by Judy Jones
Trouble is, the hominid family tree is starting to look less and less like a tall, dignified elm and more like a squat forsythia with branches shooting wildly in all directions. That’s because a lot of scientists working in the field of paleontology—the study of ancient life-forms—keep (literally) digging up new discoveries: new species, new genera, some of them overlapping, or coming very close. (Ten of the species listed following were not known to exist a decade ago.) What’s more, the dating of the new species is controversial, with some competing scientists basing their claims on limited information and using the skeletons to settle old scores. In the meantime, information continues to trickle in. Who knows? By the time you read this, Fredus flintstoniensis may have turned up.
NAME: Sahelanthropus tchadensis (from Sahel, a region in Africa bordering the Sahara Desert, where the fossils were discovered)
TIME FRAME: Lived 6 to 7 million years ago.
VITAL STATS: Apelike braincase suggests very small brain size (approximately 350 cubic centimeters). But its relatively short and flat face, browridges (the bony structures above the eye sockets), and small canines are typical of later hominids. Lots of debate about whether or not it stood upright.
COMMENTS: A fossil cranium discovered by an undergraduate fossil hunter in 2001 and later identified by Michel Brunet and associates, who nicknamed him—they think he’s a male—“Toumai,” which, in the local Goran language, means “hope of life.” Toumai was important for a couple of reasons. First, he was discovered more than a thousand miles from the sites in East Africa where paleontologists have been focusing most of their work. Second, his age and hominid status throw into question the age of the “missing link”—that elusive common ancestor we share with chimps. He does bolster the argument of scientists who suggest that hominid evolution was way messier than originally thought. In fact, it’s hard to know whether Toumai lies directly in our evolutionary line or if he belongs to a separate branch of the hominid family tree. Or even if he’s a hominid at all; critics insist that Toumai is just a female gorilla in hominid drag. Recently, one of the leaders of the Toumai expedition added fuel to this fire when he accused Brunet of surreptitiously gluing a wisdom tooth to the jawbone.
NAME: Orrorin turenensis (orrorin, “original man” in Tugen, the language spoken where the fossils were discovered)
TIME FRAME: Lived c. 6 million years ago.
VITAL STATS: Hard to say, since there’s not much there. (Fossils consist of fragmentary arms and thigh bones, lower jaws and teeth.) Back teeth are similar to those of Homo sapiens. Limb bones are about one and a half times bigger than Lucy’s (A. afarensis, see following), which suggests that 0. turenensis was about the size of a female chimpanzee. Grooves in the femurs suggest that the species was bipedal and also adapted to tree climbing, but don’t hold us to that.
COMMENTS: Another really old possible ancestor; these fossils were found in western Kenya by Brigitte Senut and Martin Pickford in 2001. For more, see following.
NAME: Ardipithecus ramidus (ardi, “ground” or “floor” in the Afar language, and ramid, the word for “root”); also Ardipithecus kadabba (kadabba, “progenitor” in Afar)
TIME FRAME: Originally dated at 4.4 million years, but recent analysis of A. kadabba dates that species back to 5.2 to 5.8 million years ago. VITAL STATS: Stood approximately four feet tall and weighed about eighty pounds; could walk upright, but probably spent a lot of its time in the trees; marked by humanlike diamond-shaped canine upper teeth (rather than the V-shaped canines of chimpanzees). But generally pretty chimpy-looking.
COMMENTS: OK, take a deep breath. The competition between Orrorin turenensis and Ardipithecus ramidus, not to mention the latter’s older cousin, A. kadabba, is a paleontologist’s version of a barroom brawl—it’s wild, it’s messy, and you never know what they’ll find to slug each other with.
A. ramidus appeared first in 1994, when Tim White, Gen Suwa, and Berhane Asfaw came across its fossils in the Middle Awash region of Ethiopia. The team initially believed that their discovery was part of the Australopithecus genus but then decided that it belonged in its own category. A. ramidus was important for three reasons: First, it was considerably older than the previous discoveries. Second, it lived in a rain forest, which threw into disarray the then-prevalent idea that the hominid’s bipedal adaptation was a result of the expansion of savanna habitats. Finally, because it was not part of the Australopithecus clan, it meant that it was not actually an ancestor of the later species, but was a “sister taxon” with a common (undiscovered) ancestor. All of this meant that A. ramidus wasn’t necessarily the infamous missing link—but it was awfully close.
