You and I, and everyone we know, are kin. From the Eskimo to the Aborigine, we are all, literally, siblings. Genetic testing confirms this; each of us is far more closely related to one another, no matter whom you pick to compare, than two chimps in neighboring troops are related to one another. This is one case where the words of the Bible, Talmud, and Koran are backed to the hilt by science: We are all brothers, all one great human family. But it wasn't always so.
Two-million years ago the plains of the Africa were rife with many kinds of walking apes. All of them are fierce looking. But the most dangerous is real a science fiction horror show; a, bloodthirsty super genius, complete with a swollen, bubble-head housing a powerful mutant brain. Muscled like an Olympic swimmer, they're over six feet tall, and could probably give a medium-sized horse a run for his money. This cunning killer wields the blade and club, strikes with ferocity in packs, takes no prisoners, and challenges even the great cats. His descendants will include the most successful, vicious, ruthless, cruel, mutant apes to ever walk the earth: Us.
For the vast majority of the hominid tenure on earth, there were many kinds of walking apes. Each as different and exquisitely varied from species to species as a toy poodle and a coyote are today. And at the dawn of the
Pleistocene, this collection of walking apes was just starting to rise to a glorious peak of hominid diversity.
While our direct ancestors were inventing new tools and possibly using very early forerunners of speech, the Nutcracker men had grown into a robust, specialized eating machine with enormous molars and jaws. In the flesh, these were surely some vicious looking creatures. But odds are they lived relatively quiet lives foraging for tubers, leaves, berries, fruit, and nuts. Represented by the Taung Child, and many finds by Louis and Mary Leakey, these magnificent animals were a highly successful clade of hominids in their own right. But alas, they had specialized in the wrong evolutionary niche. By about 1.3 million years ago, the australopithecines made their last curtain call on the stage of hominid evolution and followed so many other species into the finality of extinction.
(Probably best for them to have never known our modern times. Given our penchant to rape, torture, enslave, subjugate, and slaughter each other, all over minor variations in culture or creed, I shudder to imagine what might have become of any early hominid species at our 'civilized' hands who made it through the ages into the present day)
Louis Leakey looked for a big brained, transitional hominid for decades in the hot dusty plains and narrow rocky valleys of Africa's infamous Olduvia Gorge. He uncovered many interesting hominid remains including the robust australopithecines mentioned above. The Leakey's contribution to paleoanthropology was incalculable. But Louis never found his prize, his missing link; his big-brained hominid. Finally, his health failing, he was forced to give up his quest and retire. His son however would be luckier. In 1972 a team led by Richard Leakey found a fragmented skull. Richard's wife, Meave, spent weeks fiddling with the pieces like a three dimensional jigsaw puzzle. Her patience and skill would pay off. The resulting assembled specimen, called ER 1470, showed a hominid with a braincase twice that of the australopithecine's such as Lucy.
ER 1470 represented a new kind of hominid which is sometimes classified by a splitter as a separate species, Homo Habilis, or Homo Rudolfensis. H. habilis after some initial confusion, was dated to 1.9 million years ago. To a Lumper ER 1470 is merely an early Homo Ergaster. It's a judgment call where one puts the dividing line between those two clades, H. habilis/rudolfensis sort of blends seamlessly into H. ergaster and by 1.5 million years ago we refer to the African hominid with the larger brain capacity as Ergaster. And if we remember our hominid bush, who's to say what it is we're really seeing.
Richard flew to his father's death bed to showcase the new trophy. It is said that Louis Leakey wept with joy and beamed with pride upon seeing the elusive hominid treasure he had sought for so long, and presented now by his own son. It was a story book ending to an epic life fit for a Hollywood movie. A few days later, the legendary father of modern paleoanthropology died; we can only hope the ER 1470 eased his final days just a little. I'd be willing to bet it did.
Rather you're a lumper or a splitter, it's worth noting Habilis/Ergaster features three new morphological traits tying him more closely to modern humans than Lucy's kind. The first concerns the dental arcade.
Look carefully at the above picture. The chimpanzee on the left and Lucy's species A afarensis in the middle, both have a U-shape to their dental arcade. But ER1470 and subsequent Ergasters with even larger brains have a distinctly parabolic shaped dental arcade which is identical to yours and mine.
The second change was in the overall body shape. Lucy had a conical rib cage protecting a long gastrointestinal tract likely necessary to digesting large quantities of tough, fibrous, leaves and roots. The newer hominids lost several yards of that long intestine likely because their diet now included easier to digest meat; it was the birth of the modern waistline. The ancestral brow ridges from Lucy's kind are retained, but the Sagittal Crest is absent.
