January 18, 2006

SAY WHAT?

Effects of diet, smoking passed to sons in DNA (Dan Box, The Australian, January 6th, 2006)

Children are more likely to be obese if their fathers started smoking before adolescence but they will live longer if their grandfathers went hungry during childhood.

The charm of the modern rationalist lies in his delusion he is rational.

Posted by Peter Burnet at January 18, 2006 7:11 PM
Comments

Since both smoking and fasting have clear effects on the functioning of the human body, why would you believe that such cannot affect gene expression in sperm production ?

Posted by: Michael Herdegen [TypeKey Profile Page] at January 18, 2006 7:37 PM

. . . and boys who begin masturbating at age 12 will have more sons than daughters. And these sons are more likely to eat carrots, hate peas, play baseball, build a treehouse in their backyard, go to college out of state, marry a blonde - I'll get back to you on other ramifications when I finish the research on this vital subject.

Posted by: obc at January 18, 2006 7:44 PM

Michael:

I was all set to take you on, but then I saw obc's comment. That will do just fine.

Posted by: Peter B at January 18, 2006 7:51 PM

Mr. Herdegen:
Not to get obscene, but you make and get rid of sperm all the time. Yes, smoking may have an effect on that particular crop of sperm but when you started smoking shouldn't have an effect. Same deal with Grampa starving. OK, I'll buy that while he was undernourished as a youth his sperm may have been off, but not still 20 years later when he got down to business storming Grandma's Siegfried Line.

Posted by: Bryan at January 18, 2006 7:52 PM

Peter B:

So, what you're saying is that you don't believe that human behavior can have any effect on future offspring ?

obc's post is obviously sarcastic, but the irony is that s/he may be more right than wrong.

Bryan:

Some behaviors permanently change biological functioning, by turning on or off genetic switches.

Women who ever smoked will ALWAYS have a 100% greater chance of being afflicted with lung cancer, even if they quit twenty years ago.

Similarly, being malnourished as a child will permanently affect that individual's biofunctioning, regardless of how much food they have access to as an adult.

Which is not to say that ALL behaviors have a hereditary effect; probably few do.
However, to say that NONE do is misguided.

Posted by: Michael Herdegen [TypeKey Profile Page] at January 18, 2006 8:13 PM

Michael:

obc's post is obviously sarcastic, but the irony is that s/he may be more right than wrong.

Yeah, well me and my buddy obc are into irony big time.

OK, seriously now. Did you notice how the story shifted from wayward fathers (indulgent and sinful) to grandfathers (victims of their times).
Any comments there? But, yes that is a digression. Of course human behaviour affects offspring. That is hardly news the world needed scientists to tell them. The issue is a political and aesthetic one. Are you into aesthetics, Michael?


Posted by: Peter B at January 18, 2006 8:31 PM

Children of immigrants are also more likely to speak better English than their parents; doesn't mean it was passed on genetically. Let's not confuse a simple correlate with a cause, nor nature with nurture.

Posted by: ras at January 18, 2006 9:21 PM

Correlations for fun and profit.

Posted by: ghostcat at January 18, 2006 9:38 PM

We're all Lamarkists now.

Posted by: David Cohen at January 18, 2006 10:18 PM

Son-of-a-gun. There really must be some group dementia that makes people go off chasing Darwinian explanations for Spencerian phenomena.

Please, please, please remember that you are not going to find genetic evolution in an organism with an 18-year generational cycle in historical time. Give me an effing break! DNA! From your grandfather's behavior!

Look. If your grandfather smoked during adolescence he exibited weak inpulse control with respect to physical, especially oral gratification. The same weakness which disposes on to smoke disposes one to overeat.

You might have inherited that weakness, a brain-chemistry dependency, which had been in your blood-line for many generations, or you might have learned the habits of intemperance as a family tradition. Either way your genes were not transformed in two generations by an act of Lysenkoist ledgerdemain.

Similarly, it is much more likely that a family tradition of privation would survive as a cultural value favoring focus and ambition, even, no, especially, if one or two intervening generations had overcome hardship.

Environmentally driven social evolution: the stern discipline which pervades all nature and which is a little cruel that it may be very kind.

Posted by: Lou Gots at January 18, 2006 10:25 PM

Did you notice how the story shifted from wayward fathers (indulgent and sinful) to grandfathers (victims of their times).

I have noted, over the years, that you are far more likely to spot such references than I am.

Whether you are oversensitive or I am merely dull-witted, I cannot say, although I note that you very often find inferences in my words that I never attempted to imply.

I attribute it up to the effects of being a cultural conservative living in Canada.

Nothing Lamarkian about the changes:

These effects are thought to be due to subtle chemical changes to DNA, known as "epigenetic" modifications, which were generally believed to be reset with each generation.
Posted by: Michael Herdegen [TypeKey Profile Page] at January 19, 2006 12:13 AM

Smells like teem spirit.

Posted by: Barry Meislin at January 19, 2006 3:20 AM

If your great-great-great-grandfather ate a lot of buffalo meat, chances are you may develop an addiction to Federal Casino Licenses.

Posted by: Noel at January 19, 2006 7:16 AM

I see. So Lamarck is responsible for the mechanism, but other people's heroes aren't?

Posted by: David Cohen at January 19, 2006 7:26 AM

Actually, this is all quite possible, and there is no need to invoke Lamarck, except as an analogy. The concept has been very well known to molecular biologists for roughly two decades, and to geneticists for roughly a century. It is called epigenetics. It involves changes in heritable traits that are not reflected in actual genetic (i.e. DNA) changes, and is transmitted by chemical modification of DNA bases (methylation) or by modification of the proteins (histones) that package DNA in cells. These modifications - which, it is worth repeating, are distinct from actual DNA mutations - can still be inherited.

The process, at least as it is (probably) being invoked in this article, has little to do with Darwinian evolution.

Posted by: M. Bulger at January 19, 2006 12:36 PM

M:

That's the point.

Posted by: oj at January 19, 2006 1:34 PM

Little to do, that is, in the positive or negative sense.

Posted by: M. Bulger at January 19, 2006 5:29 PM
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