Morgan and Memes
Thomas Hunt Morgan in “The Fly Room” at Columbia University
In the early 20th century, a scientist at Columbia University, named Thomas Hunt Morgan did work establishing the connection between the observations of Gregor Mendel and some lesser known scientists, Flemming, Sutton and Boveri. Mendel, an Austrian monk, was the first naturalist to envision the systemic workings of nature and establish a clear, testable theory of how inheritance operates in organisms of all types.
Prior to Mendel, naturalists had been toying with a number of ideas about inheritance, including gene mixing (that a child inherits the average of its parents’ genes). However, problems plagued these explanations when suddenly genes would appear to unmix and present traits from several generations prior. There were also problems with reconciling the numbers that came from these experiments.
Trained in mathematics, Mendel was uniquely equipped to see through these apparent problems and grasp a more tenable explanation that was consistent with the data. If each trait was controlled by two ‘factors’ (one from each parent) rather than one, then the ‘problems’ with numbers in inheritance were not problems at all, but instead, pointed to a predictable pattern.
In his laboratory in Germany, totally unaware of Mendel’s work, Walther Flemming watched and documented the precise orchestration of cell division under the microscope. What he saw, less well known than Mendel’s work, was how chromosomes seem to form as threads in the cell that group along the center line of a cell before splitting and separating into each of the daughter cells formed by (Mitotic) division.
Meiosis, the form of cell division associated with making gametes (sperm and egg), was likewise being observed and documented independently by Hertwig and van Beneden. One might saw that the world was not ready to see these data for what they were — scientific consensus is a slow-moving machine.
Yet, as the 19th century gave way to the 20th, the minds of scientists were set to uncover the first basic, cellular, data supporting a mechanism for inheritance. Sutton and Boveri are credited with (independently) seeing the connection between these sorting chromosomes and Mendel’s ‘factors,’ but could not finish connecting the dots.
The next step was for Thomas Hunt, who concluded that chromosomes carry the genes — i.e. this is the physical location that Mendel’s genetics. To prove this he tracked two special chromosomes, X and Y and found that they determined the sex of the organism. Like humans, when flies had two X chromosomes, they were female; one X and one Y and they were male. Chromosomes were controlling the sex of the organism. This conclusion changed the way genetics was studied for years to come.
One thought that beguiled him though, was that Mendel’s work predicted that all genes sorted independently, but there were only so many chromosomes, and many, many genes. This was troubling because Mendel’s work was otherwise very clear and stood up to rigorous testing, yet it was inconsistent with what he saw with chromosomes. Physical locations for genes was to be a boon for geneticists, but being physical things, they had the limitations of physical things.
Mendel had said that all genes are randomly inherited — and here he was, working with fruit flies and finding that it just couldn’t be true with so many genes and so few chromosomes. His lab had been rearing fruit flies for some time searching for new traits that could be followed and described. To skip the details, Morgan, and his lab members eventually discovered that chromosomes are tricky — and sticky.
The two sets of chromosomes you get from each of your parents pair up and swap bits promiscuously. observations of meiotic cells showed this well. This swapping, or ‘crossing over,’ imitated randomness in all genes except those that were very close together. And so, while most genes adhered to Mendel’s law of independent assortment, those genes that lie close together on the chromosomes travel together and can be seen as traits that go hand-in-hand down the generations.
In 1976, Richard Dawkins, wrote “The Selfish Gene” in which he buried a nifty little idea. He proposed that thoughts can be like genes- he called them memes– that get passed along from one person to the next, taking on a life of their own in a sort of world-wide game of telephone. He has written often about this idea, which is an interesting analogy, but not altogether useful scientifically.
Nevertheless, I had the thought of memes in my head, when I came across an article about organic farming in the county paper some time ago. I suddenly realized that memes too travel together! In the article a farmer described her farm as organic and natural — all the things that I like to hear about. I was immediately excited and wanted to join her co-op to get food that was a little more a part of the earth and a little less a product of chemistry. But then I got to some ideas that just didn’t make sense to me — things that often travel with the less well informed members of the organic food crowd: She doesn’t vaccinate her animals — or her children. She went on to suggest that cancer and autism are causally linked to genetically modified organism (GMO) foods — a completely groundless hypothesis.
Yet, I’ve seen these memes travelling together in the past without giving it as much thought, and here they are again: The natural food meme and science-makes-us-sick meme. On one hand I see the connections the author was making, that GMO foods are unnatural and vaccines are a way of unnaturally generating immunity without being exposed to disease. But, GMO foods are not inherently unsafe. They simply put together traits that exist in nature, but in combinations that would take breeders eons to produce ‘naturally.’
I love to know that my food comes from a natural, organic farm. And I expect to pay more for food of that sort, mostly because it is not as abundant and does not take advantage of pesticides and herbicides. Yet I also understand that these are advances that make it possible to feed all the billions of people on this planet. Billions that could not all be fed without modern, scientific agriculture. But there is something wholesome about foods grown in this way: the great variety of fruits and vegetables with their subtly distinct flavors and colors. Like GMOs, vaccines are also something of an unnatural creation — unnatural creations that spare us from the all too natural world of smallpox, measles, poliomyelitis.
I don’t mean to impose my values on anyone (actually, yes I do), but I do think that it can be enlightening to consider what ‘natural’ means. There are many things from the past that we should not forget and good food is one of them, but we ought not to also forget the ravages of disease that once kept children from playing outside together in the summer months or made them deathly sick only to recover and lead a life blinded, paralyzed or otherwise retarded from exposure to all things natural in the world.
I don’t think that anyone leads an entirely consistent life, but we are intelligent creatures and we don’t have to accept anything without consideration. So take some time, examine what you believe in and see just what memes are in your head just catching a ride. Maybe there’s some cleaning out to do.