I was reading through a stack of Scientific Americans this morning (catching up on my reading) and I came across and interesting article by Luis P. Villarreal from last December’s issue. Are Viruses Alive? discussed current thinking about viruses and whether they can be considered alive. The author thinks they exist of the fringes of life, and certainly are more active in evolution than climate change or other external factors since viruses deal in genetic material. Deciphering the human genome, scientists discovered bits of viral DNA in our genome. Viral genetic material is part of the genomes of most complex species, so apparently viruses can insert themselves into cells for long periods of time, even permanently. Towards the end of the article I read this shocking paragraph:
In fact, along with other researchers, Philip Bell of Macquarie University in Sydney, Australia, and I contend that the cell nucleus itself is of viral origin. The advent of the nucleus – which differentiates eukaryotes (organisms whose cells contain a true nucleus), including humans, from prokaryotes, such as bacteria – cannot be satisfactorily explained solely by the gradual adaptation of prokaryotic cells until they became eukaryotic. Rather the nucleus may have evolved from a persisting large DNA virus that made a permanent home within prokaryotes. Some support for this idea comes from sequence data showing that the gene for a DNA polymerase (a DNA-copying enzyme) in the virus called T4, which infects bacteria, is closely related to other DNA polymerase genes in both eukaryotes and the viruses that infect them. Patrick Forterre of the University of Paris-Sud has also analyzed the enzymes responsible for DNA replication and has concluded that the genes for such enzymes in eukaryotes probably have a viral origin.
Think of that. Higher forms of life developed because some enterprising virus managed to insert itself into a bacterium and stay there permanently, eventually becoming an integral part of the eukaryotic cell. You, me, Fido your dog, the trout you ate for dinner, that oak tree out in the yard, all this from a virus hijacking a cell billions of years ago. Wow.