This view of life
Spring is such a wonderful time of year, a time of birth and renewal. Something tells me that it is perhaps easier for most of us to appreciate the former of these occurrences. One allows ewes and rams to co-mingle for several weeks in the fall and, come spring, lambs arrive. But perennial plants are able to lay dormant over winter and, at the appropriate time, break dormancy to return to the business of growth and reproduction. Sure we know of diapause and every school kid has learned that bears hibernate through the most difficult weeks of winter. But plants do this in such a remarkable way that it is important to take special note. Consider, in a physiological sense, what a plant must do to ensure winter survival. First, it must manufacture stores of carbohydrate to support some minimal level of physiological activity throughout the winter. No growth. No reproduction. The organism must generate enough ATP (the energy currency of cells) to stay alive. Second, deciduous trees must do chemical inventory and withdraw everything of potential use from their leaves and then jettison them (the leaves) as winter liabilities. All of that material, along with the nutrient stores, must be transported down and into the roots. Once all of this is complete imagine that genes which were active during the spring and summer must be turned off and, at the same time, genes involved in baseline physiological maintenance must be turned on. And, these cascades of activity must be reversed come spring. Consider, that all the genes involved in these activities are in every cell. Have you ever stopped to consider that each and every one of us started life as a single cell? That cell had two complete sets of DNA, one from Mom and one from Dad. That single cell gave rise to the many trillions of cells which now comprise your body. Although the constituent cells of all of your organs have the very same DNA, these cellular sub-populations behave differently. How it is that muscle cells behave like muscle cells and liver cells behave like liver cells if, in fact, all of these cells have the same genetic material? All of the appropriateness of plant physiological response is dependent upon the expression of certain genes and the suppression of others. It turns out that gene expression may be influenced by the cellular environment within which any particular cell happens to find itself as well as in changes in any number of other environmental variables (biotic and otherwise). How wonderful life, in its myriad forms, really is. I find myself, several times during the academic year stopping in the middle of lecture. No matter whether discussing counter-current exchange in the molluscan ctenidium to one group or chromosomal nondisjunction to another, I’ll stop, look up and into the surprised eyes of my students and ask, Isn’t this elegant? I’ll plainly admit that I couldn’t devise anything more so. All of life’s solutions are ancient and optimized. I could continue but will, instead, end by quoting the very last sentence of Darwin’s monumental work, On the Origin of Species. Not many recognize these words as Darwin’s own summary of the elegance and beauty of Natural Selection, the phenomenon he explained to scientists and to the thinking world, more than a century-and-a-half ago.
There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.
All of nature is a wonder. Truly. To be lucky to know just a little bit of how it all works is a joy. To know its secrets doesn’t, to my mind, take away, but rather adds to my sense of wonder and admiration.