Why would there even be an epigenome? What's the point in creating genes, just to shut them down? And why pass these markers onto subsequent generations? Can anyone explain this?

http://en.wikipedia.org/wiki/Epigenome#Functions_and_consequences

Allows more rapid physiological response to environmental shift. Think about it as an additional adaptation at the level of the gene itself - the ecological "off switch".

Say you have a gene "for" something - A causes 10 units of response in a good environment, 0 otherwise; a causes 5 units uniformly. Now say the environment suddenly prefers 0 units. All the AA genotypes are going to be able to survive, but not the aa genotypes or the Aa genotypes (since a is still producing 5 units; a funny kind of qualitative dominance).

vot?

But that does not explain why epigenetic markers are passed on to subsequent generations. How do the markers know what the environmental circumstances of a third generation offspring are going to be?

The success of that response must have led to proliferation of the genes that code for such a response.

But why would the response skip a generation?

But that does not explain why epigenetic markers are passed on to subsequent generations. How do the markers know what the environmental circumstances of a third generation offspring are going to be?

They don't "know". But if the environment is prone to shifts, then the proliferation of such genes is likely - generation skipping might also match the sequence in environmental change. The ecological structure should also be investigated.

When you say "marker", I assume you mean an allele at a quantitative gene?

I don't know if it's an allele. I just saw a Nova special called, "Ghost in our Genes". It explained epigenomes, which I never knew about. It was a fascinating program, which displayed the power of markers to turn genes on and off. It also has disturbing implications, such as is it possible to create a chemical that produces markers that would make genes turn off and give you a dread disease. The possibilities for chemical warfare are frightening.

But why would the response skip a generation?

The success of that response must have led to proliferation of the genes that code for such a response. Either that, or it's an unintended consequence of some other response, perhaps an increase in the ability to survive a famine also has bad side effects.

I don't know if it's an allele. I just saw a Nova special called, "Ghost in our Genes". It explained epigenomes, which I never knew about. It was a fascinating program, which displayed the power of markers to turn genes on and off. It also has disturbing implications, such as is it possible to create a chemical that produces markers that would make genes turn off and give you a dread disease. The possibilities for chemical warfare are frightening.

Well, I suppose. But consider this: chemical warfare can just kill you anyway. No need to bother with DNA inactivation.

But is might be easier to produce and handle DNA inactivation chemicals.

Like pesticides? We are doing this to ourselves it seems.

I disagree. I think delivery and absorbance of regular nerve agents would be easier; it has a long history of experience and handling too. I can't believe that one would want DNA deactivation when a few micrograms of nerve agent would do the job. Who was it advancing the chemical warfare option?

But couldn't diseases caused by shutting off genes be potentially more psychologically frightening than nerve agents? "I'll screw you and all your progeny!"

I don't think so. I think just killing people would be easier. But: meh.

What about having a penis? How can that be advantageous? It hangs there. If you have a bit of an accident it tears off. If you stick it in a turd you get an infection. etc.

Well, the obvious advantage of the penis is to the female, duh.

Well, the obvious advantage of the penis is to the female, duh.

obviously not. without a penis she wouldn't need a vagina.

But, she wouldn't have any kids - like yourself. Or did you come out of a test tube?

But, she wouldn't have any kids - like yourself. Or did you come out of a test tube?

you seem to be forgetting that having no penis is the default state for an animal.

So, are you for or against penises?

So, are you for or against penises?

are you for or against epigenetics?

Epigenetics is a fact. I can't be for or against it.

penis is a fact.

So, are you for or against penises?

are you for or against epigenetics?

You seem like you like penises.

I did study the development of the penis for a year on a research level, and I can safely say that I like teeth better.

Oral Surgeon?

I'm a real doctor.

I disagree. I think delivery and absorbance of regular nerve agents would be easier; it has a long history of experience and handling too. I can't believe that one would want DNA deactivation when a few micrograms of nerve agent would do the job. Who was it advancing the chemical warfare option?

Or loading rotting cow carcasses on trebuchets.

Haha, Milan, how do you like the Plague!

Epigenome.
Definition: Place where pigeons live.

So we're all cool with epigenome?