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Eugene Dubois discovered the first hominid fossils in Indonesia when he unearthed Homo erectus bones at Trinil in 1891 and 1892. Image: Wikicommons

Indonesia is the overlooked birthplace of professional paleoanthropology. In Europe in the mid-19th century, scientists discovered an extinct hominid species for the first time: Neanderthals. Actually, it’s more accurate to say Neanderthal fossils were found by lay people who then brought them to the attention of well-known anatomists. It wasn’t until 1890 that a researcher went into the field looking for hominid bones. Eugene Dubois, a Dutch medical doctor, traveled to Indonesia, then a Dutch colony, in search of human ancestors. In 1891, he discovered Homo erectus fossils and made hominid hunting a proper endeavor—and made Asia a destination for paleoanthropologists.

Trinil: Dubois’ discoveries occurred near the village of Trinil in central Java. His first find was a skullcap, now known to date to 700,000 to 1 million years ago. The skull looked humanlike, but it had thick bones, heavy browridges and a low, sloping forehead. A year later, in 1892, Dubois recovered a nearly complete thigh bone that looked almost modern. He decided the bones belonged to an extinct species that was a “missing link” between apes and humans. He named the species Pithecanthropus erectus (“erect ape man”). Sometimes called Java Man, the species today is called Homo erectus.

Ngandong: Dutch researchers discovered more H. erectus fossils, representing 15 individuals, in Java in the 1930s near the village of Ngandong on Java’s Solo River. Until recently, paleoanthropologists thought the Ngandong bones represented a very recent H. erectus population. Thought to be perhaps as young as 30,000 to 50,000 years ago, these hominids could have been contemporaries of Neanderthals and modern humans living in Europe and West Asia. But more recent fieldwork and dating analyses suggest the Ngandong hominids lived much earlier, sometime between 143,000 and 546,000 years ago.

Mojokerto: In 1936, an assistant working with the Dutch Geological Survey unearthed a partial skullcap of a two- to three-year-old child in eastern Java. Team member Ralph von Koenigswald, a German paleontologist, recognized the skull as belonging to an early hominid, H. erectus. Although the exact location, and therefore age, of the fossil has been questioned in recent years, scientists generally think the Mojokerto skull dates to about 1.8 million years ago. That makes it one of the oldest hominid bones ever found outside Africa.

Sangiran: Between 1937 and 1941, von Koenigswald found additional H. erectus fossils at the site of Sangiran in central Java. The finds included three partial skulls, partial jaws and dozens of isolated teeth. These fossils, dating to more than one million years ago, helped confirm the validity of the species status of H. erectus. Today, tourists can visit the fossil site, which is home to ongoing excavations as well as a museum.

Flores: Indonesia’s most recent hominid discovery was a big shocker. In 2004, a group of researchers from Indonesia and Australia announced they had found an unusual collection of fossils on the Indonesian island of Flores. The bones belonged to a small-brained hominid that stood less than four feet tall and weighed less than 70 pounds—yet some of the fossils were just 17,000 years old. The researchers decided the “Hobbit” belonged to a new species, Homo floresiensis. Once the species’ ancestor, perhaps H. erectus, arrived on the island, the hominid evolved to be smaller as an adaptation to living on a small island. Critics, however, say the Hobbit is actually a modern human with some kind of growth disorder.

In 1921, a miner found Kabwe 1, also called the Broken Hill Skull. Image: Gerbil/Wikicommons

Hominid hunting requires a lot of hard work and determination. Paleoanthropologists can spend months surveying a landscape, studying the fine details of a geologic formation and sifting through mounds of sediments. But sometimes all it takes is dumb luck. Here’s a look at five hominid fossil discoveries that were complete accidents.

