General issues
Human ecological genetics is the study of the influence of environmental factors on inheritance patterns, based on the general biological laws of evolution. The belief that each single gene expression within all living organisms occurs in close interaction with the environmental factors is one of the paradigms of medical genetics.
The human environment has been changing continuously for hundreds of thousands of years. Man as a biological species with a wide reaction norm has adapted to its changes, while man as a thinking creature actively changed the elements of his environment. Genotype selection occurred simultaneously at the group and population levels. The environment ensured the selection, survival, prosperity of populations or groups of people, according to their hereditary characteristics. Human evolution went through evolutionary changes in human genotype, shaping its biological nature. Man as a social and biological being has adapted to environmental change from a primitive cave to a modern cottage.
The humans gradually turned from hunting and gathering to more efficient food production (breeding of useful plants and animals). This made us less dependent on the struggle for existence, and therefore natural selection acquired characteristic human features.
Environmental exposures may lead to the following adverse health effects:
- hereditary structural changes (induced mutation process);
- pathological manifestations of gene expression in response to specific environmental factors;
- changes in the gene pool of populations induced by genetic imbalance between main population processes (mutation process, natural selection, migration (or gene flow), genetic drift).
Primary effects refer to a mutational process induced by mutagenic environmental factors in the broad sense, leading to an increased genetic variability rate among humans at the individual and population levels.
Secondary effects in humans are manifested as pathological reactions (diseases) at the individual level, and as high or low adaptability (acclimatization) at the population level.
Tertiary effects are the long-term changes in the population’s gene pool stretched over tens and even hundreds of generations. A biologically stable species is characterized by a constant balance of the basic genetic processes (mutation process, natural selection, migration, genetic drift). The modern period is characterized by a greater rapidity and volume of habitat changes, but human heredity at the population level cannot change so quickly. The changes in the gene pool of particular populations or humanity as a whole are the consequence of the high rates and large volume of human-environment changes (altered environmental conditions).