Creative design in the human embryo
Posted on homepage: 18 June 2014 (GMT+10)
One of the most marvellous evidences of creative design and organisation is the astonishing process of how a human being develops in their mother’s womb. But right at this point, evolutionists come on with one of their strongest arguments. They say, in effect, “Look, if you’re talking about creation, then surely the Creator must not be very good at it, or else there wouldn’t be all those mistakes in human embryonic development.”
Figure 1 shows an early stage in human development. Consider it your first “baby picture”. You start off as a little, round ball of “unformed substance”. Then gradually arms, legs, eyes, and all your other parts appear.
At one month, you’re not quite as charming as you’re going to be, and here’s where the evolutionist says, “There’s no evidence of creation in the human embryo. Otherwise, why would a human being have a yolk sac like a chicken does and a tail like a lizard does? Why would a human being have gill slits like a fish does? An intelligent Creator should have known that human beings don’t need those things.” Well, there they are, “yolk sac, gill slits, and a tail.” Why are they there?
What’s a creationist going to say?
The evolutionist believes these structures are there only as useless leftovers, or “vestiges” of our evolutionary ancestry—remainders of the times when our ancestors were only fish and reptiles. Actually, the evolutionary idea of vestigial organs slowed down scientific research for many years. If you believe something is a useless, non-functional leftover of evolution, then you don’t bother to find out what it does.
Fortunately, other scientists didn’t take that view. They felt instead that such structures probably had a function important for human development.
Sure enough, studies have shown that at least 178 of 180 organs once listed as evolutionary vestiges have quite important functions in human beings. Take the yolk sac, for instance. In chickens, the yolk contains much of the food that the chick depends on for growth.
But we, on the other hand, grow attached to our mothers and they nourish us. Does that mean the yolk sac can be cut off from the human embryo because it isn’t needed? Not at all.
The so-called “yolk sac” is the source of the human embryo’s first blood cells, and death would result without it. Now here’s an engineering problem for you. In the adult, you want to have the blood cells formed inside the bone marrow. That makes good sense, because the blood cells are very sensitive to radiation damage and bone would offer them some protection.
But you need blood in order to form the bone marrow that later on is going to form blood. So, where do you get the blood first?
Why not use a structure similar to the yolk sac in chickens? The DNA and protein for making it are “common stock” building materials. And, since it lies conveniently outside the embryo, it can easily be discarded after it’s served its temporary—but vital—function. Notice, this is exactly what we would expect as evidence of good creative design and engineering practice.
Suppose you were in the bridge-building business, and you were interviewing a couple of engineers to determine whom you wanted to hire. One fellow says, “Each bridge I build will be entirely different from all others”. Proudly he tells you “Each bridge will be made using different materials and different processes so that no one will ever be able to see any similarity between the bridges I build”.
How does that sound?
Now the next fellow comes in and says, “Well, out back in your yard I saw a supply of I-beams and various sizes of heavy bolts and cables. We can use those to span either a river or the San Francisco Bay. I can adapt the same parts and processes to meet a wide variety of needs. You’ll be able to see a theme and a variation in my bridge building, and others can see the stamp of authorship in our work.”
Which fellow would you hire?
As A.E. Wilder-Smith points out (1980), we normally recognize in human engineers the principles of creative economy and variations on a theme. That’s what we see in human embryonic development. The same kind of structure that can provide food and blood cells to a chicken embryo can be used to supply blood cells (all that’s needed) for a human embryo. Rather than reflecting time and chance, adapting similar structures to a variety of needs seems to reflect plan and purpose.
The same is true of the so-called “gill slits”.
In the human embryo at one month, there are wrinkles in the skin where the “throat pouches” grow out. Once in a while, one of these pouches will break through, and a child will be born with a small hole in the neck. That’s when we find out for sure that these structures are not gill slits. If the opening were really part of a gill, if it really were a “throw-back to the fish stage” then there would be blood vessels all around it, as if it were going to absorb oxygen from water as a gill does.
But there is no such structure. We simply don’t have the DNA instructions for forming gills.
Unfortunately, some babies are born with three eyes or one eye. That doesn’t mean, of course, that we evolved from something with one eye or three eyes. It’s simply a mistake in the normal program for human development, and it emphasizes how perfect our design features and operation must be for life to continue.
The throat (or pharyngeal) grooves and pouches, falsely called “gill slits” are not mistakes in human development. They develop into absolutely essential parts of human anatomy.
The middle-ear canals come from the second pouches, and the parathyroid and thymus glands come from the third and fourth. Without a thymus, we would lose half our immune systems. Without the parathyroids, we would be unable to regulate calcium balance and could not even survive. Another pouch, at one time thought to be vestigial by evolutionists, becomes a gland that assists in calcium balance.