Then, in 2001, just when everyone was getting comfortable with A. ramidus, anatomist Brigitte Senut and paleontologist Martin Pickford announced that they had discovered a completely new—and older—species, which they called Orrorin turenensis, in Kenya of all places. (Up to that point, anthropologists usually conducted their digs in Ethiopia.) There wasn’t much of this specimen left— thirteen fossils, including a partial femur, parts of a lower jaw, and several teeth—but the age of the fossils demonstrated that if this was indeed a hominid, it was the oldest on record. (At least, at that point; Toumai hadn’t shown up yet.) Not only did the discovery rain on A. ramidus’ parade, but the fact that 0. turenensis may have been bipedal and had a certain size of molars and thick enamel on its teeth showed that it could be a closer relation to Homo sapiens than the Australopithecus. This suggested that Lucy and her gang may have actually been an evolutionary dead end.
As if this weren’t controversial enough, a turf war erupted over excavation rights in the area where Pickford and Senut made their discovery. A Yale anthropologist, Andrew Hill, who’d had a thing against Pickford since their graduate school days at the University of London, leveled the charge. Unfortunately for Senut, Hill had the support of Richard Leakey, part of the famed Leakey family dynasty of anthropologists. (Pickford and Leakey had their own turbulent history, of which we’ll spare you the details.) Things got so nasty that the Kenyan authorities (on Leakey’s suggestion) arrested Pickford and threw him into prison for a few days. Since then, Orrorin turenensis has been treated with at best suspicion and, at worst, contempt by much of the paleontological community.
Now, another fly in the ointment: In 1997 and 2001 more fragmentary fossils were discovered in Ethiopia that were similar to—but a wee bit older (at about 5.8 million years ago) and more apelike—than the 4.4-million-year-old A. ramidus. These were initially named Ardipithecus ramidus kadabba, but scientists eventually decided that these new fossils were not a subspecies at all and were likely the direct ancestor of A. ramidus. As a result, these fossils were categorized as a new species in their own right: Ardipithecus kadabba. And if your head isn’t swimming yet, there are other scientists who claim that Orrorin turenensis and Sahelanthropus tchadensis are not really separate genera at all, but should be included in the Ardipithecus family.
NAME: Australopithecus anamensis (anam means “lake” in the Turkana language)
TIME FRAME: Something like 4 million years ago.
VITAL STATS: Most definitely a biped. Still a very primitive cranium, but a more advanced, humanlike body. An interesting mix of the chimp (big canines, little brain) and the genus Homo (strolling about on two legs, thick enamel on its teeth).
COMMENTS: Odd history on this one. The initial find of A. anamensis—part of an upper left arm—was actually discovered by a Harvard University expedition way back in 1965. Then, except for a single molar in 1982, nothing else was found until a team organized by Maeve Leakey (wife of Richard Leakey) made a number of fossil discoveries in the late Eighties and early Nineties in the Kanapoi region in Kenya. Interestingly enough, there are certain physical components of A. anamensis that seem to be closer to the Homo genus than the later Australopithecus afarensis (see below). Perhaps yet another argument for the “branch” theory of hominid development…
NAME: Australopithecus afarensi
s (from Afar, a region in Ethiopia)
TIME FRAME: Between 3 and 3.9 million years ago.
VITAL STATS: Brain of about 400 cubic centimeters in a very apelike skull (though with more humanlike teeth). Certainly walked upright, but even so could probably be confused with a chimp in the dark, especially given those long hairy arms. Stood only about three or four feet tall.
COMMENTS: In 1974, in Ethiopia, anthropologist Donald Johanson found a female skeleton he dubbed Lucy, after the Beatles song “Lucy in the Sky with Diamonds.” Scientists figure she was about twenty-five years old when she died. Lucy captured the imagination of journalists for a long time, until she was overshadowed by older fossils in the 1990s. Part of her appeal lies in her completeness; unlike many other fossilized discoveries, more than 40 percent of Lucy’s remains were found.
NAME: Australopithecus africanus
TIME FRAME: Between 2 and 3 million years ago.
