How Do Scientists Identify New Species? For Neanderthals, It Was All About Timing and Luck

Even the most remarkable fossil find means nothing if scientists aren’t ready to see it for what it is

Though the differences between Neanderthals and Homo sapiens may seem pronounced, scientists didn't always embrace the idea that humans evolved from other species. Allan Henderson/Flickr CC

Initially, scientists labeled the skull as human.

But there was something strange about it. The cavernous eye sockets sat beneath a bulging brow ridge; the domed roof seemed more oblong and less rounded than a human’s. Yet when Lieutenant Edmund Flint presented the skull to the Gibraltar Scientific Society the only note made by that group was where the so-called “human skull” was found—in Forbes’ Quarry. This was 1848, more than a decade before Charles Darwin’s On the Origin of Species would first suggest that new species could evolve from other species—even humans.

A victim of its era, the Gibraltar skull was discovered before scientists considered that other hominin species apart from our own had ever existed. But the fossil was actually the first adult Neanderthal skull ever found—and it spent the first 16 years of its afterlife hidden away in storage. Had researchers realized its significance a little earlier, we may not even call Neanderthals “Neanderthals”; they might’ve been Gibraltarians.

Today, it would be difficult to imagine overlooking the obvious differences between a Homo sapiens skull and that of a Neanderthal. We live in a world where scientists have identified numerous hominin species, from Homo erectus to Homo floresiensis (more affectionately known as “hobbits”). But in the mid-1800s, most scientists had no inkling that humans had evolved from other species. At this time, fossils were still mostly collected simply for the sake of curiosity and collection, not necessarily to publish scientific tracts, says Lydia Pyne, a science historian and the author of Seven Skeletons: The Evolution of the World’s Most Famous Human Fossils. “The scientific questions have to be primed. People inside and outside of scientific communities need to be ready to engage with these questions.”

In other words, in 1848, scientists lacked the context in which to evaluate such an unusual skull. Darwin was still hard at work on Origin of Species. Victorian scientists were still wrapping their heads around Charles Lyell’s 1833 work Principles of Geology, which promoted the idea that Earth’s history could be reflected in the fossil record and provided solid evidence for Earth being much older than 6,000 years, as traditionally asserted through Biblical studies. But even Lyell’s findings couldn’t help the Gibraltar Scientific Society with their unusual skull. Unfortunately, whoever discovered it didn’t record any details about the rock layer that it came from.

By contrast, a fragmented skull and leg bones discovered in Feldhofer cave offered a new opportunity for scientific documentation. Discovered in the Neander Valley, the fossils were meticulously surveyed and recorded by German schoolteacher Johann Fuhlrott, who made the discovery, and anatomist Hermann Schaaffhausen, who described it in a scientific paper in 1857. Though neither went so far as to name a new species, Schaaffhausen did note that the skull differed greatly from that of modern humans.

“The extraordinary form of the skull was due to a natural conformation hitherto not known to exist, even in the most barbarous races,” Schaaffhausen wrote in his paper. “The human bones and cranium from the Neanderthal exceed all [other fossils] in those peculiarities of conformation which lead to the conclusion of their belonging to a barbarous and savage race.”

Gibraltar skull
The Gibraltar skull is now housed in London's Natural History Museum. AquilaGib via Wikimedia Commons

Almost immediately, Schaaffhausen met with resistance from the scientific community. Famed pathologist Rudolf Virchow claimed the bones must belong to a Cossack soldier; the odd shape could be explained by the fact that the soldier’s legs curved from rickets and life on horseback. Most likely, Virchow claimed, the bones came from a soldier of the Russian army riding across Germany in 1814 during the Napoleonic Wars.

Meanwhile, back in England, the scientific community was undergoing an extraordinary upheaval. In 1859, Darwin released his bombshell. In 1861, paleontologist George Busk translated the Neander Valley paper from German to English (in German, “Neanderthal” means “Neander Valley”). In 1863, Thomas Huxley published Man’s Place in Nature, which went further than Darwin in arguing for the evolutionary connection between humans and apes. That same year, at the annual meeting of the British Association for the Advancement of Science, geologist William King proposed that the fossils from Germany belonged to a new species: Homo neanderthalensis.

That call for a new classification “opened up one of the longest standing debates in paleoanthropology—what is the precise taxonomic position of Neanderthals and, by extension, what was their contribution to the development of anatomically modern humans,” write John Murray, Heinz Peter Nasheuer and others in a 2015 article of the Irish Journal of Earth Sciences. “These were controversial and revolutionary ideas for their time.”

As the flood of arguments about the Neander specimen continued unabated, Busk made another important contribution: he had the Gibraltar skull moved from its island home at the southern tip of the Iberian Peninsula to London in 1864, where it could be further analyzed, and wrote about the fossil for the first time in a letter. He noted its similarity to the Neander bones, adding that skeptics would “hardly suppose that a rickety Cossack engaged in the campaign of 1814 had crept into a sealed fissure in the Rock of Gibraltar.”

Darwin and Huxley also examined the fossil, with Darwin calling it “the wonderful Gibraltar skull.” Both researchers concluded that it might belong to an extinct species of human, and Darwin certainly considered including it in his 1871 book The Descent of Man. But Darwin didn’t ultimately end up focusing on the Neanderthal debate. “It’s really not Darwin pushing this question of Neanderthals,” Pyne says. “He says this is interesting, but in some ways it’s just one thing of many.” What really pushed the conversation forward were continental European scientists who embarked on the quest to find more fossils.

The same summer that Darwin and the other members of the British intelligentsia were introduced to the Gibraltar skull, Falconer wrote to Busk about a possible designation for their new acquisition: “A hint or two about the names which I have been rubbing up for the Priscan Pithecoid [ape-like] skull, Homo var. calpicus, from Calpe, the ancient name for the Rock of Gibraltar. What say you?” He wasn’t the only one to propose an alternate binomial nomenclature. Other scientists offered Homo primigenius and Homo transprimigenius as well.

But once the new species designation was finally accepted, nothing stuck better than “Neanderthal.” At least, once the new species designation was finally accepted. “The presentation of the Gibraltar Neanderthal did little to settle the argument, at least in the short term,” writes paleoanthropologist Ian Tattersall in The Strange Case of the Rickety Cossack and Other Cautionary Tales from Human Evolution. He adds that even Busk didn’t seem fully convinced, writing at one point that the Gibraltar specimen was “still man, and not a halfway step between man and monkey.”

The Neanderthal question wouldn’t truly be settled until more fossils were found, especially that of the famed old man of La Chapelle-aux-Saints, a relatively intact Neanderthal skeleton discovered in 1908, including a skull that looked much like the one found in Gibraltar. As for the Gibraltar skull itself, now thought to belong to a woman from 50,000 years ago, it remains an example of what happens when new discoveries are made too soon, before the scientists are ready for the evidence.

“If we go back into all of the bins of every collection of every natural history museum, would we find something else that’s simply been miscatalogued or overlooked by history?” Pyne wonders. “I would speculate the answer is probably yes. There probably are things that historical circumstance has let us overlook.” Imagine the consequences if just one were as significant as overlooking the first Neanderthal.

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