Evolving Thoughts

Not Darwin. Not Lamarck. Not the Greeks. A French physicist and mathematician...

Pierre-Louis Moreau de Maupertuis (1678-1759) was an interesting man. He devised what we now know as the principle of least action, and showed that the earth was flattened. Some other things he did, however, changed biology forever.

In 1735, the first edition of Linnaeus' Systema Naturae was published. Linneaus put out at least 13 editions of this in his lifetime, and the famous 10th edition was adopted in the 19th century as the "gold standard" - if Linnaeus named a species, that was its name thereafter, and if not, then the first person to name it after the 10th edition, published in 1758, got the credit.

In the course of the work, and other books such as the Fundamenta Botanica, Linnaeus defined species as

There are as many species as the Infinite Being produced diverse forms in the beginning. [Species tot sunt diversae quot diversas formas ab initio creavit infinitum Ens, Fundamenta botanica No. 157, 1736]

He repeated similar statements in his work elsewhere. This, of course, is a definition of what we might call stasis rather than of "species". Linnaeus, following John Ray, held that species never changed from how they were created.

Typically, we think this was overturned by Darwin, or, if we have read Darwin's own "Historical Sketch", added to the third edition of the Origin, we might think that evolution was invented by Lamarck. But in fact the first view of evolution in a scientific context was devised by Maupertuis, in the context of the Generation Debates that preceded the rise of genetics. Maupertuis noted that polydactyly, in the form of an extra finger on each hand, was passed on from generation to generation in a particular family in a 3:1 ratio, and each parent equally contributed. This, mark you, was 120 years before Mendel. In a text published finally as Venus physique (the physical Venus) in 1743, he speculated

Could we not explain in this manner [of fortuitous changes] how the multiplication of the most dissimilar species could have sprung from just two individuals? They would owe their origin to some fortuitous productions in which the elementary parts [of heredity] deviated from the order maintained in the parents. Each degree of error would have created a new species, and as a result of repeated deviations the infinite diversity of animals that we see today would have come about. [Systèm de la Nature 2:164, quoted in Terrell 2002:338]

We should not make too much of this - Maupertuis was not really aware of the need for a population of individuals with genetic variance, but it is clear that he allowed there to be two processes - variation in heritable traits that arose by lucky chance, which we would call an advantageous mutation, and diversification of species from common ancestors. Unlike Lamarck, who thought each species arose individually from nonliving matter, and subsequently changed in ways that were more or less predetermined, Maupertuis has species arising by the inheritance of mutations, and diversifying, in a manner very similar to Darwin. He lacks a theory of selection, but in some ways Maupertuis should be called the Last Common Ancestor of all evolutionists.

One point that is important to note here is that almost as soon as species fixity became the widespread opinion (with Linnaeus - although Ray had put it out there earlier, it wasn't until Linnaeus became popular, mostly among botanists at first, that species fixity became the standard view, contrary to many popular histories of biology), evolutionism was offered as an alternative. There's a good reason for this. Prior to Ray, nobody thought much about whether species were fixed or not. Aristotle held they could be formed by crossbreeding, and that there were deviations from the "proper" mode of a species. Right through the middle ages and early renaissance, there was a continuing view that species were wobbly sorts of things, and in the 18th century it became a fashion to gather species deviants - monsters and curiosities, as they were called - in cabinets to show to friends. It is simply false that species were always held to be fixed. But evolution, in the sense of a historical series of changes of species one into another, needed fixism as a contrast before it could be conceived, and it took all of 8 years after the Systema Naturae was first published...

Terrall, Mary. 2002. The man who flattened the earth: Maupertuis and the sciences in the enlightenment. Chicago: The University of Chicago Press.