Free Republic

Epigenetic Study Produces 'Backwards' Human-Ape Tree by Jeffrey Tomkins, Ph.D. * A recently published study in the epigenetic modification of DNA regions similar among humans and three different apes not only provided a completely mixed up picture of evolution, but one that was entirely backwards.1 Epigenetic modifications are chemical tags that are added along chromosomes in specific patterns that control how genes are expressed. At present, 12 different types of gene regulating modifications (i.e., chemical tagging) to histone proteins that package the DNA molecule are well-documented in the human genome.2 In addition to the modification of histones, the DNA molecule...

ABSTRACT Male and female homosexuality have substantial prevalence in humans. Pedigree and twin studies indicate that homosexuality has substantial heritability in both sexes, yet concordance between identical twins is low and molecular studies have failed to find associated DNA markers. This paradoxical pattern calls for an explanation. We use published data on fetal androgen signaling and gene regulation via nongenetic changes in DNA packaging (epigenetics) to develop a new model for homosexuality. reduced androgen sensitivity in XX fetuses and enhanced sensitivity in XY fetuses, and that this difference is most feasibly caused by numerous sex-specific epigenetic modifications (“epi-marks”) originating in...

Really? THE FACTS It is a basic tenet of human biology, taught in grade schools everywhere: Identical twins come from the same fertilized egg and, thus, share identical genetic profiles. But according to new research, though identical twins share very similar genes, identical they are not. The discovery opens a new understanding of why two people who hail from the same embryo can differ in phenotype, as biologists refer to a person’s physical manifestation. The new findings appear in the March issue of The American Journal of Human Genetics, in a study conducted by scientists at the University of Alabama...

ScienceDaily (Jan. 4, 2008) — A group of scientists in Princeton's Department of Ecology and Evolutionary Biology has uncovered a new biological mechanism that could provide a clearer window into a cell's inner workings. What's more, this mechanism could represent an "epigenetic" pathway -- a route that bypasses an organism's normal DNA genetic program -- for so-called Lamarckian evolution, enabling an organism to pass on to its offspring characteristics acquired during its lifetime to improve their chances for survival. Lamarckian evolution is the notion, for example, that the giraffe's long neck evolved by its continually stretching higher and higher in...

Environment can change the way our genes work Environmental factors such as stress and diet could be affecting the genes of future generations leading to increased rates of obesity, heart disease and diabetes.A study of people suffering post-traumatic stress disorder (PTSD) after the 9/11 attacks in New York made a striking discovery. The patients included mothers who were pregnant on 9/11 and found altered levels of the stress hormone cortisol in the blood of their babies. This effect was most pronounced for mothers who were in the third trimester of pregnancy suggesting events in the womb might be responsible....