Linda and our friends John and Joan McManus
Catalina Island
Last November I wrote a blog
called “Grandma’s Curse”. The gist
of that little essay was that cancer researchers had discovered that
“epigenetic” factors appeared to conspire somehow to allow mice to inherit
bodily changes inflicted on their grand-parent mice – in complete contradiction
to Francis Crick’s “Central Dogma”, which states that characteristics acquired
by a person (or mouse) during its lifetime cannot flow back into the genome and
become heritable. In other words,
according to Crick, Lamarck was
completely wrong about how evolution occurs, and Darwin was completely right. I said at the time that I didn’t
understand “epigenesis”. I still
don’t.
Now, however, epigenesis is
getting to be a hot topic. For
example, there is an article in the magazine “The Week” entitled “The
‘switches’ on your genes", and
subtitled “New research suggests that people’s experiences, not just their
genes, can effect the biological legacy of their offspring.” In other words, Lamarck was right – at
least partially. The same article
defines “epigenetic” as “on top of genetics”, and goes on to say that it concerns
the molecular “switches” that tell the various genes when to be “expressed “ –
that is, when to do their job by making proteins. I gather from this article that life experiences,
environment, etc., can affect these “switches” – and somehow the altered
switches themselves can be inherited.
Really: I don’t get it, and
I would sleep better at night if somebody would enlighten me. In a nutshell, here is what I don’t
understand”
What in heck are these
“switches”, anyway? Are they
proteins? They must be some kind
of organic molecule, that’s for sure.
If they can be inherited, doesn’t it follow that they somehow are coded
for in the DNA? If they can be
altered by environmental factors and/or life experiences – and inherited –
then, it would seem, our experiences can alter our DNA. Was Lamarck right after all?
I should have stuck with
plate tectonics.
Seeing pictures of Linda that I haven't seen before stops my heart for a second. Myrl, if you are confused by The Week's article, imagine how non-scientific people like me feel. You are doing a great job at conveying this information. There seem to be so many angles that researchers are taking to improve cancer detection, treatments, and cures. I applaud them all.
ReplyDeleteI love this topic. Fascinating stuff. Epigenetic factors could probably be proteins, but probably the most well-known one is DNA methylation - which is just adding a methyl group to the DNA. This alters its expression. There could be environmental factors that alter methylation, or some other epigenetic factors. Methylation patterns are inheritable, so if something alters them, it will be passed on. I don't know that much about this but isn't it fascinating!!!!!!!!!! For more info on methylation, wikipedia has a pretty good explanation: http://en.wikipedia.org/wiki/DNA_methylation.
ReplyDeleteI have to wonder about things like PTSD - could extreme stress alter methylation patterns? I wouldn't be surprised. I also suspect that epigenetic factors play a role in instinct - there are some amazing instinctive behaviors of animals, and you have to wonder how they know to do what they do, having never been exposed to the situation before. Just my thoughts - I have no idea if there's any research linking epigenetic factors to either of these things.