Time-lapse photos of a human embryonic face taking shape—unlike Haeckel’s fraudulent woodcuts—are authentic. The video accompanying “Anatomical clues to human evolution from fish,” is carefully crafted from “high quality scans . . . provided by universities and hospitals.” But not even those assembled photos can peer back through time to prove that each of us retraced our evolutionary past in the womb. Yet Dr. Michael Mosley claims that the evidence “that humans have evolved from fish” can be found “within our own bodies.”
At the time of fertilization, a new human being consists of one cell with a full complement of human chromosomes. Those chromosomes contain the blueprint to guide embryonic development. God designed the plan present in the chromosomes when He “at the beginning made them male and female” (Matthew 19:4), and He already sees us as humans when we are “yet unformed” (Psalm 139:16).
As embryonic cells multiply and differentiate, they form a flat sandwich. Neural plate cells on top of the sandwich pinch up a little pleat called the neural tube; it will become the brain and spinal cord. Then the whole sandwich rolls itself into a tube. The tube folds longitudinally and transversely, pinching off some sections and twisting others, like a precisely choreographed organic origami. Along the way, several tubes are formed. And at just the right times, various sections of these tubes are supposed to zip themselves closed. Failure to do so can result in birth defects such as cleft palate, anencephaly, spina bifida, and heart defects.
Vertebrate embryos all utilize the roll-into-a-tube method of construction. But the earliest embryonic development in fish differs markedly from that in mammals. Soon after fertilization, the embryo becomes a ball of cells, called a blastula in fish but a blastocyst in mammals because of these differences. Later, most fish hollow out a neural tube, but mammals make one by folding up a pleat.
Eyes on the side
Dr. Mosley’s video sequence makes us feel like we’re seeing a wall-eyed fish transform into a human face. Could there be a design advantage explaining why God puts human eyes on the sides and then moves them? Indeed there is. A spot on the neural plate is destined to become eyes. It divides into two optic vesicles. When the neural tube forms, these optic vesicles are pushed up against some ectodermal cells on the surface. Each optic vesicle signals the ectodermal cells it touches to differentiate into a lens. Then the new lenses tell the optic vesicles to grow the rest of the eye parts.
Thus, the eyes form with plenty of space in between to give the middle of the face and the front of the brain room to develop. In fact, a tragic birth defect in which the eyes are fused is associated with a severely underdeveloped forebrain and nose. Most of the video clip is spent showing the nose. Several bulges of cells develop into the parts of the face, nose, and mouth. The face zips itself up after the parts roll into place. Fusion of the face in the middle is important for eating and speaking. Failure of fusion results in cleft lip or cleft palate.
“Gill-like structures,” homologues, and Haeckel
“Gill-like structures” are another bit of fishy evidence Dr. Mosley seeks to feed us. The poorly-named “gill slits” in human embryos are not anything at all like gills and are not even slits, just folds of tissue destined to develop into various anatomical parts of the head and neck. They never have a function or a structure remotely resembling gills (see Something Fishy About Gill Slits!). They don’t even turn into anything having to do with the lungs. In fact, the video shows what some of them become: parts of the face!
Evolutionists point to sequential homologies in fish gills, fish jaws, reptilian jaws, and mammalian ear bones. Homologues are similar embryonic structures, such as Meckel’s cartilage, which have different destinies in different kinds of creatures. Meckel’s cartilage supports the gills in cartilaginous fish. It ossifies to form the jaws of bony fish and reptiles. And in mammalian embryos Meckel’s cartilage helps shape the middle ear bones and the mandible; then it disappears. But each creature has its own kind of DNA directing the process, and at no time in science do we see DNA of one creature mutating to produce new information that can change the organism into a new kind. Homologies are consistent with a common Designer. In fact, not all apparent homologies match up with evolutionary expectations. See Natural Selection vs. Evolution to learn more.
