From Paul G. Ellis, Chichester, West Sussex, UK
Speaking to Richard Webb, Sean Carroll wonders whether bacteria have decision-making power or agency (15 February, p 34). Arguably, the earliest known “decision-making” in the burgeoning tree of life occurs with chemotaxis: single-celled life forms propelling themselves in response to a chemical stimulus, for example towards sources of nutrients.
Webb later quotes researcher Larissa Albantakis, who argues that the apparently deliberative quality of our agency sets it apart from this: it “is not just reflexes”. But bacterial chemotaxis is more than a single reflex action. It is a response to an environment that results in the selection, over alternatives, of one near-optimum direction to move in.
Information scientist Susanne Still says that agents follow rules that must fulfil certain criteria, including some element of memory storage and recall. Evolutionary processes constitute a memory function and provide this feedback, but over generations rather than within an individual cell.
So could focusing on a primitive form of agency – the ability to select one optimal direction from many – in a system as simple as a single cell help determine whether agency can, in principle, be explained in purely physico-chemical terms?
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