December 19, 2012
One-hundred years ago, on December 18, 1912, British paleontologist Arthur Smith Woodward introduced the world to a tantalizing fossil: England’s most ancient human ancestor, perhaps one of the world’s oldest hominids. Best known as Piltdown Man, the “discovery” turned out to be the biggest hoax in the history of paleoanthropology. It’s a scientific crime that researchers are still trying to solve.
Piltdown Man consists of five skull fragments, a lower jaw with two teeth and an isolated canine. The first fossil fragment was allegedly unearthed by a man digging in gravel beds in Piltdown in East Sussex, England. The man gave the skull fragment to Charles Dawson, an amateur archaeologist and fossil collector. In 1911, Dawson did his own digging in the gravel and found additional skull fragments, as well as stone tools and the bones of extinct animals such as hippos and mastodons, which suggested the human-like skull bones were of a great antiquity. In 1912, Dawson wrote to Smith Woodward about his finds. The two of them—along with Pierre Teilhard de Chardin, a Jesuit priest and paleontologist—returned to the Piltdown gravels to continue excavating. They found additional skull fragments and the lower jaw. The following year Teilhard de Chardin discovered the lone canine tooth.
Smith Woodward reconstructed the Piltdown man skull based on the available fossil evidence. His work indicated the hominid had a human-like skull with a big brain but a very primitive ape-like jaw. Smith Woodward named the species Eoanthropus dawsoni (Dawson’s Dawn Man). It was the first hominid found in England, and other anatomists took Piltdown as evidence that the evolution of a big brain was probably one of the first traits that distinguished hominids from other apes.
At the time of the discoveries, the field of paleoanthropology was still in its infancy. The only other hominid fossils that had been found by 1912 were Neanderthals in continental Europe and the even older Homo erectus of Indonesia. As additional fossils were discovered elsewhere, such as Africa and China, it became harder to see how Piltdown fit with the rest of the fossil record. The growing collection of hominid bones suggested upright walking was the first major adaptation to evolve in hominids with increases in brain size coming millions of years later after the emergence of the genus Homo. Finally, in the 1950s, it became clear why Piltdown was so odd: It was a fake.
In 1949, physical anthropologist Kenneth Oakley conducted fluorine tests on the Piltdown Man bones to estimate how old they were. The test measures how much fluoride bones have absorbed from the soil in which they’re buried. By comparing the fluoride levels to those of other buried objects with known ages, scientists can establish a relative age of the bones. With this method, Oakley determined Piltodwn Man wasn’t so ancient; the fossils were less than 50,000 years old. In 1959, anatomist Wilfrid Le Gros Clark and anthropologist Joseph Weiner took a closer look at Piltdown Man’s anatomy and realized the jaw and skull fragments belonged to two different species. The skull was most likely human while the jaw resembled an orangutan. Microscopic scratches on the jaw’s teeth revealed someone had filed them down to make them appear more like human teeth. And all of the bones had been stained to make them look old.
Since the truth about Piltdown Man was revealed, there have been many suspects implicated in the forgery. Dawson was the prime suspect. But he died in 1916, so scientists never had the chance to question his possible role in the hoax. Teilhard de Chardin, who found the isolated canine tooth on his own, is another possibility. One of Smith Woodward’s colleagues, Martin Hinton, may have also played a role. In 1978, workers found an old trunk of Hinton’s at the Natural History Museum in London. The trunk held teeth and bones stained in a similar way as the Piltodwn Man fossils. Despite much interest and speculation, no one has ever definitively tied any of these men to the hoax.
And now, a century after the announcement of Piltdown Man, scientists are still intrigued by the fake hominid’s origins. A team of 15 British researchers are using new methods to investigate the mystery. Radiocarbon dating and DNA testing will help identify exactly how old the bones are and confirm the jaw belongs to an orangutan. Chemical tests will also help the team pinpoint where the bones came from and whether they were all stained in the same way.
