Finding Common Ground
I think it’s safe to say that most people don’t think of bacteria or archaea on a regular basis—if and when they do, the common perception is that they are simple organisms living very unremarkable lives. We all know the textbook narrative: They are ‘‘bags of enzymes.’’ They don’t have organelles. They have some cool tricks up their sleeves allowing them to thrive in extreme environments. Some cause disease, while others are beneficial to their macroscopic cohabitants. Whatever they are, they’re decidedly ‘‘different’’. Out of sight, out of mind. But here’s the thing: they’ve been around for a lot longer than we have, experimenting, optimizing, and streamlining themselves to be some of the best biological machines on the planet. They can’t be ‘‘primitive’’ when in fact they’re still adapting to our changing climates, evolving new capabilities to fill new niches, and overcoming every roadblock we try to throw at them. And somewhere along the way, about halfway along the 3.5 billion-year timeline between the origin of life and present day (Betts et al., 2018), at least a couple of those so-called simple, single-celled things embarked on an incredible journey. While it has been widely accepted for many years that our origins as eukaryotes lie in the building blocks of both bacteria and archaea, advances in genomics are illuminating just how close our microscopic cousins might be and how so many of our sophisticated innovations long thought to be eukaryotic signatures might have actually been invented long, long before our time. A new story is coming into focus—one of commonalities and shared beginnings. While evidence of the alphaproteobacterial origin of mitochondria and cyanobacterial origin of chloroplasts has given us high confidence in the validity of the endosymbiotic theory first proposed by Lynn Margulis in 1970, we are still learning about features we eukaryotes borrowed from our bacterial