VITAL STATS: Similar to A. afarensis, but with a slightly bigger body. Cranium is a bit bigger, too—between 420 and 500 cubic centimeters. Though this is bigger than a chimp’s brain and could suggest some analytical skills, nobody really thinks that A. africanus was reciting the Gettysburg Address.
COMMENTS: One of the earlier paleontological finds, this one was the result of an arduous seventy-three-day dig by the famous anthropologist Raymond Dart in 1924 in South Africa. Named the Taung Child after the area where he was discovered, this three-year-old specimen caught the world’s attention because he was so obviously somewhere between an ape and a human. He also blew apart the idea—commonly held up until that point—that Asia was the home of the origins of man.
NAME: Australopithecus garhi (garhi, “surprise” in the Afar language)
TIME FRAME: 2.5 million years ago
VITAL STATS: Still has a pretty teeny brain. However, A. garhi ’s teeth, which are really quite large, along with its humanoid humerus and femur, suggest that it could be a middle mark between the gracile and robust Australopithecus families (just as you fear, we’re going to explain that in a moment) or even a link between its cousin A. afarensis and early members of the Homo genus. But don’t quote us on that.
COMMENTS: Calling this one a surprise is an understatement; garhi is quite controversial, since its existence throws into disarray a lot of previously held assumptions about the other members of the Australopithecus group (especially A. africanus, which could be an evolutionary dead end). Biggest debate stems from the fact that fossils of animal bones discovered nearby bore cuts from stone tools. This would mean that A. garhi is the first tool user and also that such behavior predated increases in brain size. (The oldest stone tools, thought to be about 2.6 million years old, were also discovered nearby.)
NAME: Australopithecus aethiopicus
TIME FRAME: Somewhere between 2.6 and 2.3 million years ago. VITAL STATS: Interesting mix of the primitive and the advanced. Small brain size (410 cubic centimeters) and other parts of the skull are reminiscent of A. afarensis. Large, flat face with no forehead. Huge teeth, along with evidence of powerful chewing muscles suggests that this species ate grains and other tough foods.
COMMENTS: Known mostly by the “Black Skull,” a fossil discovered in 1984 in the Lake Turkana area of Kenya. Scientists generally can’t make up their minds whether to classify this in the Australopithecus or Paranthropus genus, since it is clearly on the border between the gracile species described previously (known for their lighter build, particularly in the skull and teeth) and the more robust (heavier-skulled, with larger teeth) species following, which many researchers classify as Paranthropus.
NAME: Paranthropus or Australopithecus robustus (Take your pick.)
TIME FRAME: About 2 to 1.5 million years ago.
VITAL STATS: Similar body to A. africanus (see previously), but the brain’s definitely getting bigger (530 cubic centimeters). Considerable difference in body size between females and males, with males standing about four feet four inches tall and weighing about ninety-two pounds, and females standing three feet seven inches and coming in at a svelte seventy-one pounds.
COMMENTS: Nobody’s sure of the exact relationship between the robust species. This one was discovered in South Africa by Robert Broom in 1938. Along with “Nutcracker Man” (below), it is assigned to the genus Paranthropus by some researchers, and to Australopithecus by others. Once again, this species demonstrates a powerful chewing mechanism, made for eating tough and coarse foods, which suggests these guys might have been the first vegetarians. This would make sense, since at this point we’re on the verge of an ice age, so certain kinds of food might have been getting scarce. There is some speculation that the species may have been using tools as well, since animal bones found with the fossils might have been used for digging, and P. robustus’ hand bones are developed enough to suggest some fine motor skills.
NAME: Paranthropus or Australopithecus boisei (“super robust”)
TIME FRAME: 2.1 to 1.1 million years ago.
VITAL STATS: Similar in many ways to P. robustus, but beefier, standing as tall as five and a half feet and weighing as much as 150 pounds. Had even bigger teeth (he was known as the “Nutcracker Man”), with some molars measuring two centimeters from front to back. This suggests that these guys were still vegetarians, specializing in nuts, roots, and tasty tubers.
COMMENTS: The first P. boisei specimen was discovered in 1959 in Tanzania—a first for that area—by Mary Leakey. (Yes, that would be Richard’s mom—are you seeing a pattern here?)