Neanderthal 1 (1856): While quarrying limestone, workers unearthed some bones in Feldhofer Cave in Germany’s Neander Valley. The men thought they had found the remains of an old bear and tossed the fossils aside. The quarry’s owner gave one of the bones, a skullcap, to schoolteacher Johann Fuhlrott. Although the skull had thick browridges and a sloping forehead, Fuhlrott recognized the fossil was more human than bear and turned it over to Hermann Schaffhausen, an anatomist at the University of Bonn who concluded the skull belonged to an ancient human race. In 1864, Irish geologist William King pointed out that the cave sediments in which the fossil was found dated to more than 30,000 years ago. Due to the great antiquity, he suggested the skullcap belonged to an extinct species of human, one that he named Homo neanderthalensis. This was the first time anyone had recognized a fossil as being a part of an extinct hominid species. But Neanderthal 1, as the skullcap is now called, wasn’t the first Neanderthal ever found. A skull discovered in Belgium in 1829 and another one found in Gibraltar in 1848 were later classified as Neanderthals.

Cro-Magnon (1868): Clearing a path for a road in southern France, construction workers exposed the entrance to a limestone rock shelter. The cave was named Cro-Magnon and inside workers found the skeletons of four adult Homo sapiens and one infant, in addition to stone tools and perforated shell beads. Researchers realized these humans were quite old because their bones were found in association with the remains of mammoths and lions. (Radiocarbon dating in the 1950s confirmed that these people lived roughly 30,000 years ago.) The name Cro-Magnon eventually became synonymous with early Europeans from this time period.

Kabwe 1 (1921): At the Broken Hill (now Kabwe) iron and zinc mine in Zambia, Swiss miner Tom Zwiglaar came across several fossils, including a skull, jaw and leg bones. The specimens looked human, but the skull also had features that didn’t resemble any modern people, such as heart-shaped browridges and a sloping forehead. The bones were sent to British paleontologist Arthur Smith Woodward. He decided the fossils represented an extinct hominid species he called Homo rhodesiensis (Zambia was once part of the British colony Northern Rhodesia). Today, the Kabwe 1 skull, dating to 300,000 to 125,000 years ago, is classified in the species Homo heidelbergensis, which some paleoanthropologists think was the common ancestor of Neanderthals and modern humans.

Taung Child (1924): Clearly, mines are a great place to stumble across hominid fossils. The discovery of the Taung Child is no exception. In 1924, a mining official noticed a monkey skull lodged in a chunk of limestone that had been blasted from a quarry near Taung, South Africa. The official brought the skull home, and his son later showed to it Raymond Dart, an anatomy professor at the University of the Witwatersrand. Intrigued by the specimen, Dart had the quarry send over some more rubble that might contain fossils. Inside was a promising rock that looked like the surface of a brain. Careful scraping with a pair of knitting needles allowed Dart to liberate the brain’s corresponding face from another piece of rock. The face looked like an ape, but Dart recognized that aspects of its brain looked like a human’s. He believed the fossil represented an intermediate species between apes and humans, and named it Australopithecus africanus. It was the first discovery of an Australopithecus, and it spurred other hominid hunters to start looking for our ancestors in Africa.

Australopithecus sediba (2008): This discovery wasn’t completely unexpected, but the finder of the fossil was. Lee Berger of the University of the Witwatersrand was surveying South Africa’s Malapa Cave with his Witwatersrand colleague Job Kibii when Berger’s 9-year-old son Matthew announced he had found something: a rock with a hominid collar bone sticking out. Additional excavation led to the recovery of two hominid skeletons dating to nearly two million years ago. The older Berger decided the skeletons represented a new species, Australopithecus sediba, which is a leading candidate for ancestor of the genus Homo.

KNM-ER 1470, a Homo rudolfensis specimen, is one of the fossils you can examine at African Fossils. Image: José-Manuel Benito Álvarez/Wikicommons

Last fall, I offered my picks for the best places to see hominid bones online. I thought it was time to share some more great human evolution Web sites that I’ve discovered.

Fossilized.org: This site is filled with a ton of information on the different places where hominid fossils and stone tools have been found. The homepage is a world map locating the archaeological sites. Next to the map is a list of some of these places; clicking on a name brings up a satellite image of the area and more information on the location’s significance. The site also  includes a timeline of important events in the history of paleoanthropology, a geologic timescale and a list of all the hominid species, including the year the species was first recognized. Anthropologist William Henry Gilbert of California State University, East Bay made the Web site.

