That molecular evidence typically squares with morphological patterns is a view held by many biologists, but interestingly, by relatively few systematists. Most of the latter know that the two lines of evidence may often be incongruent. A recent case in point concerns the hypothesized evolution of whales. One group of toothed whales, the sperm whales, appear to be more closely related to the morphologically highly divergent baleen whales than to other odontocetes. Geneticists are discovering functions for what used to be apparent genetic debris.
Nucleotides belonging to chromatin are an example.
Despite all arguments made in the past in favor of considering heterochromatin as junk, many people active in the field no longer doubt that it plays functional roles. Just as, quite some time ago, populational thinking became a necessity in genetics, we need now to get used to populational thinking in regard to the function of nucleotides. They may individually be junk, and collectively, gold. The centromeric region contains at least one motor, which is involved in chromosome movement during cell division. The centromere also mediates a critical checkpoint that prevents completion of cell division until all chromosomes are properly attached to the mitotic spindle.