Systematics and Evolution 135Creationists demand just one transitional fossil. When you give it to them, they then
claim there is a gap between these two fossils and ask you to present a transitional
form between these two. If you do, there are now two more gaps in the fossil record,
and so on ad infinitum. Simply pointing this out refutes the argument. You can do it
with cups on a table, showing how each time the gap is filled with a cup it creates two
gaps, which when each is filled with a cup creates four gaps, and so on. The absurdity
of the argument is visually striking.A good analogy of how creationists abuse the evidence before them and refuse to see the
obvious connections between transitional fossils is lampooned in a number of clever edito-
rial cartoons. One cartoon displays the word EVOL_T_ON on the board. One character says,
“That can’t possibly spell evolution! There are too many gaps!” The other replies, “That must
mean the answer to the puzzle is ‘CREATION.’ ” Another cartoon shows the sequence of
hominid fossils with a couple of question marks scattered among the individual specimens.
The caption reads, “If yu cn rea ths, don’ gme tht bulsit abut missng transitional forms in
th evolutnry t ee!” Most people are capable of filling in the blanks and seeing patterns and
connections, but creationists doggedly refuse to accept any evidence presented to them, no
matter how clearcut.
Another analogy about seeing connections in transitional fossils is to imagine looking
down on a bridge over a river. We can see the water flowing beneath it at one end, and the
water flowing out the other side, but we can't actually see that the two bodies of water are
connected if we are only looking down on the bridge. Our mind fills in that connection for
us. The creationist refusal to see the connections between very similar fossils is just as illogi-
cal as not seeing the connections between the two masses of water. For them, if they can't
see every bit of water flowing in full view, then there is no “transitional water” that links the
water on one side to the water on the other side of the bridge.
Finally, the importance of recognizing the difference between chains/ladders and
bushes/trees extends to another concept: mosaic evolution. Under the great chain of being
metaphor, every creature up the chain or ladder is more advanced than those below it and
more primitive than those above it. But evolution is a bush, not a ladder! Organisms evolve,
but they do not always move up the ladder. As sponges and corals show, they may retain
primitive features even though they have survived for 500 million years. In the case of many
animals (especially many fossils), not every anatomical feature of the animal evolves at the
same time. Some parts may be quite advanced, while others retain their primitive states. This
is the idea of mosaic evolution. Like a mosaic, the whole organism is composed of many tiny
parts, and not every part is identical or changes in the same way.
Human evolution, for example, is a classic mosaic. Some features, like our bipedal loco-
motion, appeared very early, while others, like our large brain size or tool use, appeared
much later. Early anthropologists expected to find fossils of humans where every feature was
evolving slowly and steadily toward the modern human condition, but that is not the case.
Each feature can evolve at a different rate.
Likewise, the classic transitional fossil Archaeopteryx is a mosaic of both advanced bird-
like features (asymmetric flight feathers, wishbone) and retained primitive dinosaurian fea-
tures (long bony tail, long fingers with claws, long robust legs without grasping big toe, and
many others). Creationists will exploit this misunderstanding of mosaic evolution to claim