by Joyce Arthur
first published in OASIS, Vol. 7, # 16, Fall, 1994
Vestigial organs are degenerated, ancestral body parts which either serve little or no purpose (e.g., leg bones in whales) or which have changed their function from an earlier use. Vestigial organs are strong evidence for evolution because they clearly display an ancestral heritage with other, more primitive, animals.
One very good example of vestigial organ development in humans is the embroyonic excretory system. The human fetus grows, then discards TWO primitive kidney designs before developing a third and permanent design. Each pair of kidneys develops in a different place in the body and from mostly different tissues. The first and most primitive design, called the pronephros, forms in a rudimentary way, near the front of the body. It is the same kidney that becomes functional in some fishes. After a short time, it disappears and is replaced by the second design, the mesonephros, which develops further back, and is found in higher fishes and amphibians. As it degenerates, parts of it become modified for use by the genitals. Birds and mammals go on to develop the third kidney design, the metanephros, which forms near the back of the body.
The first two kidney designs play only an epigenetic function, at most. That is, each kidney design may in some way trigger the development of the next. Neither of the early kidneys actually do any kidney-related work.
These successive kidney designs are easily explained by evolution as the remnants of our ancestral relationship to fish and amphibians. But why in heaven would a creator need to tinker around with fish and amphibian kidneys in order to create the human kidney? We would really like to know.