50 Years Ago

La Gomera is one of the Canary Islands, lying in the Atlantic off the west coast of North Africa... Apart from a single road, which links San Sebastian, the capital, with the other three towns, the only means of travel between most points on the island is by rough paths which are little better than goat tracks; communication on the island is a great problem. But the Gomeros do communicate freely, across their ravines and from the valleys to the mountaintops... Long ago the Gomeros contrived an elegant solution to their problem; namely, a whistled language by which they speak to each other across miles of disjoined terrain. The silbo, as this language is called, is not a mere code or signal system, but a version of Spanish. It has extraordinary carrying power: it can be heard and understood clearly over far greater distances than shouted talk. On a windless day any practised silbador can be heard more than a mile away. A good performer can whistle messages three miles or more.

From Nature 6 July 1957.

100 Years Ago

Resort to experiment must be had in order to trace more accurately the circumstances associated with the spontaneous occurrence of cancer both in individuals and in families. The removal by surgical means of cancerous tumours occurring spontaneously in mice prolongs their lives and has enabled us to breed from them; we have, therefore, now the means of observing descendants of mice of known cancerous parentage, and by successively crossing other spontaneously affected animals with the offspring of cancerous parents, we can concentrate the hereditary tendency, if it exists. This concentration in large numbers of animals of a known age and in a known amount should enable us, in the course of a few years, to determine whether there is a family or only an individual tendency to the disease.

From Nature 4 July 1907.