For centuries, doctors were taught that human livers had three lobes, and even did dissections so they could see the liver and count its lobes, which they would always report to be three. The problem is that human livers have only two main lobes, or four lesser lobes if you’re following modern nomeclature, but the canonical text on anatomy and all things doctorish, the Roman-era Galen’s On the Usefulness of the Parts of the Body, said three, so three is was. Based on some other examples, it is now believed that his anatomy was partialy based on dissections of swine, who do have a 3-lobed liver, but the point remains: for centuries many of the most educated and intelligent people around believed not their own eyes and brains, but what they had been taught.
Before it was possible to do in-vitro tissue growth, use microscopes capable of recording the details of the very small, or program computers to to the heavy lifting of statistical analysis, all doctors could really do is just observe: brain damage doesn’t heal over time like cuts and broken bones do; women don’t get pregnant after a certain amount of time; this pigs liver only has three lobes and is delicious with these onions and garum. To conclude that brain cells don’t reproduce, ova are limited to a set number from birth, and that livers had three lobes are just logic taken to a wrong conclusion, then felt-tipped onto parchment for everyone to believe.
Neurons used to be thought of as wires. Now we’re discovering not only multiple channels of communication, but components that could be acting as processors, as well as hints of nanoscale structures and quantum effects that could be coming into play.
