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Lucy, a partial Australopithecus afarensis skeleton, is one of the most famous hominid fossils ever found in Ethiopia. Image: 120/Wikicommons

Ethiopia may well deserve the title Cradle of Humankind. Some of the most famous, most iconic hominid fossils have been discovered within the country’s borders. Ethiopia can claim many “firsts” in the hominid record book, including first stone tools and the first Homo sapiens. Here’s a look at the country’s most important hominid finds.

Omo I and II (1967-1974): While excavating the Kibish Formation near the Omo River, Richard Leakey and his colleagues uncovered a partial skull and skeleton (Omo I) and a partial skull (Omo II) that are still thought to be the oldest examples of Homo sapiens. Dating to 195,000 years ago, Omo I has several features that clearly place it within our species, including a flat face, high forehead and prominent chin. Omo II, on the other hand, looks more primitive. While some researchers suggest its thicker skull and sloped forehead preclude it from being a true modern human, others say those features were probably within the range of variation for early H. sapiens.

Lucy (1974): While searching a dry gully at the site of Hadar, paleoanthropologist Don Johanson noticed a slender arm bone sticking up from the ground. He thought it belonged to a hominid. Then he noticed a thigh bone, some bits of a spine, a pelvis and some ribs. Eventually, Johanson and his colleagues unearthed approximately 40 percent of a hominid skeleton dating to roughly 3.2 million years ago. Named Lucy after the Beatles’ “Lucy in the Sky with Diamonds,” the skeleton is officially known as AL 288-1 and is arguably the most famous hominid fossil ever found. But it took a while for Johanson, with the help of paleoanthropologist Tim White, to figure out what Lucy was—Australopithecus afarensis—and her place in the human family tree. (For a firsthand account of Lucy’s discovery and the analysis of her remains, you probably can’t find a better book than Lucy: The Beginnings of Humankind by Johanson and Maitland Edey, even if some of the science is out of date.)

First Family (1975): Just a year after discovering Lucy, Johanson’s team got lucky again, finding a jumble of more than 200 A. afarensis fossils at the site of Hadar. The collection—representing as many as 17 individuals—was dubbed the “First Family” (official name: AL 333). Because the fossils contained both adults and youngsters, the First Family is a snapshot of variation within A. afarensis and offers a look at how an individual within the species might have grown up. Anthropologists are still trying to figure out what led to the demise of such a large group of hominids. A catastrophic flood is one theory; death by over-eager carnivores is another.

Australopithecus garhi (1990, 1996-1998): Paleoanthropologists Berhane Asfaw and Tim White found a partial skull and other pieces of the 2.5-million-year-old species known as A. garhi in 1990 at the site of Bouri. Since then, no additional fossils have been unearthed (or, at least, matched to the species). Not much is known about A. garhi. Based on the length of a thigh bone, the species may have had slightly longer legs, and therefore a longer stride, than Lucy’s kind. Given the species’ age and where it was found, A. garhi may have been the hominid to make the oldest known stone tools (described next).

Oldest Stone Tools (1992-1994): At 2.6 million years old, the stone choppers, or Oldowan tools, at the site of Gona are a few hundred thousand years older than any other known stone tool. But the Gona tools’ status as earliest stone tool technology was recently challenged by another Ethiopian discovery. In 2010, archaeologists claimed that roughly 3.39-million-year-old mammal bones from Hadar contained scratches that could have only been made by a stone tool, implying stone tools were an even earlier invention than scientists had thought. Other researchers remain unconvinced that the markings were made by hominid butchering. And since no actual stone tools were found along with the bones, the Gona artifacts’ title of earliest known stone tools is still safe.

Ardi (1992-1994): Older than Lucy, Ardi is the most complete skeleton of an early hominid. The first pieces of the 4.4-million-year-old Ardi were uncovered in 1992 by one of Tim White’s graduate students, Gen Suwa, in the Middle Awash Valley. White and his colleagues then spent more than 15 years digging Ardi out and analyzing the skeleton. The hominid did not look like Australopithecus, so the researchers gave it a new name: Ardipithecus ramidus. Although the species walked upright on two legs, its form of bipedalism was quite different from that of modern people or even Lucy. Its discoverers think Ardipithecus represents an early form of upright walking and reveals how apes went from living in the trees to walking on the ground.

Ardipithecus kadabba (1997): Yohannes Haile-Selassie of the Cleveland Museum of Natural History unearthed hand, foot and other bones in the Middle Awash Valley that looked a lot like those of Ar. ramidus—only the bones were almost a million years older, with an age of about 5.8 million years. Teeth found in 2002 suggested the more ancient hominids deserved their own species: Ar. kadabba. It remains one of the earliest known hominid species.

