Researchers studied three chickens that appeared to be literally half-male and half-female, and found that nearly every cell in their bodies — from wattle to toe — has an inherent sex identity. This cell-by-cell sex orientation contrasts sharply with the situation in mammals, in which organism-wide sex identity is established through hormones.
The confused fowl have upended a century-old rule, established for vertebrates, that all cells in an embryo start off sexually indifferent and remain so until a sex-determining gene directs the development of gonads into either ovaries or testes. The work appears in today’s Nature, and may trigger a rethink of the evolution of sex determination.
So sex determination in chickens is completely different than in mammals. Rather than evolution providing the underlying model allowing us to interpolate and extrapolate our observations, it needs to be explained away.
Gynandromorphs are striking because nothing like them has been seen in mammals. In almost all mammals, including humans, embryonic cells are initially sexually indistinguishable. During development, genetic factors trigger the formation of male or female gonads according to an animal's combination of sex chromosomes (XY for males and XX for females). The gonads then secrete hormones that direct other cells to develop as a certain sex.
“We assumed that sex determination in birds would follow the mammal pattern,” Clinton says. Accordingly, the researchers thought that one side of the gynandromorphs would be a normal female (or male) and that the other side would have a some kind of chromosomal anomaly. …
Clinton says the work shows that chickens have a fundamentally different way of determining their sex from mammals: “Hormones do play some role, but nowhere near the extent seen in mammals.”
Naturally the evolutionists assumed that sex determination in birds would follow the mammal pattern. But once again, they were wrong. Instead of evolution explaining the data, it is the data that explain evolution. With each new finding, evolution needs a new special case patched on.
Birds aren’t the only exception to the rule. The mammal model also fails with some marsupials and invertebrates like fruitflies. “The problem is, once people develop a hard and fast rule, it becomes the only game in town,” Clinton says. Sam’s “tubes and plumbing” would suggest there is no rule for all vertebrates.
No rule for vertebrates? So amazingly, with evolution we must believe something as fundamental as sex determination somehow takes on completely different mechanisms. Somewhere along the line, some random biological variation switched, for instance, from hormonal control to chromosomal control. Evolutionists, of course, have no idea how this actually happened. But they are absolutely positive it did happen. Somehow. Religion drives science, and it matters.