Turned up to eleven: Fair and Balanced

Wednesday, May 29, 2002

Tying threads together
I don't know if this will make much sense to anyone besides me, but it occurs to me that there is a common theme between my "battles" over Evolution, and my "battles" over Intelligence (I put those in quotes to remind myself that everyone involved has been, for the most part, very civil about both of these rather touchy subjects). Both differences of opinion are derived, to some extent, to the very vexing question of "Genes vs. Environment". This is probably more obvious w/ Intelligence, so I will start there. It is known, of course, that the structure of the brain must be encoded in the genes (of course, only strict materialists such as myself and "Godless" would make this assertion), but it is also known that environmental conditions are very important (even the most ardent hereditist assesses the heritability of Intelligence at ~50%, so the role of environment is crucial). We don't know how this almost certainly very complex interrelation works. "Godless", in one of his early posts, put forward the often cited view that genes provide for a range of intelligence, and environment decides where you fall on that range. This is a very straightforward model, and I think therefore mistaken. It strikes me that the process is iterative, rather then single steps (genes go first, then environment). For example, it could be that some set of genes turns on just after birth to start cortical development, and then at some key point a decision must be made based on environmental factors. If the environment is rich, a switch is turned one way (say, toward abstract thought), but if it is poor, the switch goes another way (say, toward simple survival strategies). This is all hypothetical, of course, but I can envision a branching tree (a decision tree, if you will), with a resultant g value depending on the environment at various points, and genetic makeup at various points. Of course, this only accounts for one facet of intelligence (ha! you thought I had gone to the dark side, didn't you?), but this model can get infinitely more complex if the specific genes for specific brain regions or neurons or ganglia interact with specific environmental factors at specific times, and the combinations of these things give rise to the final brain structure and function.

That may not be very clear, but all I mean to say, without getting too bogged down in specific models of intelligence or consciousness (again!), is that the interaction of genes and environment, in many cases, is bound to be much more complex, driven by feedback loops, and iterative processes, then the common conception.

So, how does this apply to Evolution? Because of the power of genetics to tell us about diseases, about physical characteristics, and about the living world around us, many people are tempted to think of Evolution by Natural Selection as a genetic model, when it is really a mixture of genes and environment. In all of the discussions I have gotten involved in, the question is always "How can genes do this or that?" or "How do gene mutations add information?" (this is the most recent, quasi-sophisticated question). Although there are good answers to these questions (I and many others have already given them, as recently as this afternoon!), they miss an important point about evolution, that has been made popularly by...you guessed it! Stephen Jay Gould! In his book Full House, Gould makes the argument (its not his argument, I stress) that Life does not progress in a line from simple to complex, but rather spreads and adapts to fill niches by mechanisms that are neither linearly derived from their antecedents nor necessarily efficient in terms of resource utilization. Life adapts to its circumstances, and competes based on a set of rules that can change at any moment, making adaptation to the old environment useless. So environment clearly plays a role in the evolution of any organism, including humans. Not only that, but it is a classic fallacy of logic to assume that because an organism now uses, for example, its second finger for pointing, that that is what it was evolved for (what would the middle finger have evolved for, then? Ha Ha) Based on the long time scale of evolution (geologic time), it is not unreasonable to predict that we could see evolution of limbs for certain tasks which they were not originally "designed". The canonical Gouldian example is the Panda's thumb, which is actually an elongated wristbone, the Panda having 5 additional digits. The Panda's thumb is not a thumb, in a skeletal sense, but it serves that purpose, not because it is the ideal bone to develop for stripping Bamboo, but because that is what a capricious Evolution tried, and it worked. (note, this, in less detail, was described in the Newsweek piece eulogizing Gould). I think the notion of Evolution=Progress needs to be fought, however, and Evolution by Natural Selection needs to be recognized as a description of the interactions of genes and environment over very long timescales, through the intermediary of living beings (including us).

P.S. For those who don't read a lot of pop. bio books, that last sentence was a semi-oblique reference to Dawkin's seminal book "The Selfish Gene", which (justifiably) guides the work of many biologists today.