wlieberm@teknowledge-vaxc.ARPA (William Lieberman) (07/29/88)
As Jonathan Harris notes in his comment on my comments, environmental- genetic interactions are yet even more complicated than he felt I got across in my comments. He suggested, for example, that a scientist examining a youth with a vision problem which is correctable, but who for some reason has never obtained eyeglasses, would conclude the cause of the vision defect is genetic, whereas (if I remember his example correctly) had the youth had glasses, a scientist might conclude, let's say the youth performed baseball-well (my example) very well, that due to the youth's extraordinary visual system, (he hits so well), this is obviously genetic. To complicate it even further, it may very well be that even his vision defect was due to an environmental factor. In fact, there is some recent evidence, published in Science within the last year (I forget which issue) where in controlled experiments with some birds (pigeons??), by controlling the maximum distance the birds could see (by putting a kind of covered visual "world" around them - maybe a sphere or some shape like that - I forget), they were able to induce lengthening of the eyeball ( which is well known to exist in the vast majority of near-sighted people, thus being responsible for focus problems at a distance [the focus point is thus now in front of the retina because the eyevall is too long]). Thus, near- sightedness (myopia) may, after all, have a strong enviornmental component- the authors speculated on reading behavior at an early age - not enough variation in visual behavior. Kids should throw down the book for awhile and go frog searching - my example. (Of course, these findings, for the time being, only support conjectures about myopia - it is still a good deal aways from being demonstrated that the conjectures are true.) Thus, to me, and I think Jonathan's comment only butresses what I have said before, the only way to learn the truth in these matters is to do a direct physical examination of the behavior, molecule-type-by- molecule-type of all elements involved to see the unaffected or affected reaction of these molecules to all sorts of stimulation (read: enviornmental influences and genetic influences). A major problem right now is we don't know what to look for, even if we have the power to examine to the detail needed (and I'm not so sure about that, either.) But I believe, in principle, it's possible. Bill Lieberman