Reacción a "A Spanish study published in Nature reimagines the origin of our cells as a story of microbial alliances"

This is a high-quality study that tackles a hot topic: identifying the sources from which the cell that eventually gave rise to all modern eukaryotes—including animals, fungi and plants—derived its genetic material.

The study’s greatest contribution is the identification of several bacterial sources, beyond the two expected ones—the Asgard archaea and mitochondria. Here, three other major ‘donors’ of genes are proposed, with a contribution similar to that of mitochondria in numerical terms.

Personally, the part I like best is the previously underestimated contribution of giant viruses, which are exceptional in that they have far more genes than other viruses, and with functions more akin to those of cellular life. This implies that the process of eukaryote formation was not a monogamous relationship between two organisms, but rather something more like a ménage à trois involving different organisms at different times (including viral diseases!), creating a picture of the hybrid origin of our ancestral genome. It is interesting because the message of this article conflicts with another paper also in Nature this year which argues the opposite. Obviously, methodological differences will underlie the differing conclusions, as determining what happened over a billion years ago is no easy task, but I personally believe this study is robust.