Women and men, in accordance with popular self-help publications, hail from various planets, but exactly what actually separates them are radically various chromosomes. With two Xs you are a lady; with one X and a small y, you’re male. No other set of chromosomes is almost because diverse. just How did the intercourse chromosomes become therefore dissimilar?
When you look at the October 29, 1999 dilemma of Science, Bruce Lahn, PhD, assistant teacher of individual genetics at the University of Chicago and specialist in the evolution associated with intercourse chromosomes, along side their colleague David Page, MD, of this Whitehead Institute, report that the X and Y chromosomes–which arose from a set of identical, non sex-determining chromosomes (referred to as autosomes)–diverged from one another during the period of about 300 million years by dealing with four discrete phases in the place of in a transition that is smooth.
«By fossil digging regarding the intercourse chromosomes, we had been in a position to reconstruct the four events that drove intercourse chromosomes within their distinctive X and Y kinds and up to now whenever these events happened during development,» claims Lahn. » The back that is farther time we look, the more comparable X and Y appear, boosting the idea which they arose from a couple of identical autosomes.»
Intercourse wasn’t constantly decided by DNA. In lots of reptiles, the heat at which the eggs are incubated determines the sex of this offspring. Sigue leyendo