Proteins are a problem for theories of spontaneous origins. That is for many reasons.
They consist of dozens, or often hundreds, or even thousands of amino acids in a linear sequence. And while many different sequences will do the job, that number is tiny compared to the total number of sequences that are possible. It is a proverbial needle-in-the-haystack problem, far beyond the reach of blind searches.
To make matters worse, many proteins are overlapping, with portions of their genes occupying the same region of DNA. The same set of mutations would have to result in not one, but two proteins, making the search problem that much more tricky.
Furthermore, many proteins perform multiple functions. Random mutations somehow would have to find those very special proteins that can perform double duty in the cell.
And finally, many proteins perform crucial roles within a complex environment. Without these proteins the cell sustains a significant fitness degradation. One protein that fits this description is centrobin, and now a new study in the Journal of Cell Biology shows it to be even more important than previously understood.
Centrobin is a massive protein of almost a thousand amino acids. Its importance in the division of animal cells has been known for more than ten years. An important player in animal cell division is the centrosome organelle which organizes the many microtubules — long tubes that are part of the cell’s cytoskeleton. Centrobin is one of the many proteins that helps the centrosome do its job. Centrobin depletion causes “strong disorganization of the microtubule network,” and impaired cell division.
The new study shows just how important centrobin is in the development of the sperm tail. Without centrobin, tail, or flagellum, development is “severely compromised.” And once the sperm is formed, centrobin is important for its structural integrity. As the paper concludes:
Our results underpin the multifunctional nature of [centrobin] that plays different roles in different cell types in Drosophila, and they identify [centrobin] as an essential component for C-tubule assembly and flagellum development in Drosophila spermatogenesis.
Clearly centrobin is an important protein. Without it such fundamental functions as cell division and organism reproduction are severely impaired. Yet how did centrobin evolve?
Not only is centrobin a massive protein, but there are no obvious candidate intermediate structures. It is not as though we have that “long series of gradations in complexity” that Darwin called for:
Although the belief that an organ so perfect as the eye could have been formed by natural selection, is enough to stagger any one; yet in the case of any organ, if we know of a long series of gradations in complexity, each good for its possessor, then, under changing conditions of life, there is no logical impossibility in the acquirement of any conceivable degree of perfection through natural selection.
Unfortunately, in the case of centrobin, we do not know of such a series. In fact, centrobin would seem to be a perfectly good example of precisely how Darwin said his theory could be falsified:
If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down. But I can find out no such case.
Darwin could “find out no such case,” but he didn’t know about centrobin. Darwin required “a long series of gradations,” formed by “numerous, successive, slight modifications.”
With centrobin we are nowhere close to fulfilling these requirements. In other words, today’s science falsifies evolution. This, according to Darwin’s own words.