Here’s a cute one. How do you get animals with a special substance in one part of their body, but not anyplace else? You start with ancestors that had it everyplace else but that part! Sounds like a joke? Take a look at “Fish scales to fangs: Surprising tale of how teeth got their bite” – the Yahoo version of a Reuters report By Will Dunham, September 23, 2015.
According to that report, “enamel did not originate in the teeth but in the scales of ancient fish that lived more than 400 million years ago.” Ah, the wonders ordinary natural processes are supposed to work if given mind-boggling amounts of time! Oh, hmm, wait a minute, where did the ancient fish get all that enamel all over its body? Funny, I can’t seem to find anything about that. According to the standard dating, one of the oldest fish, Haikouichthys, which “somewhat resembles the…larva of modern lampreys” showed up with the rest of the major phyla of multi-cellular living things in the Cambrian “explosion” less than 200 million years before (see “Head and backbone of the Early Cambrian vertebrate Haikouichthys,” by Shu et al., Nature 421, 526 – 529 (2003)). Apparently there’s no series of fossils showing fish gradually acquiring scales and evolving this super-hard material (“the hardest tissue produced in the bodies of people and other vertebrates”). For that matter, as far as I’ve been able to dig up information on the star of this new report, Psarolepis, nothing much has been found of it beyond the head and spines in front of the first fins. The other fish mentioned, Andreolepis, seems to be known only from the scales and parts of the jaws and skull.
Well, never mind the unmentioned mystery that came before, what do they say about the switch from enameled scales to enameled teeth? Not a lot. “Only millions of years later through evolutionary processes did fish exploit the enamel to make teeth harder and stronger.” It sounds like the fish were clever enough to use the magic of “evolutionary processes” and Poof! scales without enamel and teeth with them. Perhaps this is just poor reporting. The real story would be that somewhere along the line, a mutation lead to teeth with enamel, and then another mutation caused the loss of enamel on the scales. Sounds simple enough, but just what would it take to get just the right mutations? Might it take more than two? The second one sounds especially easy, even likely, but a simple loss of the scale-enameling gene might have other consequences that would be fatal or harmful enough to cause quick elimination through natural selection. See the “News to Know” article that appeared earlier on the Answers in Genesis website, “How Did We Get Our Teeth?” concerning an earlier report on the scaly-toothed extinct fish Romundina.
Besides the two fossil fish with enameled scales, the other evidence cited in support of this imaginary account of accidental beneficiary part-swapping is the discovery that living garfish, which have thick scales “covered by a shiny enamel-like substance” called ganoine and genes for enamel, “showing that this substance really is a kind of enamel.” Wow, what a surprise, scales with enamel require genes for enamel. Oh, yes, it must be because we had a common ancestor and we got the enamel for our teeth from its scales. Sure. Sorry, I’m not buying it. The fossil record doesn’t actually show it happening, and the complexity of living things argues against such significant changes occurring by a series of mutations.
For those who find some sort of honor or even spirituality in thinking we are made of stardust, of course it only figures that the incredible chance conjunction that first put a living thing together from that shrapnel of cosmic disasters was followed by an incredible series of happy accidents gradually producing, one after another, all the lines of everything that ever lived. If “we are stardust” then we are also colonies of specialized one-celled microbes, and fish, and amphibians, mammal-like reptiles, as well as being mammals and primates in the ancestral sense and not simply due to shared physical traits. I’d believe it myself if I believed there was “overwhelming” evidence, but the evidence I’ve seen is more consistent with purposeful design of different things using similar modules or themes.
“Fish scales to fangs: Surprising tale of how teeth got their bite,” Reuters, by Will Dunham, September 23, 2015
“New genomic and fossil data illuminate the origin of enamel”
Qingming Qu, Tatjana Haitina, Min Zhu & Per Erik Ahlberg, Nature (2015) doi:10.1038/nature15259, Published online 23 September 2015
“Human Tooth Enamel Originated In Ancient Fish Scales, Researchers Say” By Samantha Mathewson Sep 25, 2015
“How Did We Get Our Teeth?”
News to Know
by Dr. Elizabeth Mitchell on August 10, 2015
“Head and backbone of the Early Cambrian vertebrate Haikouichthys”
D.-G. SHU et al., 30 January 2003, Nature 421, 526 – 529 (2003); doi:10.1038/nature01264