The Top Ten Human Evolution Discoveries from Ethiopia
October 10, 2012 (Smithsonian) — 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find a better book than Lucy: The Beginnings of Humankind by Johanson and Maitland Edey, even if some of the science is out of date.)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 ofAustralopithecus, 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.