Maupertuis, a member of the Royal Society from 1728, was a strong supporter of Newton's theories of gravitation. In 1738 he led an expedition to Lapland to measure a degree of longitude, confirming Newton's theory on the exact shape of the earth.
His Système de la nature (1751) challenged Needham's defense of spontaneous generation. In 1741, his Essai de cosmologie introduced the theory of the survival of the fittest, although few gave the idea much credence before Charles Darwin gave it a sounder foundation.
Maupertuis's Vénus physique (1745) challenged the preformation theory of genetics advocated by Jan Swammerdam, arguing that it could not account for the existence of hybrids or congenital "monsters." He argued instead that the embryo goes through a number of distinct developmental stages, rather than simply increasing in size over time.
In spite of his wide-ranging scientific interests and abilities, his temper made him a target of Voltaire's scorn in Micromégas.