Showing posts from April, 2014

The Trouble with Epigenetics, Part 3 – over-fitting the noise

The idea of transgenerational epigenetic inheritance of acquired behaviors is in the news again, this time thanks to a new paper in Nature Neuroscience (who seem to have a liking for this sort of thing). The paper is provocatively titled:   “ Implication of sperm RNAs in transgenerational inheritance of the effects of early trauma in mice ”. The abstract claims that: “ We found that traumatic stress in early life altered mouse microRNA (miRNA) expression, and behavioral and metabolic responses in the progeny. Injection of sperm RNAs from traumatized males into fertilized wild-type oocytes reproduced the behavioral and metabolic alterations in the resulting offspring.” Unfortunately, the paper provides no evidence to back up those extraordinary claims. It is, regrettably, a prime example of over-fitting the noise. That is, finding patterns in a mass of messy data, like faces in clouds, and building hypotheses on them after the fact. If any change i