This drawing is the oldest known sketch of an insect brain

After nearly 350 years, a depiction of a bee’s brain is getting some buzz.

A manuscript created in the mid-1670s contains the oldest known depiction of an insect’s brain, historian of science Andrea Strazzoni of the University of Turin in Italy reports January 29 in Royal Society Notes and Records. Handwritten by Dutch biologist and microscopist Johannes Swammerdam, the manuscript contains a detailed description and drawing of a honeybee drone’s brain.

The illustration, based on his own dissections, was just one of Swammerdam’s firsts. In 1658, he was also the first to see and describe red blood cells.

Since no one had previously reported dissecting a bee brain, Swammerdam based his descriptions on what was known about the brain anatomy of humans and other mammals. “He knew what to expect from or to imagine in his observations: in particular, the pineal gland and the cerebellum,” Strazzoni writes. Bees have neither of those parts but have brain structures that the 17th century scientist mistook for them.

But Swammerdam deserves some slack, Strazzoni suggests. He was working with single-lens microscopes and developing new techniques for dissecting and observing insects’ internal organs. Even with those crude instruments, he was able to identify some nerves and describe how parts of the brain connected.