So far Dr. Mosley’s case has rested on superficial similarities. We’ve already pointed out that the DNA is different and that even the cellular arrangement is different from the beginning. But what about Haeckel’s work? Even though it has long been discredited, subsequent efforts have at times claimed to substantiate his findings. However, these efforts have suffered from an inadequate sampling of organisms. A more recent study conducted by scientists who do accept evolution was designed to set the record straight. Examining a large variety of vertebrate embryos, they found “considerable variability” at the very stage where Haeckel’s legacy has proclaimed them to be “virtually identical.”1
Gonads go where?
Next, Dr. Mosley tries to convince us of our fishy ancestry by telling us that sharks keep their gonads (ovaries and testes) tucked behind the liver but that human evolution completed the process by having them descend. Indeed, our ovaries and testes do form inside the abdomen. In fact, the primordial germ cells destined to become eggs or sperm are formed outside the embryo’s body and must migrate to the gonads while they are still nearby, in the abdomen. As the embryo grows, those structures are simply dragged lower in the body. Finally, in males, under hormonal influence they descend to their optimal position outside the body, the cooler temperature there being essential for fertility.
Human gonads illustrate that temporary resemblance is not evidence for ancestry. A child’s gender is determined at the moment of fertilization by the DNA. Buts the gonads—like the rest of the urogenital structures—are indistinguishable until the seventh week. Male and female gonads use the same template and then take on distinct gender differences. Nevertheless, at no point in development can the embryo be thought of as sex-less. The male does not turn into female, nor vice versa. Human gender is in the genes from the moment of fertilization. Likewise, fish have fish DNA and humans have human DNA. Temporary superficial resemblances are irrelevant. One never turned into the other.
If we, as mere human beings, can use the same inventions for multiple uses, should it surprise us that God used His good ideas in a variety of ways? When we see common designs, our worldview determines whether we shout common Designer or common ancestor.
God designed logical approaches to embryonic construction. One common feature in vertebrate development is a flat disc rolling into a tube which twists until the desired shape is achieved. Another is having the gonads develop near the germ cell supply and then moving them later if appropriate. Another is the use of similar embryonic templates—homologues—destined to be shaped into different structures. Yet in each kind of organism the blueprint is specified in the DNA, and the DNA in humans is human DNA, not fish DNA. Fish DNA guides the formation of fish, not primordial humans. Thanks to the DNA, it is irrelevant that human embryonic eyes “start out on the sides of your head, but then move to the middle.”
Finally, the hiccup is offered as evidence of ancient tadpoles in our family tree. Tadpoles have a reflex which keeps their lungs open to air but closed to water, diverting water toward the gills. The human hiccup starts with a muscle spasm in the diaphragm and continues when a reflex causes the vocal cords to slam shut. During human fetal development, the motor nerves needed for this reflex are formed before the nerves used for breathing. Therefore, on the basis of this loose analogy, a Canadian group suggested2 that the vocal cord reflex in humans is essentially the same as the tadpole’s reflex, even responding to the same chemical signals. That supposedly makes the development of human lungs the next evolutionary step, leaving the hiccup reflex of “no value” except as “another bit of evidence of our common ancestry.”
God did not invent a whole new kind of biochemistry for each kind of organism. There are many molecules that show up in multiple creatures. The same Creator created fish, tadpoles, and humans. Therefore, it should come as no surprise to learn that both the tadpole reflex and the human hiccup reflex can be inhibited by high carbon dioxide levels and by the same neuroreceptor antagonist.2 Besides, contrary to Dr. Mosley’s opinion, the reflex slamming shut of the vocal cords is not a useless vestigial feature: it is the fail-safe to keep you from aspirating liquids into your lungs when those liquids slip past your epiglottis!
Identity is more than skin deep: It’s in the DNA
Humans are humans because they have human DNA. Human DNA has always directed the entire process of human embryologic formation. Ancestral fish DNA had no way to acquire information to become human. Furthermore, common design does not prove common ancestry. The Bible (1 Corinthians 15:39) says, “All flesh is not the same flesh, but there is one kind of flesh of men, another flesh of animals, another of fish, and another of birds.” Common design is consistent with a common Designer who created organisms to reproduce after their kind, not to transform from one kind into another.