I wonder if you watched a recent TV program on dogs, how derived from wolves they have become 'man's best friend'. Part of the film showed how quickly this can happen, as portrayed by Belyaev's experiment in Russia with silver foxes - which in surprisingly few generations of breeding became either 'lap-foxes' or vicious 'devils'. This was purely by selecting for character, and without time for genetic mutations. The 'lap-foxes' noses shortened, their face becoming rounded and more cuddly.
This evolutionary story is in keeping with the perception of a number of scientists, among them of course, Crawford and Marsh, whose Nutrition and Evolution you presumably have read! In the last decade or two, the effect of environment on genes is being revealed. The mechanisms of gene methylation and histone acetylation have come to light. These switches provide a way of fine-tuning the system for the environment, but in our increasingly artificial environment and accelerating changes we are leaning on them too much, and we are recognizing problems from our failure to respect their way of working. Until recently geneticists considered the germline in both male and female to be insulated from environmental effects so that the species was stabilized from one generation to another. Over past decade exceptions have been revealed. For one thing human epidemiological studies have been showing effects over several generations of famine, especially in relation to conception. Famine in the slow growth period before puberty, and smoking too, have transgenerational effects, some gender-line, and surprisingly others trans-gender. These studies indicate significant biochemical effects of nutrition and toxins on gene-switches. Not surprisingly hormones too have well-documented effects on gene-settings. Among perinatalists, the roles of endorphins and oxytocin in the process of bonding between baby and mother especially at birth, have been common knowledge for a decade or two. Less well-known is the work of a cytologist who studied cell-memory for 13 years and became a psychiatrist. It has taken epigenetics research to lower the skepticism that thousands of his teams' patients found themselves marked for life by their mother's emotional state around conception. Considering the amount of gene manipulation during the period of gametogenesis and fertilization, such vulnerability is scarcely surprising. Genomic imprinting is a series of processes whereby the embryo is established with certain gene settings from the father, others from the mother. Reproduction involves major epigenetic changes in the oocyte, first after it forms within the grandmother, then as it matures for ovulation. Imprinting of the spermatic genome happens on fertilization. Genomic imprinting of the embryo is complete by gastrulation, a week after implantation. Yet epigenetic changes due to environment will continue, though reducing as the person ages, changes are due to pollution, nutrition and lifestyle - nurture plays a powerful role. We need the greatest consideration of medical intervention in reproduction, such as IVF, caesarean section and so on. At short notice I have been asked to give a clue about my talk following the AGM. I intend to fill out this note and provide references then, and in the next issue. Human-beings may not, like the silver foxes be getting longer or shorter noses, but we are emphatically noticing other changes in their shape, and in mental soundness. These things can happen quickly. Meanwhile it is worth watching the media for signs of how the brain is subject to the way we are changing the biosphere, as will be brought out by our next speakers, Izzeldin and Takehira. Simon House