But this is not a prediction of evolution. Believe me, evolution would not skip a beat if we found primitive life forms on a distant planet that had not changed for billions of years. Evolution makes no prediction that complexity should emerge.
Perhaps what Coyne and the evolutionists mean is that given that complex life exists today, then we should see it emerge from primitive forms. In other words, evolution predicts simple, not complex, beginnings.
But in that case, the prediction has not been a fruitful one. From the trilobite eye to the DNA code, early life does not show signs of simplicity. In fact, evolutionary reconstructions of what the ancient common ancestor to all life would have looked like come up with more complexity than simplicity. As evolutionist Nick Lane recently wrote:
There is no doubt that the common ancestor possessed DNA, RNA and proteins, a universal genetic code, ribosomes (the protein-building factories), ATP and a proton-powered enzyme for making ATP. The detailed mechanisms for reading off DNA and converting genes into proteins were also in place. In short, then, the last common ancestor of all life looks pretty much like a modern cell.
Similarly the cell's proteins, often referred to as the building blocks of life, do not reveal simple beginnings if evolution is true. As one evolutionist admitted last year:
It is commonly believed that complex organisms arose from simple ones. Yet analyses of genomes and of their transcribed genes in various organisms reveal that, as far as protein-coding genes are concerned, the repertoire of a sea anemone—a rather simple, evolutionarily basal animal—is almost as complex as that of a human.
You can read more about the failure of this evolutionary expectation here. Dogma doesn't help science.