The first time someone depicted human evolution in a horizontal sequence was 1863, four years after Darwin published “On the Origin of Species,” the foundation to evolutionary biology. Darwin depicted evolution very differently, using a branching diagram that showed evolution as a complex process where no single organism is the sole descendant of any other — pretty close to how biologists view it today. But despite how wrong it was, the simple, logical progression of the “monkey-to-man” image was more engaging. It has lived on in various forms to this day, most famously in Rudolph Franz Zallinger’s 1965 illustration “The Road to Homo Sapiens.” So why is it wrong? Evolution is not regular and predictable like the image suggests. It’s messy, hitting dead ends at some points and turning back around at others. Perhaps evolutionary biologist Stephen Jay Gould said it best: “Life is a copiously branching bush, continually pruned by the grim reaper of extinction, not a ladder of predictable progress.”
From right to left, the image depicts Homo Sapiens, Cro-Magnon, Neandertal, Ramepithecus, Oreopithecus, and Dryopithecus.00:23
- Some of the species in the image are just wrong. The specimen that Cro-Magnon was based on turned out to be a modern Homo Sapiens, so it didn’t technically exist. We also didn’t evolve from Neandertals: we had a shared ancestor, but we coexisted until around 40,000 years ago.01:49
- Evolution isn’t a linear process. There are plenty of other organisms with which we share ancestors that are just as successful, like chimps and orangutans.