by Sue Lange
I was inspired a while back by the challenge in sfsignal.com to science fiction writers to work with current science. Even though Anthena Andreadis was talking about science fiction, it gave me an idea for this non-fiction-about-science series of blog posts. I picked one of the topics she mentioned: epigenetics. It’s weird and appropriate.
In a nutshell epigenetic traits are changes in gene expression (what something looks like for instance) that have not occurred through changes in the DNA. It’s easy to see how environment affects our bodies after we’re born. We break legs, contract diseases. These things change the way our bodies look and function. What’s weird is that sometimes these changes due to environment can be passed on to offspring. Doesn’t that just fly in the face of everything you learned in Genetics 101?
As self-respecting denizens of the 21st Century, we pooh-pooh Lamarck. The Lamarckian model of evolution has the giraffe coming into being after generations of horses slowly stretched their necks through lifetimes of eating leaves higher and higher on the trees. One individual’s neck grew slightly longer in its lifetime and that slightly longer neck was passed on to the offspring whose neck also elongated slightly in their lifetime. After several lifetimes of slight neck stretches, voila! we have a long-necked horse.
How silly. Us self-respectors subscribe to Darwin and Mendel nowadays. Inherited change occurs in the genes rather than in the bodies of the gene expressors: the people. Or the animals.
But hold that thought. There is evidence afoot that we CAN inherit changes that come about due to environment acting on the phenotype rather than mutation in the DNA acting on the germ cells. We call that process Epigenetic Inheritance, and to this biology-major, college-graduate, that’s just weird.
Here’s a quick rundown of the classic example for epigenetic inheritance posted by the Institute of Science in Society:
“In the nest, the mother rat licks and grooms her pups, and while nursing, arches her back to groom and lick her pups. Some mothers (high performers) tend to do these more frequently than others (low performers). As adults, the offspring of high performers are less fearful and show more modest responses to stress in the hypothalamus-pituitary-adrenal (HPA) neuro-endocrine pathway.
Cross-fostering studies showed that the biological offspring of low-performers reared by high-performers, resemble the offspring of high performers, and vice versa. …
Amazingly, the pups of both high and low-performing mothers start out life genetically the same.”
There are other examples out and about. Children of holocaust survivors develop diseases they would not have developed had their parents not been malnourished during part of their lives. Fruit flies exposed to harsh chemicals grow bristly eyelashes (obviously these scientists are working with bodacious microscopes to be able see that) and then their younguns grow bristly eyelashes too.
When details of the methods for inheritance are explained, often I have a hard time deciding if this is something different than regular inheritance via genes. It seems to involve the DNA somehow. The difference between the two mechanisms is too subtle for me to happily accept a Lamarckian model. It begs further investigation.
Regardless, whatever is going on is certainly weird and proves once again that the more we discover, the less we know. It’s sort of a built-in feature of science that keeps us coming back for more.
Science Daily nicely illustrates this weirdness that is scientific study generally and epigenetics specifically in the title of their 2009 article, “100 Reasons to Change the Way We Think About Genetics.”
Sue Lange’s latest ebook, Tritcheon Hash, is full of lapses of logic and weird science. Sample the book right here at BVC.