Epigenetics May Become "Evolution Heresy" - Evolution News & Views

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Epigenetics May Become "Evolution Heresy"

Neo-Darwinism relies on mutation and selection, but selection of what? Epigenetics is confusing the target of selection, raising fears of neo-Lamarckism.

Elizabeth Pennisi in Science Magazine reports that ongoing studies of epigenetic inheritance at the University of Groningen in the Netherlands have evolutionists worried. Frank Johannes and his team have apparently shown that methylation marks on the DNA of plants can alter the phenotype in heritable ways that remain stable up to at least eight generations.

For some evolutionary biologists, just hearing the term epigenetics raises hackles. They balk at suggestions that something other than changes in DNA sequences -- such as the chemical addition of methyl groups to DNA or other so-called epigenetic modifications -- has a role in evolution. All of which guarantees that a provocative study presented at an evolutionary biology meeting here last month will get close scrutiny. It found that heritable changes in plant flowering time and other traits were the result of epigenetics alone, unaided by any sequence changes. (Emphasis added.)

Her title, "Evolution Heresy? Epigenetics Underlies Heritable Plant Traits," reflects the religious wars these findings threaten to ignite. The concern is that the environment -- not chance mutations -- can cause adaptive epigenetic changes directly. If a plant or animal acquires characteristics during its lifetime that are heritable, the specter of long-dead Lamarckism rises once again to haunt evolutionary biology.

But the experiment doesn't address the most controversial aspect of epigenetics and evolution -- whether an environmental stress can alter an organism's epigenetic markings and lead to a permanent trait change that's acted upon by natural selection -- a notion that, to some, sounds suspiciously like Lamarckism.

So it's not just a matter of displacing natural selection to act on epigenetic marks instead of, or in addition to, genetic mutations. The issue is the possibility of a built-in adaptability that allows organisms to respond to environmental changes. It calls into question whether variation (mutation) is unguided. That's an entrenched paradigm that will be hard to change:

"A lot more hard evidence is necessary before one can claim that epigenetics plays a very important role in evolution," says ecological geneticist Koen Verhoeven at the Netherlands Institute of Ecology in Wageningen. And, Richards adds, "people are really stubborn about accepting that that's possible."

You'd hope that people who are biologists would not be "stubborn," but rather would seek to follow the evidence where it leads.

What does this mean for the theory of intelligent design? It's too early to say. If experiments continue to support epigenetic inheritance, additional research questions will arise. Do the epigenetic marks ever become encoded in the DNA sequence, or are they temporary? Are epigenetic marks subject to natural selection? What directs the methylation activity? It might prove to be a built-in adaptability that provides robustness in a changing world. If so, it would require higher orders of complex specified information than the genetic code, because it suggests foresight to handle contingencies.

However it turns out, the issue about epigenetic inheritance in evolution is sure to be interesting. What's also interesting is watching how the neo-Darwinian old guard, biology's ancien régime, responds to heresy in the ranks.