Far from being useless evolutionary vestiges, then, these so-called “gill slits” are quite essential for distinctively human development.
As with yolk sacs, “gill slit” formation represents an ingenious and adaptable solution to a difficult engineering problem. How can a small, round egg cell be turned into an animal or human being with a digestive tube and various organs inside a body cavity? The answer is to have the little ball (or flat sheet in some organisms) “swallow itself”, forming a tube which then “buds off” other tubes and pouches. The anterior pituitary, lungs, urinary bladder, and parts of the liver and pancreas develop in this way. In fish, gills develop from such processes, and in human beings, the ear canals, parathyroid, and thymus glands develop. Following DNA instructions in their respective egg cells, fish and human beings each use a similar process to develop their distinctive features. (See Figure 2).
What about the “tail”? Some of you have heard that man has a “tail bone” (also called a coccyx), and that the only reason we have it is to remind us that our ancestors had tails.
You can test this idea yourself, although I don’t recommend it. If you think the coccyx is useless, fall down the stairs and land on it. (Some of you may have actually done that—unintentionally, I’m sure!) What happens? You can’t stand up; you can’t sit down; you can’t lie down; you can’t roll over. You can hardly move without pain. In one sense, the coccyx is one of the most important bones in the whole body. It’s an important point of muscle attachment required for our distinctive upright human posture (and also for defecation, but I’ll say no more about that).
So again, far from being a useless evolutionary leftover, the coccyx is quite important in human development.
True, the end of the spine sticks out noticeably in a one-month embryo, but that’s because muscles and limbs don’t develop until stimulated by the spine (see Figure 2). As the legs develop, they surround and envelop the coccyx, and it winds up inside the body. Once in a great while a child will be born with a “tail”.
But, is it really a tail?
No, it’s not even the coccyx. It doesn’t have any bones in it; it doesn’t have any nerve cord either. The nervous system starts stretched out open on the back. During development, it rises up in ridges and rolls shut. It starts to “zipper” shut in the middle first, then it zippers toward either end. Once in a while it doesn’t go far enough, and that produces a serious defect called spina bifida. Sometimes it rolls a little too far. Then the baby will be born—not with a tail, but with a fatty tumor. It’s just skin and a little fatty tissue, so the doctor can just cut it off. It’s not at all like the tail of a cat that has muscle, bones, and nerve, so cutting it off is not complicated. (So far as I know, no one claims that proves we evolved from an animal with a fatty tumor at the end of its spine.)
The details of human development are truly amazing. We really ought to stop, take a good look at each other, and congratulate each other that we turned out as well as we did!
Evolutionists used to say that human embryonic development retraced stages in our supposed evolutionary history. That idea, the now defunct “biogenetic law”, was summarized in the pithy phrase, “ontogeny recapitulates Phylogeny”. (Want to sound educated? Just memorize that phrase!) The phrase means that the development of the embryo is supposed to retrace the evolution of its group.
The fertilized egg, for example, would represent our one-celled ancestors, sort of the “amoeba stage”.
Sure enough, we start as small, round structures looking somewhat like single cells. But notice how superficial that argument is. The evolutionists were just looking at the outside appearance of the egg cell. If we look just on outside appearance, then maybe we’re related to a marble, a beebee (air-gun projectile), or a ball bearing—they’re small, round things! An evolutionist (or anyone else) would respond, of course, “That’s crazy. Those things are totally different on the inside from a human egg cell”.
But, that’s exactly the point. If you take a look on the inside, the “dot” we each start from is totally different from the first cell of every other kind of life.
A mouse, an elephant, and a human being are identical in size and shape at the moment of conception. Yet in terms of DNA and protein, right at conception each of these kinds of life is as totally different chemically as each will ever be structurally. Even by mistake, a human being can’t produce yolk or gills or a tail, because we just don’t have, and never had, those DNA instructions.
The human egg cell, furthermore, is not just human, but also a special individual. Eye color, general body size, and perhaps even temperament are already present in DNA, ready to come to visible expression.
Perhaps the most eloquent summary of embryonic development was written over 3,000 years ago by the Psalmist David (Psalm 139). He talks about his “unformed substance”, and that’s just how we all begin—as unformed substance. Then he talks about being “knit together” in his mother’s womb, and that’s similar to what we observe in embryonic development. The substance is there to start with, like yarn in a basket. And the plan is there, written out in DNA like a knitter’s plans. Instructions are creatively conceived and spelled out ahead of time. As the sleeves of a sweater take shape from yarn in the skilful knitter’s hands, so the human embryo takes shape according to the plan of his or her Creator.
We are indeed “fearfully and wonderfully made.”
- This article was reproduced in modified form from the book Creation: The Facts of Life, by permission © CLP 1980.