As I walked pasture the other day I came across this empty Milkweed seed pod. In one way the empty receptacle speaks to the end of life and to decay. In another way however, and in dramatic contrast, this view foreshadows the inevitability of the seasons, the coming of spring and renewal; for surely the vegetable diaspora will respond to changes in day length, to the warming of the soil, germinate and grow. Until then however many seeds, especially those produced by plants living in temperate latitudes, need to experience a prolonged period of cold before they are able to germinate. This is called vernalization and is nature’s way of ensuring that seeds set in the fall do not germinate until spring. Such a sensible strategy, so elegant. But, allow me to back up to give seeds proper consideration; for, what is a seed? Is it an encapsulated, nutrient fortified, embryo. And what is an embryo? An embryo is encapsulated DNA. And what is DNA such that its expression leads to the production of embryos and individuals? The popular understanding is that DNA is the blueprint of life. To be sure, but that simply begs the question. How does DNA work? A detailed consideration of information flow from gene to protein is beyond the scope of this humble farm blog but perhaps, at the risk of having you pass quickly to the next post in your reader, you will pause long enough for a few of the essentials?
James Watson, Francis Crick, and Rosalind Franklin are well-known for having worked out the structure of deoxyribonucleic acid and Watson, Crick, and Maurice Wilkins shared the 1962 Nobel Prize in Physiology or Medicine for their work. Franklin died in 1958 and was therefore ineligible for nomination to the prize and has only recently been fully recognized as having contributed in significant and crucial ways to what may have been the most important scientific discovery of the twentieth century. If you look at the schematic below you can see that sugar (pentagons) and phosphate (in yellow) form the backbone of the DNA double-helix, the handrails of the ladder in the classic pedagogical analogy. Nitrogen-containing moieties are arranged in the middle of the molecule in repeated pairs, the rungs, Adenine/Thymine and Guanine/Cytosine. Now, here’s the really fascinating bit, the genetic code of life may be found in the specific sequence of base pairs. That’s it? … you say? Yup … it’s that easy … and differences in base sequences are responsible for the differences between Leonardo, Copernicus, Einstein, Newton, and you and me. These sequences code for amino acids which come together to form proteins. Sperm and egg are each comprised of 23 chromosomes which make up the Human Genome which has been estimated to be made up of over 3 billion base pairs. Although egg and sperm represent parental contributions to offspring consider that the real business of reproduction is the act of passing coded DNA messages between the generations. Genes aren’t legs, arms, and spleens … genes don’t confer bodies, as such. Genes represent coded information, information that may be expressed as flamingos, or elephants, or elm trees, or squid … generation after generation, across the millennia, and over millions upon billions of years. Bodies don’t do time travel but information does. The next time you see the tufted seed of a milkweed floating along with the breeze realize that what you are really seeing is encapsulated information, information which guarantees the perpetuation of genes contained within the plants which produced the seed itself. Perhaps it might give you something of different spin on life to consider that some would view our human bodies as simply a gene’s way of making another gene. In the text of The Selfish Gene author Richard Dawkins wrote … When we have served our purpose we are cast aside. But genes are denizens of geological time: genes are forever. Some would say that we live in an age of information. The truth of the matter is that the age of information has been around as long as life itself. When we do away with all the fluff, what remains are the capacities of all sorts of genes to make copies of themselves … and the diversity of life represents a myriad ways of doing this. And then of course there is the metaphysical question of why genes bother to perpetuate themselves at all. And the answer to that question seems to be that they do so because they can. And the nature of that reality is a fruitful topic of conversation for another day.