African Fossils: A virtual anthropology lab that feels like a video game, this site is the brainchild of Louise Leakey, Louis and Mary Leakey’s granddaughter. It displays specimens from the collections of the National Museums of Kenya. Still a work in progress, the site lets you navigate through the lab and click on different objects to learn more about them. The best part is playing with the digital, 3-D hominid fossils and rotating them to see the specimens from different angles.

Ardipithecus Handbook: Brought to you by the Discovery Channel, this Web site is an interactive guide to the approximately four-million- to six-million-year-old genus, with a special emphasis on the famous skeleton named Ardi. The handbook offers background on Ethiopia’s Middle Awash, where Ardi and other hominids have been found—including an interactive map that locates and describes different hominid fossils discoveries—as well as a discussion of the genus’s place in the human family tree. The site also has an interactive Ardi skeleton that provides 3-D views of different bones.

Bones, Stones and Genes: The Origin of Modern Humans lecture series: The subject of the Howard Hughes Medical Institute’s 2011 Holiday Lectures was human evolution, and the institute has archived high-quality videos of these talks. The lectures are given by top anthropologists and are a great introduction to the science of human evolution. Paleoanthropologist Tim White of the University of California, Berkeley discusses his Middle Awash field site, where his team found Ardi and the 160,000-year-old Herto fossils, some of the earliest remains of Homo sapiens. Genetecist Sarah Tishkoff of the University of Pennsylvania offers a tutorial in human genetics. And archaeologist John Shea of Stony Brook University describes the earliest stone tools and the ways in which scientists study them. His talk also includes tool-making demonstrations.

The 1972 Homo rudolfensis skull is combined in this composite image with one of the lower jaws found at Koobi Fora, Kenya. Image: © Photo by Fred Spoor

In March, I compiled a list of my top ten hominid fantasy finds. Item number six: more Homo habilis and Homo rudolfensis fossils. The two species are the oldest members of the genus Homo. H. habilis lived roughly 2.4 million to 1.4 million years ago while H. rudolfensis lived about 2 million years ago. But where some scientists see two contemporaneous species, others recognize just one. These researchers say the fossils of H. rudolfensis may simply represent physical variation within the H. habilis species due to differences based on geography or sex. It’s a hard question to answer as there’s only really one good H. rudolfensis fossil.

But as it turns out, fantasies really can come true: A team of researchers announced today in Nature that they’ve dug up three new fossils that match the lone H. rudolfensis specimen. The new finds confirm that at least two species of Homo lived in Africa 2 million years ago.

In the 1960s, Louis and Mary Leakey discovered the species H. habilis while working at Tanzania’s Olduvai Gorge. In 1972, Bernard Ngeneo, a member of a team led by the Leakeys’ son Richard, discovered a 2-million-year-old skull lacking a lower jaw at Kenya’s Koobi Fora site near Lake Turkana. The skull, known as KNM-ER 1470, sort of looked like H. habilis, but was different in several key ways, such as being much bigger with a flatter face. Some anthropologists suggested the skull belonged to a male H. habilis and that’s why it was bigger. Other researchers said the differences were too great to be explained by sex, and they gave the skull the name H. rudolfensis because Lake Turkana was once known was Lake Rudolf.

The three new fossils also come from Koobi Fora, dating to 1.78 million to 1.95 million years ago. They also have a connection to the Leakeys. Meave Leakey, a paleontologist at the Turkana Basin Institute, is married to Richard Leakey, and Louise Leakey, Meave and Richard’s daughter, led the team that made the discoveries.