Dikika Child (2003): From the site of Dikika comes the fossil of an approximately 3-year-old A. afarensis child dating to 3.3 million years ago. Sometimes called Lucy’s baby or Selam, it’s the most complete skeleton of an early hominid child, including most of the skull, torso, arms and legs. The fossil’s discoverer, Zeresenay Alemseged, of the California Academy of Sciences, and colleagues say the fossils suggest A. afarensis grew up quickly like a chimpanzee but was beginning to evolve slower growth patterns like those of modern humans.

Herto fossils (2003): Even if the Omo I and II fossils turned out not to be members of H. sapiens, Ethiopia would still be home to the earliest known members of our species. A team led by Tim White discovered three 160,000-year-old skulls in the Middle Awash Valley. Two belonged to adult H. sapiens while the other was of a child. Due to some features not seen in modern populations of humans, White and his colleagues gave the skulls their own subspecies: H. sapiens idaltu.

Australopithecus anamensis (2006): A. anamensis, the earliest species of Australopithecus, was already known from Kenya when a team led by Tim White of the University of California, Berkeley discovered more fossils of the species further north in Ethiopia’s Middle Awash Valley. The collection of roughly 4.2-million-year-old fossils is notable because it includes the largest hominid canine tooth ever found and the earliest Australopithecus femur.

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.

This jaw from Kent’s Cavern is about 41,000 years old. That makes it the oldest modern human fossil in England and one of the oldest ever found in Europe. Image: Chris Collins/Natural History Museum, London and Torquay Museum

The London Olympics are a great excuse to talk about England’s hominid history. Current evidence suggests that hominids reached Great Britain by at least 800,000 years ago, when the island was connected to mainland Europe. Since then, as many as four different hominid species have lived there. Coming and going in response to climate change, hominids probably fled England during extreme cold times when glacial ice covered the area. Sometime between 450,000 and 200,000 years ago, catastrophic flooding of a glacial lake eroded the land bridge connecting Great Britain and Europe and changed the drainage patterns of the region’s rivers. As a consequence, during warm periods when polar ice sheets melted and sea levels rose, the land bridge was transformed into a channel. This barrier probably explains why hominids are absent from the fossil record 180,000 to 60,000 years ago. It wasn’t until 12,000 years ago that the ancestors of modern Brits finally arrived on the island and stayed for good.

With that mini-review in mind, here are five of England’s most important human evolution discoveries.

Happisburgh (~780,000 years ago): This site, about a three-hour drive northeast of London, contains England’s earliest evidence of hominids. In 2010, archaeologists announced in the journal Nature that they had found flaked stone tools dating to between 990,000 and 780,000 years ago, when Great Britain was connected to mainland Europe. Fossils and climate data suggest the environment was much like modern southern Scandinavia, home to coniferous forests. No hominid fossils have been found there yet. But back in 2010, paleoanthropologist Chris Stringer of the Natural History Museum in London told Nature News that these hominids might have been members of the lesser-known species Homo antecessor.

Pakefield (700,000 years ago): Before the discoveries at Happisburgh, this was the oldest archaeological site in England. About an hour south of Happisburgh, the younger Pakefield find consists of more than 30 stone tools, and the environmental data suggests the hominids here experienced a warm, seasonally dry Mediterranean climate, researchers reported in Nature in 2005.

One of the stone tools from Pakefield. Image: Harry Taylor/Natural History Museum, London

Boxgrove (500,000 years ago): On England’s southern coast in the 1990s, anthropologists recovered what are the oldest hominid remains ever found in that country: a shin bone and two teeth dating to half a million years ago. Researchers think the bones belonged to Homo heidelbergensis, the species that many anthropologists consider to be the common ancestor of modern humans and Neanderthals. Stone tools and fossils at the site reveal the hominids butchered horses, deer and rhinos. Wolves, lions and hyenas also lived nearby (PDF).

Swanscombe (400,000 years ago): Between 1933 and 1955, amateur archaeologists discovered three separate pieces of the same female skull at a gravel quarry in Swanscombe. The skull is thought to be that of an early Neanderthal (although the skull’s age and species status have been questioned.) Less than an hour east of London, the Swanscombe site is now a historical park.

Kent’s Cavern (~41,000 years ago): In 2011, researchers reanalyzed a partial upper jaw and teeth discovered in 1927 in Kent’s Cavern in southwestern England. Originally thought to be 35,000 years old, the fossils are actually about 41,000 years old, the researchers reported in Nature. The older date makes these the oldest modern human (Homo sapiens) bones found in England and among the oldest ever found in Europe. Today, tourists can visit the cavern (and even get married there).

If this isn’t enough British hominid history for you, try reading Chris Stringer’s Homo britannicus.