Chromosome

Humans have 46 chromosomes. Yet after Theophilus Painter reported 48 in 1923, Genetics textbooks taught 48 for over 30 years. Some counted 46 themselves but doubted their eyes. In 1955 Joe Hin Tjio recounted to 46 — and old textbook photos had shown 46 all along.

In the 1920s, Soviet biologist Ilya Ivanov tried to create a "Humanzee," a human-chimpanzee hybrid. All experiments in Africa and the Soviet Union failed. Modern genetics confirmed this is impossible: humans have 23 chromosome pairs, chimpanzees 24.