Extended Heredity: A New Understanding of Inheritance and Evolution
In grade-school science the first thing we were taught about evolution was to snigger at a picture of a giraffe straining to reach the single remaining leaf on a tall tree. It was silly to think that a creature could stretch its neck reaching for food and later give birth to a creature with an even longer neck. That ridiculous notion was called Lamarckism.
We went on to learn the tale of the moths of Manchester in order to understand the way evolutionary change really worked. The color of these moths changed from light to dark over the generations during which the bark of the trees where they lived blackened with coal smog. There had always been a few dark moths, but they tended to get eaten by predators because they stood out against the pale bark. When the trees darkened, the darker moths benefitted from their accidental camouflage and became the ones who survived and reproduced. This change in color demonstrated natural selection.
Pretty much everyone came to agree that evolution is the result of the natural selection of random mutations which allow the “fittest” to survive.
One day in 1963, an image of a DNA helix was delivered to homes all over the United States. On the cover of Life Magazine. The mechanism of heredity, variation, and evolution had been discovered. DNA–the stuff of genes–zips and unzips itself, initiating the processes that make proteins, protozoa, and people. Unlocking the whole mystery of how DNA worked would be a matter of filling in the details.
As techniques and technologies of microbiology advanced over the next 50 years, the secrets of DNA–how it can grow a puppy or evolve a human–were not revealed. DNA failed to emerge as the self-replicating bio-computer whose coding mistakes blanketed the planet with life.
Extended Heredity is a book written by scientists for scientists. It describes experiments and theories that broaden ideas about the way an organism develops and how it passes traits to future generations. Some of its suppositions and conclusions have caused critics to hiss, “Lamarckism!”
Much of this book was over my head. So many words to look up: soma, nucleosome, methylation, gemmule… But I could understand enough to grasp that the information is mind-boggling. Literally. It’s just not easy to take notions as calcified as those we call “Darwinian” and try to make them supple enough to imagine different ways that organisms truly do beget organisms.
Fortunately, Russell Bonduriansky and Troy Day, the authors of Extended Heredity, made multiple references to the work of Eva Jablonka and Marion Lamb who have both written about these matters in greater (and perhaps more accessible) detail. They authored a 2014 tome called Evolution in Four Dimensions: Genetic, Epigenetic, Behavioral, and Symbolic Variation in the History of Life. (Bonduriansky and Day say that the four categories of that subtitle are but one way of slicing up the evolutionary pie.)
Reading Extended Heredity was enough to whet my appetite. Studying Evolution in Four Dimensions has changed the way I see the world.