It will be several months before the analyses are complete. But if it turns out all the material was stained in the same way, or came from the same location, then it’s more likely that just one person was responsible for the scientific fraud. And that person is likely to be Dawson. It turns out that Dawson was responsible for at least 38 fake finds during his amateur fossil-hunting career, the Telegraph reports. Chris Stringer, an anthropologist at the Natural History Museum in London and one of the scientists investigating Piltdown, speculates in a commentary in Nature that Dawson may have committed such hoaxes in an effort to achieve scientific glory.
Stringer writes that Piltdown Man serves as a good reminder for scientists to “keep their guard up.” I think it also highlights the importance of open science in the field of paleoanthropology. The hoax wasn’t uncovered until scientists unconnected to the discovery analyzed the evidence. Today, numerous hominid species are known based on just a handful of fossils that only a handful of scientists have ever had the chance to study. In no way do I think some of these fossils might be fake. But giving other scientists greater access to the complete hominid fossil record will not only allow more errors to be detected but will also stimulate new interpretations and explanations of how our ancestors evolved.
And with that sentiment, I end my last Hominid Hunting post as I head off to a new job with Science News. I’ve enjoyed sharing my love of all things hominid with my readers, and I’ve appreciated all of the spirited feedback.
Ed. Note: Thanks, Erin, for all of your blogging the past couple of years! It’s been a thrill and best of luck to you going forward. — BW
November 26, 2012
Humans and Neanderthals split from a common ancestor roughly half a million years ago. While many anthropologists will tell you we don’t really know who that common ancestor was, others will say we do: the species Homo heidelbergensis, or something very much like it. An even smaller portion will point to another possibility: a controversial species called Homo antecessor.
H. antecessor, which first came to light in the 1990s, is known almost entirely from one cave in northern Spain’s Atapuerca Mountains. While working at the Gran Dolina site from 1994 to 1996, a team of Spanish researchers found 80 fossils belonging to six hominid individuals that lived roughly 800,000 years ago. The hominids’ teeth were primitive like those of Homo erectus, but aspects of the hominid’s face—particularly the shape of the nasal region and the presence of a facial depression above the canine tooth called the canine fossa—were modern, resembling features of modern people. The unique mix of modern and primitive traits led the researchers to deem the fossils a new species, H. antecessor, in 1997.
In 2008, the researchers expanded the timeline of the species . At another cave site in Atapuerca, Sima del Elefante, scientists unearthed a partial lower jaw, as well as a few dozen stone tools, dating to about 1.2 million years ago. Outside of Spain, the only other potential evidence of H. antessor
fossils are stone tools found at a nearly 800,000-year-old English archaeological site named Happisburgh that might have been made by the species.
H. antessor‘s discoverers—including José Bermúdez de Castro of Spain’s National Museum of Natural Sciences, Juan Luis Arsuaga of the Universidad Complutense in Madrid and Eudald Carbonell of the University of Tarragona—say the species’ similarities with modern people, and its age, make it the best known candidate for the common ancestor of Neanderthals and Homo sapiens. They suggest H. antecessor may have evolved from a population of H. erectus living in Africa more than 1.5 million years ago and then migrated to Europe, journalist Ann Gibbons reported in Science when H. antecessor was first announced. Although the species has yet to be discovered in Africa, an African origin for H. antecessor may be necessary if it was indeed the direct ancestor of modern humans, which all fossil evidence suggests originated in Africa. Furthermore, the researchers say H. heidelbergensis is too similar to Neanderthals to be a direct ancestor of modern humans. Instead, H. antecessor gave rise to H. heidelbergensis, which then gave rise to Neanderthals.
But many anthropologists are not on board with this scenario. One problem is that most of the known H. antecessor specimens represent children, Gibbons reported. Only two of the six individuals found at Gran Dolina are thought to be adults, about 20 years old. Since most of the features tying H. antecessor to modern people were found in juveniles—whose bodies and physical features change as they grow up and go through puberty—it’s possible that H. antecessor adults didn’t really look much like H. sapiens at all. And if that’s the case, then it’s hard to argue the species had an ancestor-descendent relationship with us. The issue won’t be settled until researchers find good examples of complete adult H. antecessor fossils.
