One of my most current reads and the book that prompted this posting.When Darwin wrote “Origin of the Species” in 1859, he clarified and developed ideas that had been kicking around by those studying natural history and the origin of life, even the possibility of it’s evolution. Lamarck, von Humboldt, Darwin’s own grandfather, Haeckel and others had been speculating, arguing about certain pathways to ‘now’, but without having done that much serious research into life’s intricate relationships. There’s were less bold challenges or conceived theories. Christian orthodoxy shaped the thinking of the time, and opposing it, well that wasn’t done. Creation was pronounced a one time event, that all life forms that existed, had from the beginning by the grace and workings of God. But Darwin, himself a devout Christian, and Alfred Russel Wallace, did do the research, did examine the relationships in depth, adding their insights, the idea of ‘natural selection’, a process that ‘sorts’ through the accumulations of adaptations across a community and populations, ‘selecting’ those that give them a competitive advantage. These, over time would produce progeny at higher rates and would come to dominate a population and species. Since then one question led to another, as is the way of science. Where do these adaptations, these mutations, come from? How frequent are they? Aren’t our chromosomes ‘protected’ from this random degradation and mutation? Are mutations truly random? What drives them? Evolution ‘shows’ that over Earth’s 4.5 billion years, life has evolved towards greater complexity, organisms innovating new structures, variations and with it an increase in the sheer bulk of life, as more species create and fill more niches. Life on life. This can’t then be an entirely random event. Wouldn’t a truly random process result in no net ‘gain’? Wouldn’t it be a 50:50 proposition? One step forward, one step back? What is going on in this mutating?

Roxanne Khamsi, in “Beyond Inheritance”, takes the reader on a guided tour of our rapidly evolving understanding of the mutation of our cells and what it means. Mutation is an essential fact of life, one central to natural selection and the ongoing health of every living individual, and, perhaps our demise. Mutation, however, is commonly understood to be a negative, a degradation of the ideal held in our chromosomes. What’s going on here? Is it necessary or is it bad?
Mutation, it turns out, is pervasive. Every species, every tissue every cell and cell type is subject to it. We’re not talking about what occurs in ‘germ cells’, our egg and sperm,  those all important passers on of our genetic code. There are 30-40 trillion cells, in a mature human body, depending on our size, colonized by a like number of bacterial cells. These cells too, as they are going through a continuous process of metabolizing, internal and external maintenance, repairing and replacing themselves, are much more prone to mutation in this endless process of living. Some human brain cells are thought to survive over the course of our entire lives, but all of the rest, are being replaced at widely varying rates. Those epithelial cells of our intestinal lining are replaced every 3-4 days; we replace around 170,000,000,000, 170 billion red blood cells in our bodies, EVERYDAY. Every single cell replaced in our body, requires that the cell replicate its DNA, the two sets of chromosomes each containing 3.1 billion base pairs, the rungs in the helically shaped ladder of DNA’s structure. 3.1 billion base pairs, each consisting of a specific four ‘letter’ group of Adenine (A), Thymine (T), Guanine (G), and Cytosine (C), a 4 digit quarternary code….Perfect replication of each cell, billions and trillions of times over our lives…‘mistakes’, mutations happen. Organisms, cells, are not machines. We have this idea that machines can perfectly produce products endlessly, but that is wrong. Our continuous ‘cloning’ of our cells is far more precise a process. As the bumper sticker once so popular used to say, Shit happens…and the numbers within a complex, multi-celled animal such as ourselves, are astronomical. Mutations happen. We get stressed, sick, exposed to toxic substances, free radicals, physical trauma, various types of radiation, we age, become sedentary, our systems slow, we slow…as the necessary processes of life go on, within bodies and cells. Most must replicate themselves perfectly over our lives. Nevertheless, given the numbers, mutations accumulate. Some of these enable our continued ‘good’ health, some are benign, while others become ‘negative’ change agents, altering the operation and conditions within us, in what can be very harmful ways. Continue reading →