Jan Swammerdam was born in Amsterdam in 1637. He studied medicine at the University of Leiden, where he excelled in anatomical dissections. In 1679, he defended his thesis on respiration at the same university. However, to annoyance of his father, he would never start a medical practice but rather devoted his life to experimental scientific research.
Swammerdam made many anatomical and medical discoveries. He was an anatomical expert, who understood fixation and developed a novel method for preserving specimens by injecting hollow structures with hot wax. He further made pioneering dissections of the female genital tract, and described the anatomy of the uterus in detail.
Using the microscope, he also started to study a completely new field: the world of insects. Contrary to the then prevailing idea, Swammerdam showed that insects had internal organs and were just as complex as larger creatures. Furthermore, he was the first to show the process of metamorphosis as a gradual anatomical change of the same individual.
Jan Swammerdam combined anatomical work with physiological experiments. He was a pioneer in neurophysiology and developmental biology - terms that did not yet exist in his time. It was then believed that muscle contraction was mediated by spiritus animalis, a fluid or gas that flowed from the brain to the muscle. Swammerdam showed, using a frog nerve-muscle preparation, that muscle volume does not increase after excitation, which argues against the concept of spiritus animalis.
The scientific work of Jan Swammerdam was strongly influenced by his religious views. For him, studying the creatures of the earth revealed God's greatness. When giving a detailed description of lice, he saw the hand of God in this delicate anatomy. Swammerdam even left science for a year to dedicate his life to spirituality.
In 1680, at the age of 43, Jan Swammerdam died of malaria. Much of his research on entomology was brought together by Herman Boerhaave in the book Biblia Naturae (The Bible of Nature) after his death.