September 24, 2012
Neanderthals have a reputation for being dumb brutes. While modern humans (Homo sapiens) were painting cave murals, sculpting tiny figurines and crafting beaded jewelry some 30,000 to 50,000 years ago, Neanderthals weren’t making any art. At least, that’s the way it appears in the archaeological record. Now, a new study of bird fossils suggests our cousins were indeed capable of expressing themselves symbolically—using feathers as personal adornments.
In the last few years, researchers have reported a few archaeological sites with evidence that Neanderthals removed feathers and claws from birds such as raptors, presumably for ornamental purposes. Clive Finlayson of the Gibraltar Museum and his colleagues wanted to see how widespread this behavior was among Neanderthals. They published their findings last week in PLOS One.
To address the question, the team looked at Neanderthals’ association with fossils of raptors (including vultures and eagles) and corvids (including ravens and magpies). They focused on these birds because modern people generally don’t consume them and therefore Neanderthals probably didn’t either. Thus, finding these types of birds at an archaeological site helps exclude the possibility that our cousins were eating them. In searching almost 1,700 sites across Europe and Asia that contain bird fossils, the team noted that species with dark plumage were more common at Neanderthal sites than would be expected by chance alone. So, it seems Neanderthals across their geographic range liked black birds.
Next, the researchers looked at three cave sites on Gibraltar to examine more closely what Neanderthals might have been doing with these birds. The caves date from 57,000 to 28,000 years ago, before modern humans entered the region. The team found 604 avian skeletal pieces, representing at least 124 individual birds. With less than 3 percent of the bones containing the tooth marks of rodents or carnivores, Neanderthals are the likely reason the birds were brought into the caves.
More than half of the bones were wing bones. There’s no reason to expect wing bones to be disproportionately preserved in the fossil record, so this is another sign that Neanderthals were mainly interested in feathers, the researchers say. Furthermore, most of the bones with stone-tool markings are the wing bones. If Neanderthals were butchering the animals for meat, you’d expect to find the most markings on bones connected to fleshy areas, such as the breast bone.
Because soil bacteria rapidly decompose feathers, the researchers conclude our cousins weren’t using feathers as bedding. The only use that makes sense, Finlayson and colleagues argue, is plucking feathers to make headdresses, cloaks or some other adornment.
“Neanderthals, though different in a number of ways from modern humans, had comparable cognitive capacities that included symbolic expression,” the researchers write. Furthermore, they say, any differences in the art or artifacts left behind by the two species was the result of cultural differences, not intellect.
But does the capacity for symbolic expression mean Neanderthals had mental abilities that were on par with modern humans? It depends on who you ask. For decades, symbolism was considered the key cognitive trait that separated modern humans from other hominids. Today, anthropologists think there may be a range of abilities that define the human mind, such as planning for the future and processing disparate chunks of information at the same time (working memory). Until researchers can agree on the core features that characterize human cognition, it will be impossible to determine whether Neanderthal brains were really just like ours.
September 19, 2012
I was intrigued when I saw this headline over at NPR’s 13.7 blog earlier this week: “A Neanderthal-Themed Park for Gibraltar?“ As it turns out, no one’s planning a human evolution Disney World along Gibraltar’s cliffs. Instead, government officials are hoping one of the area’s caves will become a Unesco World Heritage site. Gibraltar certainly deserves that distinction. The southwestern tip of Europe’s Iberian Peninsula, Gibraltar was home to the last-surviving Neanderthals. And then tens of thousands of years later, it became the site of one of the first Neanderthal fossil discoveries.
That discovery occurred at Forbes’ Quarry in 1848. During mining operations, an officer in the British Royal Navy, Captain Edmund Flint, uncovered an adult female skull (called Gibraltar 1). At the time, Neanderthals were not yet known to science, and the skull was given to the Gibraltar Scientific Society. Although Neanderthals were recognized by the 1860s, it wasn’t until the the first decade of the 20th century that anatomists realized Gibraltar 1 was indeed a Neanderthal. Additional Neanderthal discoveries came in the 1910s and 1920s at the Devil’s Tower rock shelter, which appeared to be a Neanderthal occupation site. In 1926, archaeologist Dorothy Garrod unearthed the skull of a Neanderthal child near flaked stone tools from the Mousterian industry. In all, archaeologists have found eight Neanderthal sites at Gibraltar.
