About this episode
Something long considered reliable evidence for Darwinian evolution, the chemical similarity of living things, is now in question. In 1973, l eading Neo-Darwinist Theodosius Dobzhansky wrote that "nothing in biology makes sense except in light of evolution." He specifically pointed to "biochemical universals," or shared features in the chemistry of life , as evidence that all creatures "arose from inanimate matter only once" and that everything alive today descended from an universal common ancestor. Today, however, discoveries in molecular biology have complicated that conclusion. In fact, a new paper poses one of the strongest challenges yet to the idea that all life shares common chemistry . Though the title, "Scaling Laws in Enzyme Function Reveal a New Kind of Biochemical Universality," may be one that could excite only a scientist, what the authors describe should make everyone sit up and take notice. In fact, philosopher of biology Paul Nelson, in a piece at Evolution News , called the paper "the most interesting biology paper of 2022 so far." Its findings are precisely the opposite of what we'd expect if life evolved from a common ancestor. The authors, including theoretician Sara Walker and Dylan Gagler from Arizona State University, looked at enzyme functions across all the major groupings of life. They tallied the different functions, then plotted these against the total number of classified enzymes. They found that "as the enzyme space grows … so do the number of functions." In other words, there are very few "specific molecules and reactions" common to all living things. If your head just exploded, Nelson offers a helpful analogy borrowed from one of the paper's coauthors, Chris Kempes. The English language contains many words, or synonyms, that can mean approximately the same thing. If the sky is darkened, we could just say it was "darkened." Or, we could say that it became "murky," "shaded," "shadowed," dimmed," or "obscured." All these words mean, more or less, the same thing but with very different spellings and histories. According to Nelson, "a strikingly similar pattern" occurs among the chemicals that make life possible. The authors of the paper agree, writing that "[biochemical] universality cannot simply be explained due to phylogenetic relatedness." Or, stated more simply, living things don't look like they evolved from a common ancestor using the same basic components on a molecular level. Instead, many different enzymes are used to accomplish similar purposes. This is precisely the opposite of what Darwinism predicts. An editor of this paper, Eugene Koonin of the National Center for Biotechnology Information, has long argued that life lacks the "universal genetic core" that Darwinian evolution predicts. Instead, he says, living things show a pervasive pattern of what scientists have termed "non-orthologous gene displacement." That's a technical way of saying that the functions necessary to sustain life are carried out by different molecules coded by different genes in different species. Or, as original paper's coauthor Chris Kempes puts it , "there are a lot of 'synonyms'" at work in biology. This is just the latest instance of scientific evidence complicating the Darwinian picture, which has long been portrayed as tidy, straightforward, and conclusive. In fact, this is an instance where evolutionary assumptions hinder rather than help us understand how life works and where it came from. Nelson simply points out the obvious conclusion: Functional requirements fulfilled by a different molecular tool doesn't appear to be the product of a universal common ancestry. Instead, it looks more like what we see in computers, cars, language, etc. Function and purpose seem to take priority over hardware in the world of biochemistry. And if there is a mind behind life, we can conclude from these findings that He took great care to equip every living thing with exactly what it needed to thrive, instead of giving them all identical tools. Theodore Dobzhansky may have truly believed that nothing in biology makes sense without evolution, but it's not clear how he would have dealt with these findings. The more and more we learn in biology, the less and less it makes sense when thinking from evolutionary assumptions. The more we follow the evidence, the more it leads elsewhere.