Terry,
Not at all simple, as you say.
I think some people have been using some of these new findings to dispute evolution theory (it "shows" Darwin was wrong).
Read up to be prepared!
Anyway, I finished those links (not all of wiki, but...).
Regarding your post above:
Discover wrote:
"The methyl molecules have the greatest impact during periods of rapid cell division, such as when an embryo is only a few cells old." ["such as" other times too...and lesser "impact" at slower times too]
Terry, I ran across this above in the Discover article, but it wasn't referring to the same "critical period" that the other article was referring to:
"the major exposure sensitive period detected in the paternal grandmother was when she was a fetus/infant. With respect to the paternal grandmother's SGP, it is perhaps relevant that recent evidence from mice show that oogenesis continues after birth."
For other parameters that they looked at, it was ages 7 & 9 where epigenetic effects were noted to "originate."
...some dramatic statements:
"The clear pattern of specific, limited 'exposure-sensitive' periods throughout the paternal grandparents' development from conception to adulthood (Figure 1a), including a switch in the direction of the transgenerational association during the SGP (slow-growth period), confirms the importance of the SGP and suggests the existence of an evolved transgenerational response mechanism."
"In rats paternal dexamethasone exposure in utero led to both a reduced birth weight and increased hepatic activity of the gluconeogenic enzyme, phosphoenolpyruvate carboxykinase, in future offspring.[19] Beyond studies of mutagenic agents,[20] we are not aware of any general male-line transgenerational studies in humans. This probably stems from two factors; residual scepticism[21] about the germline's susceptibility to environmentally-induced change and epigenetic inheritance (with its hint of Lamarkism), and the fact that human transgenerational studies are fraught with problems."
"However, the coherence ... supports the hypothesis that there is a general mechanism for transmitting information about the ancestral environment down the male line."
...and other stuff for the female line.
"Our findings add a new, multigenerational dimension to the interplay between inheritance and environment in health and development; they provide proof of principle that sex-specific, male-line transgenerational effects exist in humans. We propose that our results, which are specific enough to allow replication, are manifestations of an evolved adaptive transgenerational response mechanism. Our study exemplifies a research approach that could, potentially, make a major contribution to public health and impact on the way we view our responsibilities towards future generations."
...and many of the titles, in the list of References at the end of the article, look like a magical journey themselves!
~Samwik
