I have always found facts like these (even the whole theory of embryonic recapitulation) quite fascinating, but I never saw how they served as evidence for evolution (or any other theory) or correspond to anything evolution would predict. I am not very knowledgeable about genetics, so I am asking to be educated.Young Earth Creationism ignores the fact that leg buds form in embryos of whales, that nostrils form then migrate and fuse on top of the head to form a blowhole...
Does the correspondence of these embryonic anomalies to earlier phases of the development of a given species have a logical explanation? When examining evolutionists' claims, I try to be open-minded, and, as much as possible,view evidence from the standpoint of one who believes in evolution. Even when I do so, I cannot see what there is in the theory, or in what little I know of genetics, that would predict that a creature which developed from some previous species would, for some reason, recapitulate the fetal development of the ancestral species, which no longer exists.
There are many things in this realm above my pay grade, but I would appreciate someone explaining this to me in layman's terms (which seems to be your specialty). I am assuming that the DNA of a given modern individual remains unchanged from its conception throughout its pre-natal development and lifetime. If the DNA of the modern species has mutated in such a way that the characteristics of the ancestral species were replaced, genetically, by the characteristics of the new one, why do those old traits remain in the DNA with sufficient dominance to show up in the fetal development, but not enough to be exhibited in the developed creature? It just doesn't seem to me that the mutation of the genes of one kind of creature into those of another kind would happen without sacrificing the original characteristics in the process.
If embryological development recapitulates the historical evolution of the individual, might the human embryo of a tall, blonde individual, be expected, at certain points in its pre-natal development, to bear a resemblance to his stocky, black-haired great-great-grandfather, but then lose those characteristics prior to birth? If the characteristics of recent ancestors do not temporarily appear during late development, why would the human embryo be expected exhibit fishlike stages (which are ancestrally far more remote)?
And if the embryo does go through all of its ancestral stages en route to its modern form, what is it in the known laws of genetics that cause this phenomenon, or would lead one to predict that it should happen? Does the human baby in the womb, at some point prior to birth, resemble a creature covered with body hair? Do the embryos of birds go through a stage that could be mistaken for a reptilian embryo (I'm only asking. I honestly don't know)?
If I knew enough about genetics to conclude that, even without finding confirming specimens, a geneticist would expect a creature to embryonically recapitulate its biological history and exhibit traits of former species from which it arose, it would help a great deal in allowing me to appreciate the weight of this evidence.
If creatures are designed by an intelligence, it might be impossible to predict what path and what stages an embryo might take prior to being live-born into the world. Intelligence can be whimsical—even capricious. But science is not like that. True science can make accurate predictions from what it known. Is it possible (without first examining actual embryos) for an evolutionary geneticist to predict the appearance of any given ancestral traits in an embryonic specimen? Which discovered laws of genetics make this possible? Have they ever done this?
In my understanding, embryonic recapitulation is a theory abandoned by most scientists over 80 years ago, and renounced by the likes of Stephen Jay Gould over 30 years ago. There were too many problems: e.g., the fact that the alleged "gill slits" in the human embryo proved to bear no relation to the embryonic grooves in fishes that develop into gills; that the human heart was found, in the course of gestation to develop from two chambers, to one, and then to four; by the fact that tongues exist in human babies before teeth do, while teeth are imagined to have evolved before tongues.
Perhaps none of these facts prove that one cannot find rudiments of earlier species in modern embryos, but the question that still pesters me is: What is it about laws of heredity that would cause the embryo to recapitulate early, long-defunct ancestral species?