Though it was based on very little evidence, many scientists thought that all mammalian brains, including the human brain, were made in the same way, with a number of neurons that was always proportional to the size of the brain.
Embora baseando-se em muito poucas provas, muitos cientistas pensavam que todos os cérebros de mamíferos, incluindo o cérebro humano, eram feitos da mesma forma, com um número de neurónios que era sempre proporcional ao tamanho do cérebro.