The concept of the professional biologist - one who receives schooling and training in order to better study plants and animals - is a relatively new one. Much of our early knowledge about the natural world comes from our hunter-gatherer past; our more recent knowledge, up until the turn of the last century, comes from gifted amateurs. Charles Darwin went to school to become a doctor or a clergyman (but achieved neither career), not a field biologist; Alfred Russell Wallace barely went to school at all.
Many of the earliest naturalists made their investigations as a part-time hobby, and were doctors or churchmen. Not only were these two of the few professions of their era that resulted in substantial schooling, as well as the leisure time to pursue a hobby such as natural history, but they had the added benefit of potentially sending their practitioners off into the world, were discoveries could be made.
One such explorer was Pere ("Father") Armand David, a Lazarist missionary from the south of France. David had a passion for studying natural history - not only animals, but plants, rocks, and fossils as well. It was perhaps this interest in the natural world which saw him sent off to China in 1862. China was, at the time, a largely unknown country to many Europeans, and many of the specimens that David sent back to Paris were brand new to western science. Among the new species that he discovered were the golden monkey, the Chinese giant salamander, and a black-and-white bear that would later go on to become one of the most famous animals on the planet - the giant panda.
In my mind, however, the most important discovery Pere David made is the one he made in 1865, when he peeked over a wall a few miles south of Peking. The wall surrounded an imperial game park, one in which westerners were most definitely not allowed inside. Beyond the wall, David spied a herd of deer; even at the distance he viewed them from, the could tell that they were a brand new species, different from any deer he had ever seen in his life. There was a reason why: for the past three centuries, the deer had been found in that walled preserve and in that preserve alone. They were likely the first species to ever go extinct in the wild but survive in captivity. The Chinese called the deer milu, meaning "the four unlikes", saying that the deer looked like it had the parts of four different animals stuck together: cow, deer, horse, and camel.
Pleading with and bribing guards, David managed to secure skeletons and skins to send to Europe, where they were confirmed as a new species. Shortly afterwards, European governments approached the Chinese directly to request live specimens, a request which was granted. A small number of deer left China for zoos in London and Berlin. They were the lucky ones - within a few decades, a combination of natural disasters and civil unrest (cumulating in the Boxer Rebellion) drove the species to extinction in its native China.
The story of the animal that became known as Pere David's deer could have ended there, and it likely would have if not for one man: the 11th Duke of Bedford. The Duke collected most of the remaining deer and turned them loose on his Woburn Abbey where, protected from hunters, they bred. As the herd increased in size, it was split up and animals were sent to other zoos and breeders, until over one thousand were to be found in collections around the world. In some places, it has become so common that it is farmed for venison.
In 1985, the story of Pere David's deer came full circle, when two small herds were reintroduced to China, where they had been absent for decades. One herd was released in Jiangsu Province. The other was released in the former Imperial Deer Park where, 120 years ago, a curious French priest had peeked over a wall he wasn't supposed to peek over, and thereby saved a species from extinction.