Thirty years ago, paleoanthropologists Donald C. Johanson and Richard Leakey got into a heated quarrel - on television - over human origins at the American Museum of Natural History in New York. Johanson had discovered the famous australopithecine Lucy, and he contended that Lucy represented a human ancestor. Leakey, who grew up on fossil digs in Africa and whose team discovered Turkana Boy in 1984, argued that humans dated back before the australopithecines, and therefore Lucy did not fit into the lineage of humans.
While the debate ended without bloodshed, it is remembered for the passion of its participants. Thirty years later, the Arizona State University Institute of Human Origins is celebrating its anniversary during 2011–2012 with the theme of “Becoming Human: 30 Years of Research and Discovery.” Johanson and Leakey returned to the American Museum of Natural History to discuss the fossil evidence for human ancestry, this time with far more humor and far less venom. While the two have had their differences, they agree on one thing – that human beings evolved from apes millions of years ago.
Paleoanthropology is the fascinating study of ancient humanity through the excavation of bones and evidences of human culture from thousands of years ago. Of course, the majority of paleoanthropologists long to find out not only about ancient humanity, but also about the descent of mankind from the apes. This motivation to find missing links colors every new hominid discovery. From Lucy to Turkana Boy to Peking Man, paleoanthropologists believe they have found pieces of humanity's ancient family tree - the links between the apes and modern day humans. But, do any true missing links exist? Or is tree of ancient humanity really just a pair of two separate bushes – one of apes and one of humans?
We cannot begin to go through all the hominid finds made over the past 150 years in this short article, but we can touch on the most familiar.
The term "Neanderthal," still brings to mind a thick-skulled knuckle dragger with far more brawn than brain power. The Neanderthal man had heavy bones and those distinctive heavy eyebrow ridges. His chin was smaller and rounded, the center of his face jutted forward, and his skull was low and elongated. It was easy to portray him as a primitive man, closer to the apes. Today, though, scientists generally agree that Neanderthal was a highly intelligent, creative, true human being. In fact, Neanderthal had an average cranial capacity (and therefore brain size) of 1,485 cc, with a range of 1,245–1,740 cc, slightly larger than the modern human average of 1,350 cc. While greater cranial capacity doesn't necessarily equal higher intelligence, it does look good on Neanderthal's resume.
In his book Buried Alive, orthodontist Jack Cuozzo describes the poor reconstruction of certain original Neanderthal skulls to make them appear more ape-like and "primitive." For example, he argues that the Le Moustier specimen was reconstructed in a way that made the jaw appear more ape-like than it would have been naturally. Cuozzo also makes the very interesting argument, based on his knowledge of jaw and tooth growth, that it appears that Neanderthals lived to be several hundred years old.
According to Live Science November 15, 2006, "[E]xcavations and anatomical studies have shown Neanderthals used tools, wore jewelery, buried their dead, cared for their sick, and possibly sang or even spoke in much the same way that we do. Even more humbling, perhaps, their brains were slightly larger than ours." There is no question that the Neanderthal was a fully functioning human.
Many different hominid discoveries fall into a broad Homo erectus classification. These humans include Peking Man, Java Man, and early African Homo ergaster specimens like Turkana Boy. H. erectus was a smaller person, with an average cranial capacity of 973 cc. This falls into the low end of modern human range, which is about 700–2,200 cc according to Molnar's Races, Types, and Ethnic Groups (1975). H. erectus bodies are generally described as very much like modern humans, though thicker boned. It is the H erectus skull that has been particularly classified as more primitive. The large brow ridges and flat, receding forehead, the smaller, forward-jutting jaw and large teeth all are considered primitive characteristics - as is the long, low-vaulted cranium and occipital torus.
Yet, these are features that Neanderthal also has, and Neanderthal is regarded as fully human. It can be argued that Homo Erectus is in fact just a small version of Neanderthal.
Harry Shapiro writes in his 1974 book Peking Man, (George Allen & Unwin Ltd, London, p. 125):
'But when one examines a classic Neanderthal skull, of which there are now a large number, one cannot escape the conviction that its fundamental anatomical formation is an enlarged and developed version of the Homo erectus skull. As in Homo erectus, it has the bun-shaped protrusion in the occiput, the heavy brow ridge, the relatively flattened crown that from the rear presents a profile like a gambrel roof. Its greatest breadth is low, just above the ears, and the absence of a jutting chin is typical.'
He wrote that back when Neanderthals still had a fairly brutish reputation, but that doesn't change the basic implication. H. erectus has generally been considered a couple of steps closer to the apes than we are, but if he was rather like a smaller version of the Neanderthal, his features should not necessarily be considered primitive. In fact, modern day Australian Aborigines also display many of these features, and they will be quick to assure us that yes, they really are humans too.
H. erectus finds show he had the intelligence and technology of any humans stuck out in the wilderness. For instance, stone tools found with Peking Man show that he cut down trees, trimmed his wooden clubs and dismembered the animals caught as food. Peking Man also made use of fire. It appears that in the search for missing links, H. erectus has too quickly and erroneously placed in the less-than-fully human category.
The first australopiths were uncovered by Mary Leakey in Tanzania in 1959, and the Leakey family has uncovered many more specimens there in the Olduvai Gorge since. The name australopithecine means "southern ape" and Lucy (Australopithecus afarensis), discovered by Donald Johanson in 1974, was likely about as bright as chimpanzees today. The estimated cranial capacity of A. afarensis was between 375 and 540 cc and it has the large jaws and small brain cavity of apes. Lucy also has the short legs, long arms and pot belly of an ape. The thing that excites paleoanthropologists is some analysis that argues Lucy walked upright.
Yet, as we noted in our article on Ardi in October, 2009, Anatomist Dr Charles Oxnard used multivariate analysis to show that Lucy's big toe was opposable, just like in chimpanzees. B.G. Richmond and D.S. Strait also reported in Nature in 2000 that Lucy's wrists indicated she was actually just a knuckle-walker like other apes. Lucy is often portrayed with human feet and standing upright, but not necessarily because of her actual morphology. Human footprints have been found in the hardened ash at Laetoli, near where Lucy was found. The footprints were dated to the time of Lucy using K/Ar testing, and since most evolutionists believed that humans and Lucy did not co-exist, they have concluded that Lucy must have made the prints herself.
Cro Magnon was an ancient physically modern man.
Toumai (Sahelanthropus tchadensis) was an ancient ape that is dated older than Lucy but with features "younger" than Lucy's. Definitive conclusions on Toumai are hard to come by.
Ardi (Ardipithecus ramidus) was an ape, long extinct, whose skeletal remains were horrible crushed and therefore difficult to interpret objectively.
Homo habilis is arguably an invalid taxon made up of a mixture of fossils from both apes and humans
New hominid remains are found every year, always with much fanfare. Rather than clearing up the question of human ancestry for evolutionists, though, these always seem to just add another twig on the already-twiggy branches of either humans or apes. They have yet to provide a true trunk that links the two branches together.