“Ze Little Grey Cells”: Agatha Christie’s Poirot and Neuroanatomy

First published May 15, 2022

Among the fictional characters that have stood the test of time in short stories, novels, movies, stage, and television shows are Agatha Christie’s two extraordinarily insightful fictional detectives. The first, Hercule Poirot, the bachelor Belgian private investigator, who is diminutive, five-feet-four inches tall, with a singular, carefully groomed moustache, an egg-shaped head, and who dresses elegantly and fastidiously, appeared in 1920. He was featured in numerous Christie stories over 53 years and continues on in derivative movies, television and stage plays (e.g. Murder on the Orient Express). Like all detectives, Poirot uses clues, that is physical evidence, but he supplements those findings with insightful knowledge of human nature and an understanding of psychology to reach a dramatic conclusion to the “who dunnit”. A complex, insightful solution satisfies his immodest opinion that he is “the greatest detective in Europe”. Christie’s second detective, an “amateur”, Miss Jane Marple, first appeared in 1927 in a magazine story, as a spinster of intelligence and determination. She populated many of Christie’s novels and short stories for 46 years. Christie having a gifted female amateur detective, Miss Marple, as the heroine in the 1920’s could be construed as her effort to move from a male-centered world. To have Poirot refer to the need to apply his “little grey cells” to the solution of the crime, was an early invocation of neuroscience. When the brain and spinal cord are examined by the eye, they each have two contrasting colors, grey and white. The grey matter contains nerve cells from which messages originate, and the white matter contains the cell extensions or axons that carry their messages to the tissue for which they are intended. A classic example of the two tissues’ functional differences is in the decision to move a muscle. This message starts in the cells of the grey matter in the brain and travels down the cell axons in the white matter of the spinal cord. Then, nerves leave the spinal cord and innervate the muscle in question. This neural message causes the muscle to move in the manner dictated by one’s thought, which originates in the grey matter of the brain. Remarkable! Hence, Poirot’s focus on “the little grey cells”; Christie understood that the insights Poirot needed to solve a complex case originated there. Alice Jo and I are fans of Christie. We have read many of her stories in which the crime-solver is Miss Marple or Poirot. We have enjoyed the Public Television System (PBS) recreations of both detectives. David Suchet, featured on PBS, most closely meets Christie’s description of Poirot’s appearance and behavior. (Figure 1) We are watching the Poirot mysteries being reshown on PBS. We had seen them thirty years ago, yet they seem fresh, perhaps because of the aging of our little grey cells. Although a Belgian, Poirot lives and works in the United Kingdom (see Figure 1 legend). The other principal characters in the Poirot stories are Inspector (James) Japp an arrogant chief inspector at Scotland Yard who always gets it wrong and depends on Poirot to get it right, Miss (Felicity) Lemon, Poirot’s devoted and frequently helpful assistant and Captain (Arthur) Hastings, his side-kick and right-hand man, who is helpful to Poirot but is often in the dark about the detective’s thinking and direction making him a comic, albeit a sophisticated, foil. The Mousetrap, a murder mystery play by Agatha Christie, opened in London's West End in 1952 and is still running, with only a short COVID-19 interruption. Christie has been dubbed the “Queen of Crime”. To bring concern about “the little grey cells” into our contemporary life, neuroimaging indicates that SARS-CoV-2, the cause of COVID-19 can injure and shrink the grey matter of the brain. This effect may account for a prolonged loss of smell and a prolonged cognitive impairment associated with COVID-19.

Figure 1. David Suchet as Poirot on PBS. Christie, a British volunteer nurse during World War I, conceived of her detective circa 1915. In late summer 1914, the Germans surprisingly attacked Northern France through Belgium (the Schlieffen Plan) to avoid French fortifications near the French-German border. Many Belgians fled to various countries, including Great Britain. Christie fashioned her detective as a Belgian émigré in Britain and a fastidious dandy, but with highly functional “little grey cells”.