As we entered the new millennium, discussions surrounding the number of genes in our genome were highly debated. Initial estimates were significantly lower than anticipated, spurring a movement towards re-evaluating evolutionary processes.
The Human Genome Project revealed in 2001 that we possess fewer than 40,000 protein-coding genes — a number that has since been adjusted to around 20,000. This finding necessitated the exploration of alternative mechanisms to account for the complexity of our biology and evolution; epigenetics now stands at the forefront.
Epigenetics encompasses the various ways that molecules can interact with DNA or RNA, ultimately influencing gene activity without altering the genetic code itself. For instance, two identical cells can exhibit vastly different characteristics based purely on their epigenetic markers.
Through epigenetics, we can extract even greater complexity from our genome, factoring in influences from the environment. Some biologists are convinced that epigenetics can play a significant role in evolutionary processes.
A notable study in 2019 demonstrated how yeast exposed to toxic substances survived by silencing specific genes through epigenetic mechanisms. Over generations, certain yeast cultures developed genetic mutations that amplified gene silencing, indicating that evolutionary changes began with epigenetic modifications.
Epigenetics is crucial for expanding our understanding of evolutionary theory. Nevertheless, skepticism persists regarding its broader implications, particularly in relation to plants and other organisms.
For instance, Adrian Bird, a geneticist at the University of Edinburgh, expressed doubts, arguing in a recent paper that there is no clear evidence linking environmental factors like drought to mammalian genomes. Though epigenetic markers may be inherited, many are erased early in mammalian development.
Some researchers dispute these concerns. “Epigenetic inheritance is observed in both plants and animals,” asserts Kevin Lara, an evolutionary biologist from the University of St. Andrews. In a comprehensive study published recently, Lara and colleagues proposed a wealth of research indicating that epigenetics could play a role across the entire tree of life.
So, why is there such division in the scientific community? Timing may be a factor. “Epigenetic inheritance is an evolving area of study,” observes Lara. While epigenetics has been recognized for decades, its relevance to evolutionary research has only gained traction in the past 25 years, making it a complex field to assess.
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Source: www.newscientist.com
