In a study published Friday in the journal Science Advances, Milinkovitch and his grad student, Nicolas Di-Po, report that the mutated gene that robbed the bearded dragon of its scales is the same gene that controls feather development in birds and fur in mammals. Although the three features look very different in adult animals, they start in the same place...
In a study published Friday in the journal Science Advances, Milinkovitch and his grad student, Nicolas Di-Po, report that the mutated gene that robbed the bearded dragon of its scales is the same gene that controls feather development in birds and fur in mammals. Although the three features look very different in adult animals, they start in the same place...
Early on in embryonic development, feathers and fur look startlingly similar – both begin as tiny, thick accumulations of cells on the skin known as anatomical placodes. This shared morphology indicates that the features have the same evolutionary roots, which would seem to make sense, since birds and mammals evolved from a common ancestor some 320 million years ago.
But that ancestor was also the predecessor of modern reptiles; in fact, reptiles and birds are far more closely related than birds and mammals. Yet reptile scales develop very differently than feathers and fur – or they seemed to, at any rate. Not a lot of scientists study reptile embryos, Milinkovitch noted ("model species" like fruit flies and mice tend to get most of the attention), but those who did generally couldn't find evidence of anatomical placodes...
That's where things stood when Di-Po began parsing the genome of the naked bearded dragon his adviser had brought back to the lab. He pinpointed the mutation that prevented scales from developing, only to discover that it was EDA – the same gene responsible for feathers and fur.
That prompted the duo to take a closer look at the embryos of normal bearded dragons during development. They realized that the tiny creatures did have anatomical placodes, they just appeared and dispersed differently than the versions biologists are accustomed to seeing in mammals and birds...
Eventually, he and Di-Po identified placodes in several species of snake, lizard and crocodile.
"They obviously inherited this from a common ancestor," Milinkovitch said.
"That makes sense, ecologically speaking, when you think about, 'what is the innovation of amniotes?' " he continued, using the term to describe creatures like reptiles, birds and mammals, whose fetuses develop in membrane-bound amniotic sac that allows their mothers to lay fertilized eggs on land (or nurture them inside the uterus, as most mammals do).
Unlike amphibians and lobe-finned fish, amniotes aren't anchored to water by the need to lay their eggs there. That meant it was worth investing in adaptations that allowed us to live entirely terrestrial lives, like skin or scales that keep us from drying out. Hundreds of millions of years after reptiles, birds, and mammals diverged from this original amniote, we are united by the outcomes of this innovation. "They are extremely different morphologically, but if you look past that you can see the homology," Milinkovitch said. "That's the beauty of it."
So the same gene will share the same functions across different kinds of creatures and produce very different results. We have seen this occur across many different creatures before,
so why this discovery is considered as some sort of breakthrough is beyond me. In contrast, we have also observed entirely different genes produce similar results in entirely different creatures, as well as genes that are similar between different creatures that produce entirely different results. Despite this, t
his somehow is still evidence of common ancestry? This non-sense of phylogenetic homology is akin to convergent evolution, which is nothing more than an excuse given by the proponents of naturalism for the lack of evidence for common ancestry due to such factors as environmental differences.
This article is a shining example that their conclusions are based on philosophical grounds just as much as those for the intelligent design argument.
If its true that this occurred by evolutionary means, if phylogenetic homology is true, we would see some consistency between the genes that performs these functions between creatures to begin with, which we don't, nor do we see any actual addition of genetic information for evolution to occur in the first place. We only observe the removal of genes, reduplication of genes, or the increased amounts of the same information, but nothing new. So therefore, there logically has to be a cause beyond simple genetics, beyond simple naturalistic explanations as to why this is occurring. The intelligent design argument is the most viable assertion, particularity that of Christianity, which states that different creatures have similar features because of causality and intent that is of a supernatural origin, and nothing at all to do with
common ancestry through chance mutations that results in modifications to the morphology of a creature over time. The only thing this article proves is how little they know about how life truly came about, and how foolish they make themselves look every time they boast of "new" evidence that is circumstantial at best as if its prima facie evidence of evolution.
