How Environmental Contamination Has Changed the Course of Evolution
Since the beginning of the chemical revolution 70 years ago, over 80,000 man-made chemicals have been created, some making their way into the environment and posing a serious risk to both human health and wildlife. These chemicals have been classified by the Endocrine Society as endocrine-disrupting chemicals (EDCs), and defined as “any exogenous chemical, or mixture of chemicals, that interferes with any aspect of hormone action.” Today every body (human and animal) contains cocktails of these chemicals. This alarming fact is magnified by research demonstrating that exceptionally low levels of EDCs can be biologically relevant, especially if exposure occurs during critical life stages such as fetal development. The consequence is not toxicity and death but morbidity and compromised quality of life, including sterility. EDC exposure does not change the DNA itself but how DNA is regulated (a process called epigenetics), having an everlasting effect that potentially can affect all descendants.
What we want to discuss here is the effect of EDCs on evolution and show how present evolutionary theory, developed and codified prior to the chemical revolution, does not account for life in our contaminated world.
Evolutionary theory accounts for the process of change in life forms. It has had two epochs, with a third emerging. The first, known as Darwinian evolution (1800s), established the principle of change through natural selection. The second, called the modern synthesis (1900s), provided the units of heredity and their control, particularly change in DNA by recombination and mutation. The Mendelian geneticists effectively overthrew the Darwinian naturalists who emphasized the importance of the environment in shaping the phenotype. With the focus on genetics came the belief that evolution required fundamental changes to the unit(s) of heredity. The discovery of the structure of DNA gave credence to the idea that the genes themselves were the bricks from which the phenotype was built. This became the bulwark of the life sciences for the 20th century, with molecular biology and genetics the dominant disciplines in biology, a fact that continues today. Arguably the greatest discovery of the modern synthesis has been the remarkable conservation in the genetic code that links all animals.
(Source: The Huffington Post)