The immune system defends hosts against internal and external biologic threats. It also records an antigenic map of the environment such that it can appropriately respond to stimuli as benign or threatening.
A lesser-known function of the immune system may be to sample the microbiome for potentially beneficial traits it can add to the host inventory. Rather than executing wholesale destruction of pathogens, the host can benefit by domesticating invading organisms or parts thereof. The function can be summed in the word “xenovation”, innovation achieved through the selection and integration of foreign traits. Implications for biologic evolution, meme evolution, and computing evolution are discussed.
Components of pathogens can be processed and rendered benign or useful through various mechanisms. A historical example of this phenomenon is the domestication of one prokaryote (or at least its energetic machinery) by another to form a eukaryote. A current example is the processing of pathogen antigens for surface redisplay to other players in the immune system. The ability to protect against reinfection is a trait acquired via the pathogen. It is intuitively appealing to speculate that the immune system is in a perpetual state of exploration for innovative traits through domestication.
The exact mechanisms by which immune cells domesticate microbial traits remain to be elucidated. How sequences associated with those traits might end up in the germline also remains to be investigated.
What is evident, however, is that host genomes demonstrate components that originated from the microbial world and were acquired somatically at some point rather than through direct lineage. In some cases, such sequences may produce nefarious traits or even help the pathogen. Examples include oncogenes. The extraction of sequences and traits may be an important part of the co-evolution of pathogens and the immune systems.
Memes are superior to genes in enabling evolution in part because they can be acquired somatically from others at low biologic cost. A host can learn memes by sampling a vast inventory of traits of others, processing them, and integrating useful ones into its own inventory. Meme transfers are most likely to occur when traits are encoded in communication universalities such as common language among groups.
The design of computing systems in many ways mimics that of their biological counterparts. When thinking about computing evolution, it could be useful to borrow once again from Mother Nature. Current computing designs involve operating systems and software programs that can evolve through updates. Digital viruses have become a substantial threat to the integrity of computing systems, and developing anti-viral software has become a major industry. Antiviral software currently consists of tools for identifying, quarantining and destroying potentially harmful invading code. What if host operating systems could sample viruses for useful traits to domesticate and integrate into the host computing system? What if, rather than executing wholesale destruction of rogue code, the antiviral software programs processed viruses and rendered their components benign or even useful? What if the antiviral software could be used to accelerate computing evolution?