Lecture 2 – Narwhals, palindromes and Chesterfield station

From the 1992 lecture brochure:

Man seems superficially symmetrical but in reality he is profoundly asymmetric, particularly in respect of handedness. Everywhere we see this asymmetry also present in the natural world. While rats and monkeys do not show pawedness or handedness, shellfish are nearly always (when this applies) dextral, and most spiral-growing plants are sinistral. The horns of animals, the beaks of some birds and the claws of some crabs are asymmetric. While we can speculate about the origins of such chirality in nature, we realise that ultimately this is a chemical problem which we will start to come to grips with in the next lecture.

We can trace the influence of asymmetric man through the artefacts he has produced and the conventions to which he has become accustomed. Clocks go clockwise but don't have to; ropes twist in either direction. We write English from left to right, but writing from right to left unites Jew and Arab. Handedness in such matters as motor axles and gas fittings illustrates an important aspect of selectivity to which we shall return in Lecture 5, and emphasises the advantages of being asymmetric.

When we impose symmetry on music or prose (palindromes) the result is usually rather dull, but in contrast, palindromic sequences at the molecular level in DNA (Lecture 5) are of huge significance.

The conclusion emerges that chirality confers individuality, recognition, and specificity. All of these qualities will be seen to be vital in the struggle for existence.


BBC / Royal Institution




Charles Stirling



All lectures in the series