Picture a scribe copying an important text. He has to be extremely precise so as not to distort the meaning. But sometimes he needs to make deliberate changes to improve the text. Living systems work in a similar way: they copy hereditary information with high fidelity, yet they can introduce changes that help them survive. For a long time, it seemed that precision and variability got in each other's way. A new study shows that they can complement each other.
The secret is that errors come in two kinds. Some are random, like typos when you're tired: they are usually harmful. Others appear on command, like a deliberate edit: they are directed and can be beneficial. In the authors' model, these two kinds are separated. A passive error blurs information in all directions, while active destabilization acts selectively, exploring only the relevant states. Selection, like a strict editor, weeds out random typos but preserves the right to meaningful changes.
This logic explains aging. With age, selection on late-life effects weakens, and the organism begins to invest less in maintenance but retains active variability. What looks like wear and tear may be partly a planned restructuring. A similar story applies to sexual conflict: the same genetic mechanism can be optimal in different ways for females and males, and then a burden arises, as if two architects were arguing about which door to leave in a building.
Experiments in yeast confirm the model. When the environment changes rapidly, it pays to switch quickly between states; when the environment is stable, precision matters more. Living systems do not merely react to current conditions; they also remember the path by which they arrived at their present state. Like an architect reinforcing the foundation, such a system does not abandon the door for remodeling: it just makes sure the door opens in the right direction.
In the replicator model, losing subunit B destroys the working complex, yet that very loss opens the path to a more efficient AAB complex: destroying part of a whole can be the condition for improvement.
The idea that controlled forgetting and regulated variability can be useful for adaptation echoes the concept of "forgetting" as a resource in Stanisław Lem's novel His Master's Voice.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.