Lastly, H. ergaster/habilis had a brain capacity of 800 cc or more, as opposed to Lucy's 450 cc (Modern humans average 1200-1400 cc). What was Ergaster doing with this big mutant brain? The evidence suggests Ergaster had become a master stone tool maker, was shunting large game, and may have been using rudimentary speech.
It started with Oldowan Tools over two-million years ago (Left). Mostly simple choppers and flakes likely manufactured by Habilis/rudolfensis. But by 1.5 million years ago, Ergaster had refined his stone chipping skills to produce the beautiful Archeulean Hand Axes (Right). In addition, cut marks are seen on large animals bones at likely butchering sites which fit the edges of these early tools convincingly.
Other changes can only be inferred indirectly, for they leave no solid sign discernible from mere bone and gristle. We cannot know for sure, but it's likely that when our ancestors became hunters stalking live animals on the hot African plains, we lost much of our body hair. This contrast is vividly demonstrated in an artists rendition of what a hirsute Habilis and a less furry Ergaster, may have looked like above. (Images courtesy of The Discovery Science Channel's wonderful special, Walking With Cavemen.)
In 1984 an amazingly complete Ergaster skeleton over a million and a half years old, with a well preserved skull was found near Lake Turkana, in Kenya. The specimen was probably over five feet tall and represented the equivalent of a twelve year old male. He is officially classified as KNM WT 15000. But to paleoanthroplogists he is known more affectionately as The Turkana Boy.
The Turkana skull held a capacity of almost 900 cc, and the post crania was virtually indistinguishable from a modern human with a couple of small exceptions. Micro-analysis of the cervical vertebra indicated that the passage for the spinal cord was too small and lacked the key imprints of specialized nerves associated with modern human speech. Turkana Boy probably did not have the fine motor control over his diaphragm necessary to control breathing/speaking. Yet molds of the interior of the cranial vault, called an endocast, showed a fairly well developed Broca's Area, which is associated with human communication and comprehension of words. Perhaps Ergaster used grunts, hoots or combinations of signs and sounds. But it's plausible that whatever they did possess in the way of communication, it was limited compared to ourselves.
Creationists of course hate fossil hominids and have developed a number of shabby apologetics to deny their transitional status. The most common is to classify them either as mere 'apes'. Or as early humans, sometimes a special class, a made up quasi-clade is produced with the colorful designation 'preflood man' or 'pre-Adamite'. Isn't almost cute when they try to emulate real scientists? Lucy, in answer to yesterday's poll, is most commonly called a 'chimp that walked a little more upright because she was deformed'. Which if you think about it, describes not only Lucy's species A. afarensis, but every other hominid including ourselves!
But when it comes to Habilis, Ergaster, and Erectus, our delightfully duplicitous collection of zany creationists cannot make up their own minds about which is a "just an ape", and which is a "regular human". Could this confusion possibly exist because the specimens in question are transitional (wink)?
At the same time the robust nutcracking Australopithecines were passing into the evolutionary sunset, Ergaster would split into a bewildering array of morphologically distinct hominids. Again we cannot tell for sure if there were many separate species, or just extreme regional variation. But for the purposes of this essay we will group them into three clades.
One stayed more or less unaltered for hundreds of thousands of years. One migrated out of Africa, across the Middle east, and into Asia as far east as Indonesia morphing into Homo erectus along the way.
The last one moved into North Africa, and became Homo Heidelbergensis. H. heidelbergensis, or "bergie" as some like to call him, would eventually dominate much of Africa and move north into southern Europe. And it was possibly bergie that would hit upon the final piece of technology that truly set hominids forever apart from the rest of the animal kingdom. He or she would give us our greatest invention of all time almost one-million years ago. Armed with this novel technology, H. heidelbergensis would colonize ice-age Europe; without it the species would have froze to death in the clutches of the harsh winter forests. The Gift of Fire had finally come to hominids.
Fire would have far more impact than the obvious utility of cooking meat and keeping Pleistocene mega-predators at bay. Huddled around the flames, socializing, working stone, and flirting, human culture was born. There in those ancient circles, clever pack hominids would be transformed by the novel spectral light into something new; they would become the first 'people'. But I can see by the dying embers of my own hearth deep in the dark depths of the DarkSyde Cave that this hominid story will have to wait for another sunrise ...