50 YEARS AGO

Recent investigations have shown that some of the free amino-acids in amphibian embryos change in concentration during early development. These changes are of interest because they may be related to the synthesis of new, specific proteins...it is possible to carry out analyses of the free amino acids not only in whole embryos but also in different regions representing different tissue primordia. Any regional differences in free amino-acid content which might be related to the early synthesis of tissue-specific proteins can in this way be detected. The results already quoted indicate that at least dorsoventral regional differences do exist.

From Nature 6 August 1955.

100 YEARS AGO

It is sometimes said that natural selection has ceased as regards civilised man; but very clearly this is an error. All civilised and most savage races are very stringently selected by various forms of zymotic disease. Thus in England practically everyone is brought into contact with the organisms which give rise to tuberculosis, measles and whooping-cough. Abroad, malaria, dysentery, and many other complaints play a similar rôle...The result of all this elimination by diseases demonstrates natural selection very beautifully. Every race is resistant to every disease strictly in proportion to its past experience of it...These facts appear to establish conclusively two truths, first that evolution is due solely to natural selection, and second that variations, except, perhaps, in rare instance, are not due to the direct action of the environment on the germ-plasm, but are “spontaneous.” The Lamarckian doctrine is quite out of court. If ever acquirements are transmitted, it should be in the case of the profound and lasting changes affecting the whole body which result from disease; but in no instance is the effect produced by any disease on the race similar to that produced by it on the individual.

From Nature 3 August 1905.