Expert Insight: How new COVID-19 variants evolve and emerge

Nature is analogue. It is not a binary system. In the living world there are no explicit switches that discreetly turn systems on or off. Rather, nature adjusts systems through analogue dials, like an old radio - gradually changing variables to achieve balance and equilibrium to ensure that life is sustainable and carries on. Evolution proceeds in this way, with new life forms appearing and some disappearing over millennia - or, in the case of microbial pathogens (viruses, bacteria and parasites) over days or weeks. Evolutionary change results from two opposing forces : Positive selection reproduces beneficial genetic variations that enable the virus to survive, while negative selection pressure hinders the virus's survival and ability to reproduce. Evolution can be studied at the molecular level.