My wife loves to garden. She gets the most pleasure from designing the landscape around our house. Since we have lived in our home, she has reworked the gardens in our yard several times. These redesigns, of course, involve putting in new plants and taking out old ones.
To my dismay, Amy doesn’t limit her activities to small plants and bushes. Her redesigns frequently involve trees. I can’t tell you how many trees I have taken out and planted in the last ten years. I dislike nothing more than cutting down a tree and taking out the stump. (In fact, as I write this piece there is a tree trunk in our backyard awaiting my attention.)
A recent “big picture” analysis of life’s history forces evolutionary biologists to rethink the landscape of life’s history. Instead of life unfurling in a gradual, branching tree-like fashion, the data indicates that the major transitions in the history of life happened explosively. This latest analysis chops down the evolutionary tree of life, one of the most enduring metaphors for evolutionary biology; and at the same time comports nicely with the RTB creation model for life’s history.
According to Eugene Koonin, the author of the article, phlyogenetic studies indicate that biological innovations happen abruptly in life’s history without any trace of intermediate forms. Examples include: 1) the origin of protein folds; 2) the origin of cells; 3) origin of bacteria and archaea and major divisions within these domains; 4) origin of eukaryotes and major eukaryotic divisions; and 5) the origin of animal phyla. These major transitions appear to occur rapidly. Once completed, diversification takes place in a slow tree-like manner.
Koonin proposes a mechanism to account for this pattern of changes. He suggests that at certain periods in life’s history extensive genetic “scrambling” (horizontal gene transfer, recombination, fusion, fission, transposition) took place. Most of this genetic chaos proved nonproductive, but on rare occasions—by chance—a stable genetic combination emerged. These robust islands of genetic novelty represent a transition to a new regime of biological complexity.
Koonin points out that his idea merely extends the speculations made by other biologists such as the late Stephen Jay Gould, Niles Eldredge, Lynn Margulis, Carl Woese, and Thomas Cavalier Smith, who have all suggested the identical pattern for aspects of the history of the biosphere.
The primary implication of Koonin’s proposal is that no evolutionary tree of life exists.
Koonin’s proposal is intriguing, and on the surface makes sense, but upon more careful reflection raises a number of questions. Why is this pattern of explosive innovation repeated throughout life’s history? What causes the genetic scrambling to take place? Why doesn’t this process happen continuously throughout the history of life? Why should the mechanism Koonin envisions ever result in coherent changes that lead to stable genetic islands that represent discontinuous increases in biological complexity?
Interestingly, the pattern Koonin identifies is similar to the one predicted by RTB’s creation model. This model asserts that a Creator intervened repeatedly to bring about progressive changes in life’s history. This intervention should produce discontinuities in the history of life and take place without any trace of transitional forms. If nothing else, Koonin’s analysis affirms that the patterns of the history of the biosphere match the predictions of the RTB model and validate the notion that a Creator must be responsible for life’s history.
Koonin’s hypothesis has one other interesting consequence for RTB’s creation model. Could he have identified a possible means by which God could have brought about biological innovations? Could the Creator have engaged in extensive genetic engineering to create? Perhaps He reworked preexisting genetic templates to generate new levels of biological complexity, a type of Divine genetic engineering. From an evolutionary perspective, it would look as if dramatic and rapid bouts of horizontal gene transfer, recombination, fusion, fission, and transposition took place. From a creation model vantage point, these changes are not random, but carefully orchestrated by the Creator.
This suggestion is fun speculation. What is certain, however, is that the landscape of life’s history has been reworked and the new design no longer features the evolutionary tree of life. Now that’s a tree stump I don’t mind removing.