Perhaps science is a bit more like business than we think. In business, products get rebranded when vice presidents outnumber customers for the old brand. And now:
“Junk DNA” is a popular yet controversial concept that states that organisms carry in their genomes DNA that has no positive impact on their fitness. Nonetheless, biochemical functions have been identified for an increasing fraction of DNA elements traditionally seen as “Junk DNA”. These findings have been interpreted as fundamentally undermining the “Junk DNA” concept. Here, we reinforce previous arguments that this interpretation relies on an inadequate concept of biological function that does not consider the selected effect of a given genomic structure, which is central to the “Junk DNA” concept. Next, we suggest that another (though ignored) confounding factor is that the discussion about biological functions includes two different dimensions: a horizontal, ecological dimension that reflects how a given genomic element affects fitness in a specific time, and a vertical, temporal dimension that reflects how a given genomic element persisted along time. We suggest that “Junk DNA” should be used exclusively relative to the horizontal dimension, while for the vertical dimension, we propose a new term, “Spam DNA”, that reflects the fact that a given genomic element may persist in the genome even if not selected for on their origin. Importantly, these concepts are complementary. An element can be both “Spam DNA” and “Junk DNA”, and “Spam DNA” can also be recruited to perform evolved biological functions, as illustrated in processes of exaptation or constructive neutral evolution.
Nelson J.R. Fagundes, Rafael Bisso-Machado, Pedro I.C.C. Figueiredo, Maikel Varal, André L.S. Zani, What We Talk About When We Talk About “Junk DNA”, Genome Biology and Evolution, Volume 14, Issue 5, May 2022, evac055, https://doi.org/10.1093/gbe/evac055
So what happens when we find out that a lot of spam DNA does have a function?
You may also wish to read: Someone out there is actually defending junk DNA Can someone please tell them, the Titanic has sunk — its seaworthiness is no longer an issue?