing efficiency or energy intensive activity, increasing genetic information, and increasing body size. All seem to come up short of a satisfactory account of what distinguishes the lower levels of biological activity from the activities of the higher levels. Without that, how can we understand how sentient moles and heartbroken playwrights emerged from the primordial soup?
Rosslenbroich’s answer is increasing autonomy. The most basic feature of living organisms is that they build a barrier between themselves and their environment. The simplest living cell builds a wall around itself. Within that wall it maintains itself and controls interactions with the environment in order to resist equilibrium with its environment. If the external environment is too salty, the cell blocks the admission of salt and so maintains its less salty interior. If the internal self is polluted with waste, paste is passed on to the external environment.
The efficient cause of the movements of a fallen leaf are external to the leaf: the autumn wind. The efficient cause of the movements of a mouse or of the cat stalking the mouse, are internal to the one and the other.
Rosslenbroich argues that what distinguishes higher from lower organisms is increasing autonomy. The simplest cell builds a wall between itself and its environment and maintains the one against the other. More complex cells build internal walls, protecting the nucleus against the rest of the cell. Animals build walls around their organs and walls protecting brains and sex cells against the flow of energy and materials within the body. The walls don’t have to be material. A hive of bees distinguishes its social self from other insects.
I think that this is dead spot on. It explains the difference between the primitive and advanced organisms without any need to suppose a directed force in evolution. Just as tectonic plates collide to rise up into mountains, so the forces of evolutionary history pushed up in the direction of increased autonomy.
I also think that it holds the answer to a number of basic philosophical questions. To mention only one: the problem of personal identity. The psychological self is one more advance in the expansion of biological autonomy.