NAME: Homo habilh (“handy man”)
TIME FRAME: Somewhere between 2.4 and 1.5 million years ago.
VITAL STATS: Four and a half to five feet tall, 64 to 100 pounds, brain volume about 750 cubic centimeters. Higher forehead indicates developed frontal and temporal lobes, and thus greater reasoning powers. Possibly capable of basic speech.
COMMENTS: Handy man clearly used tools—thus his name. Was generally smaller than his australopithecine cousins and had smaller teeth, so he ate just about anything he could get hold of, including meat. However, H. habilis was too small to take on big game, so his bigger brain came in handy to outsmart leopards.
NAME: Homo georgicus (named after Georgia, the ex-Soviet country where it was found)
TIME FRAME: About 1.8 million years ago.
VITAL STATS: A transitional species between H. habilis and H. erectus.
COMMENTS: Discovered in 2002, this specimen challenges the “out of Africa” mind-set. Before H. georgicus, hominids—specifically, the highly intelligent (comparatively speaking) H. erectus—were thought to have ventured into Europe no earlier than 1 million years ago. H. georgicus blows that theory out of the water.
NAME: Homo erectus (“erect man”)
TIME FRAME: From 1.8 million to 300,000 years ago.
VITAL STATS: Nearly our size, with smaller jaw and larger brain (varying between 750 and 1225 cubic centimeters) than its predecessors. Probably stronger than modern humans. Despite its name, not the first to stand upright, but a more graceful walker than modern humans, whose frames have had to compensate for big-brained infants.
COMMENTS: A very Atkins-like protein-rich diet meant a larger brain and a smaller gut than the species that came before it. The good news: H. erectus produced the first hand axes, and was the first to make use of fire and shelter—the rude beginnings of culture. The bad news: Some of the skull fossils discovered revealed that the brains had been removed prior to death, suggesting that H. erectus might have been a cannibal.
NAME: Homo ergaster (“work man”)
TIME FRAME: 1.7 to 1.5 million years ago.
VITAL STATS: Despite differences (different-shaped brows, smaller brains), this African species is pretty much the same as the Eurasian erectus. In fact, some scientists classify H. ergaster as an earlier version of H. erectus, but it’s a bit of a chicken-and-egg situation.
COMMENTS: As the name suggests, this species had a pretty extensive toolbox. Notable for the 1984 find of Turkana Boy, an a
lmost complete skeleton of a lanky eleven-year-old adolescent. Considered the first hominid with a conscience, since a female H. ergaster was found to be in the advanced stages of a nasty bone disease, meaning that other members of the tribe must have looked after her.
NAME: Homo sapiens (“wise man”)
TIME FRAME: From about 600,000 to 100,000 years ago.
VITAL STATS: Flatter faces, bigger brains (about 83 percent the size of ours), but still had bulging browridges.
COMMENTS: Also known as Homo heidelbergensis, from Heidelberg, Germany, where the first fossils were found back in 1907. No miracle makeovers here—H. erectus segued slowly into H. sapiens. He hunted, cooked his food, made wooden tools, and may have launched language. (The word sauté did not appear for several hundred millennia, however.)
NAME: Homo sapiens neanderthalensis (after the Neander Thal—or “valley”—of Germany, where they were first discovered)
TIME FRAME: From about 250,000 to 30,000 years ago.
VITAL STATS: Not hunched brutes, as popularly believed; the first skeleton, found in 1856, just happened to be that of a big, arthritic specimen. They were actually powerfully built, short (average male height was five feet six inches) and very solid; probably an adaptation to the nasty Ice Age climate.
COMMENTS: Generally accepted as a subspecies of H. sapiens, though believed by some to be a separate species, Homo neanderthalensis. Probably the first humans to conduct funerals, as evidenced by remains of flower pollen at a Neanderthal gravesite. The Neanderthals disappeared mysteriously about 35,000 years ago, to be replaced by Cro-Magnons, a hipper subspecies of H. sapiens responsible for the celebrated cave paintings in Lascaux, France. Nobody is sure whether the Neanderthals died out, were killed, or simply intermarried themselves into oblivion. Or maybe we all have a trace of Neanderthal in us and just don’t know it.