The fossil KNM-ER 62000 is the face of a juvenile. Although much smaller than the KNM-ER 1470 skull, both fossils share the same shape and features. The researchers say this is evidence that H. rudolfensis was a separate species rather than being the male version of H. habilis. The other two fossil finds are of lower jaws, which seem to match the shape of the upper jaws of KNM-ER 1470 and KNM-ER 62000. This further suggests that H. rudolfensis is indeed a separate species because the new jaws are much different from known H. habilis jaws: They are shorter and more rectangular.

One of the lower jaws recently unearthed at Koobi Fora, Kenya. Image: © Photo by Mike Hettwer, www.hettwer.com, courtesy of National Geographic

The team doesn’t outright say that the new fossils plus KMN-ER 1470 should officially be called H. rudolfensis. They’re cautious because of a fossil lower jaw from Olduvai Gorge called OH 7. OH 7 is the type specimen of H. habilis—in other words, it’s the fossil that scientists use to define the species. But the fossil is very distorted. If scientists were to reanalyze the jaw and discover it actually belongs in the same species as the newly found jaws, then by the rules of taxonomy, researchers would have to call that species H. habilis. And then the species we now call H. habilis would need a new name. (Let’s hope that doesn’t happen because it would be very confusing.)

Regardless of what the fossils are called,  scientists now have much better evidence that two species of Homo lived in Africa at the beginning of the Pleistocene. That number grew to three species with the emergence of Homo erectus 1.89 million years ago. Now there are new questions to ponder. Were H. habilis and H. rudolfensis both dead ends? Did H. erectus descend from one of these species or a currently unknown member of Homo?

It looks like I have some new stuff to add to my list of hominid fantasy finds for next year.

Ambushing large animals and attacking them with spears is the traditional explanation for why Neanderthals appeared to have the same injuries as rodeo riders. Image: UNiessert/Wikicommons

Neanderthals didn’t ride bucking broncos (as far as we know), but the Stone Age hominids did seem to have one thing in common with rodeo riders: injuries. In 1995, paleoanthropologists Thomas Berger and Erik Trinkaus, now at Washington University in St. Louis, noted that Neanderthals had a disproportionate number of injuries to their heads and necks. The same is true among modern rodeo riders. Just as these cowboys get too close for comfort to angry horses and bulls, Neanderthals’ hunting style—sneaking up on prey and jabbing them with heavy spears—brought their upper bodies within striking distance of large, hoofed animals.

Over the last 17 years, researchers have reassessed the Neanderthal-rodeo rider connection. Recently, in the Journal of Archaeological Science, Trinkaus offered alternative explanations for the trauma patterns.

In the new study, Trinkaus considered the injuries recorded in the bones of early modern humans that lived at the same time as Neanderthals. Early human trauma hadn’t been as well studied as Neanderthal trauma. Statistically speaking, Trinkaus saw no difference between the two species’ wounds; they both suffered a lot of harm to the head and neck. This means ambush hunting may not account for all of these injuries because humans often hurled projectiles at animals while standing back at a safe distance. Recent archaeological work indicates Neanderthals might have done the same thing on occasion. Instead, the source of those injuries might have been violent attacks within or between the two species.

Then again, Trinkaus suggests, Neanderthals and humans might not have had an abnormal amount of upper body trauma after all. He points out that even minor injuries to the head can leave marks on the skull because there isn’t a lot of tissue separating the skin and bone. Arms and legs, however, have fat and muscle that safeguard the bones against more minor flesh wounds. So, anthropologists may not be getting a good estimate of trauma to these parts of the body.

Another factor might also be masking lower body injuries—the mobile lifestyle of Stone Age hominids. Both humans and Neanderthals moved around a lot to find appropriate food and shelter. An individual who couldn’t keep up with the group, due to a broken leg, say, might have been left behind to die, perhaps in places where their bones didn’t readily preserve. (Trinkaus acknowledges that some fossils of old, sick Neanderthals have been found. But although their afflictions, such as arthritis, would have been painful, they wouldn’t have prevented them from walking.)

As Trinkaus shows, there’s more than one way to read Neanderthal trauma. But the small numbers of injured bones left in the fossil record make it hard to know which interpretation is correct.