Recent research in the field of epigenetics is bringing to light information highlighting the extent to which environmental factors play a role in determining which characteristics or traits will be passed on to offspring.
Historically it was considered environmental factors did not play a role in altering the individual’s genes over the course of a particular species lifetime. Darwinism, traditionally proposed evolution being more dependent upon the population, in that genes were relatively stable over a lifetime and those genes acquired at birth would be passed on to offspring. Environmental factors within this framework have an effect in that environmental factors will eliminate those less suited to the environment removing those genes from the overall population of the species.
Although new research on epigenetics is not calling Darwinism into question, it is shedding new light on how genes might potentially react to the environment. This plays a significant role in those genes acquired at birth have the ability, essentially, to activate or deactivate dependent upon environmental factors. New research indicates it could potentially be those ‘activated’ genes which are then passed on to offspring.
An initial study of mice trained the population to fear a specific odor by the insertion of external environmental reinforcement. This population then went on to produce offspring who then exhibited signs of fearing the odor, even in the absence of the previous external reinforcement associated with the odor, in the former population. In addition to the initial offspring of those mice included in the study who were trained to fear the odor, up to four generations of mice exhibited an increased startling response with the insertion of the odor, even with the absence of the environmental reinforcement used to train the initial population.
A critical analysis of the study might propose socialization as the causation of the increased startle response to the odor, amongst the mice. Closer inspection reveals these traits were passed on genetically. Resulting offspring of the initial mice contained a higher concentration of M71 neurons which are necessary to detect the odor acetophenone, which the initial population of mice was trained to fear by external reinforcement. Additionally, the offspring contained a much larger area of the brain, M71 glomeruli, which is associated with the response to the smell. This is a rather outstanding observation, in that it highlights how a physiological response to environmental stimuli might alter an individual’s genes, which then may be passed on to offspring. This is an example of essentially, memories, being passed on to offspring.
Another study observed a population of Agouti mice. This particular population of mice had yellow hair, exhibiting a host of issues such as obesity, diabetes, and cancer. The pregnant Agouti females of this population were provided vitamin B12, folic acid, and choline prior to conception, and during pregnancy. The resulting offspring of these Agouti mice, not only did not contain any of the health issues associated with their parentage but were brown as well. Additionally, these offspring would then go on to produce healthy brown mice without the insertion of the vitamins associated with the initial population in the study. This study highlights the extent to which environmental factors may alter the gene pool of a population. Essentially the diet of these mice had an effect on how genes were passed on to the offspring, not through eliminating individuals in the species, but through an altering of the genes within the population.
Research is underway as to the specifics of how this process transpires. It is being considered that DNA may be ordered in a specific fashion, and within this ordering, component exists histones. Histones are considered a space-saving aspect of DNA, and dependent upon chemical groupings, histones activate or deactivate particular genes. Additional research is beginning to shed light on directly observing which specific genes are being activated and deactivated.
Research on epigenetics may prove relatively groundbreaking in terms of understanding the full extent to which an individual may adapt to one’s environment. Generically speaking the genes one inherits is not static, and may be reprogrammed, dependent upon environmental factors. This DNA would then be passed on to future generations, with the possibility of additional updates again, and again. In the context of epigenetics, one must wonder the full extent to which DNA may change over the course of a lifetime.