In 1922, scientists announced the discovery of a “remarkable tooth” from a Nebraskan hillside. This tooth had the potential to change the story of the human past, scientists argued. The president of the American Natural History Museum, Henry Fairfield claimed that the fossilized tooth belonged to an ape–the first recognized ape in North America. But this was not just any ape, Osborn continued, it was an ape that was closely related to humans, a “missing link.” It was a savage creature, Osborn stated, but it was unmistakably the “ape man of the Western World.” He named the tooth a new genus and species: Hesperopithecus haroldcookii, meaning ape of the land where the sun sets.
Ape of the Land Where the Sun Sets
Hesperopithecus, known generally as Nebraska Man, was one of many “discoveries” of fossils human ancestors in the early 20th century. Interest in human evolution had risen significantly, and both scientists and amateurs alike were scouring the globe looking for hard evidence to link humans back to their evolutionary cousins, the great apes. Even the London Times noticed this fossil-hunting fervor, referring to anthropologists as the “newcomer to the aristocracy of science” whose search for ancestors flaunted a sense of zeal that “has been carried to its highest pitch.” As fossil evidence began to role in, however, the tone of that pitch began to waiver.
The idea of an ancient hominid tooth located in Nebraska was inconsistent with the contemporary theories surrounding where and when humans had evolved. Additionally, a single tooth was considered by some to be insufficient evidence, casting doubts on the validity of Hesperopithecus. Indeed, some scientists warned that this small bit of bone was a “frail and hazardous basis upon which to build such tremendous conclusions.”
Some scientists really wrestled with the legitimacy of the Nebraska Man, waivering back and forth between believing and doubting. British anatomist Grafton Elliot Smith, for example, welcomed Hesperopithecus into the human family overall. He was enthusiastic, though he did caution “it is important to remember that even paleontologists” (and anthropologists) “are not infallible.” Smith acknowledged that many scientists had “grave doubts” about the fossil, but ultimately conceded that Professor Osborn and others who studied the tooth “have had a wider experience of such material than many other paleontologists,” and are “men of exact knowledge and sound judgment.”
To doubters, Osborn retorted that fossil evidence is fragmentary by nature, arguing that the tooth was a tiny bit of “truth” that should not be “banished” simply because it didn’t fit with preconceived notions. Smith’s statement of infallibility soon rang true, however, as further excavations in Nebraska revealed that Hesperopithecus was not a primate at all–instead the tooth belonged to an extinct species of pig. The Nebraska Man was quickly retracted in a Nature paper titled “Hesperopithecus was neither ape nor man”, five years after his discovery.
The Fragmentary Fossil Record
The story of Hesperopithecus is one of a number of cautionary tales in the history of paleoanthropology. But are such mistakes of misidentification possible today? The fossil record of human evolution has certainly accumulated over the years, but it continues to be fragmentary. Faced with this partial the record of the past, scientists continue to be tempted to speculate from small bits of bone like isolated teeth or partial jaws.
This week, a headline made waves by arguing that the hominin lineage may have originated in Europe, not Africa as previously believed. The evidence for this claim, however, was a tooth and fragmentary jaw. Many scientists have since pointed out that this is too small a piece of evidence on which to hang a large claim. The legend of Hesperopithecus reminds the community to proceed with caution, especially when tying big claims to evidence as fragmentary as a single tooth.