Today, excavations continue at Gorham’s Cave and Vanguard Cave, where scientists have learned about the life and times of the most recent populations of Neanderthals. In 2006, researchers radiocarbon dated charcoal to estimate that the youngest Neanderthal populations lived at Gibraltar as recently as 24,000 to 28,000 years before the present. Clive Finlayson, director of the Gibraltar Museum’s Heritage Division, has suggested that Neanderthals persisted so late at Gibraltar because the region stayed a warm Mediterranean refuge while glacial conditions set in across more northern Europe. Ancient pollen data and animal remains recovered from Gibraltar indicate Neanderthals had access to a variety of habitats—woodlands, savannah, salt marshes and scrub land—that provided a wealth of food options. In addition to hunting deer, rabbits and birds, these Neanderthals enjoyed eating monk seals, fish, mussels and even dolphins on a seasonal basis.
As with most things in paleoanthropology, the Neanderthal history at Gibraltar is not settled. Some anthropologists have questioned the validity of the very young radiocarbon dates. Why the Neanderthals eventually died out is also a matter of debate. Further climate change in Europe, competition with modern humans or some mix of both are all possible explanations.
September 5, 2012
The earliest known instance of cannibalism among hominids occurred roughly 800,000 years ago. The victims, mainly children, may have been eaten as part of a strategy to defend territories against neighbors, researchers report online in the Journal of Human Evolution. The new study shows how anthropologists use the behavior of modern humans and primates to make inferences about what hominids did in the past—and demonstrates the limitations of such comparisons.
The cannibalism in question was discovered in the Gran Dolina cave site of Spain’s Atapuerca Mountains. Eudald Carbonell of the University of Rovira and Virgili in Spain and colleagues found evidence of butchering on bones belonging to Homo antecessor, a controversial species that lived in Europe as early as 1.2 million years ago. Because no other hominid species has been found in the region at the same time as the butchered bones, the victims must have been eaten by their own kind, the team concluded in 2010 in the journal Current Anthropology (PDF).
Today, human cannibalism occurs in a variety of contexts: for nutritional value (often in times of starvation), as part of funerary rituals or during warfare. The different purposes of cannibalism can leave different patterns in the archaeological record. When humans consume other humans for purely dietary reasons, the victims are often treated just like any other prey. This is what the researchers found at Gran Dolina. Eleven individuals were butchered in a manner similar to that of deer and other mammals: Bones had cut marks in areas of muscle attachments and the skulls had signs of defleshing. Thus, H. antecessor appeared to eat its own kind for a nutritional purpose—but probably not because of a food shortage, as the team says there’s evidence of cannibalism over an extended period of time, dozens or even hundreds of years.
So why cannibalism? To find an answer, the researchers looked to chimpanzees. That’s because some aspects of H. antecessor cannibalism don’t resemble those of contemporary human cannibalism or cannibalism seen in Neanderthals or early modern humans living 100,000 years ago. For instance, nine of the 11 butchered individuals at Gran Dolina were children or adolescents compared with the largely adult victims of more recent human cannibalism.
Young victims is a pattern seen among chimpanzees. When female chimps range alone near the boundary of their territory, males from the neighboring group may kill and eat the females’ infants. Carbonell and his colleagues suggest the best explanation for this behavior is territorial defense and expansion. Males may attack to scare off other chimps as a way to protect their resources and gain new land to roam; such attacks are easiest against vulnerable females and their young, which make good meals. The team likewise concludes a similar explanation may have been the motivation behind H. antecessor cannibalism.
Whether this is a reasonable conclusion depends on some unanswered questions. For example, the researchers assume that the cannibalism was the result of intergroup violence and aggression, but they offer no evidence that the H. antecessor cannibals came from a different group than the victims. If they were all members of the same clan, then territorial defense doesn’t seem likely. It also seems unlikely if H. antecessor‘s social structure was vastly different from chimps—in which groups of probably related males band together to actively defend a territory while females in a community often forage alone with their infants.
It looks like the team has some more work to do.