1859 (October): The Origin of Species was published by British naturalist Charles Darwin, but was not very well received by the scientific community.
1891 (October): Eugene Dubois of the Netherlands, during an obsessive search for evidence of a "missing link" in southeast Asia, found a unique skull he ascribed to "Java Man." (Naturally, he found it on the Indonesian island of Java.) Dubois believed the brain and skull size of a missing link should be precisely half that of modern man's, and precisely twice that of modern chimpanzees. When Java Man's skull didn't fit this model, Dubois changed his hypothesis to fit his evidence and submitted his information to the Dutch government as proof of a missing link. Dubois was ultimately unable to prove that his specimens -- a variety of bones -- came from the same creature, and was consequently dismissed by scientists. Later, however, Dubois' findings were taken a bit more seriously and Java Man was rechristened Pithecanthropus erectus, and was later called Homo erectus.
1912 (December): The "perfect" remains of a missing link were found in Britain, proving Britain's scientific worth equal to Germany's. Charles Dawson discovered Piltdown Man, and was joined in this endeavor by Sir Arthur Smith-Woodward of the British Museum. The Piltdown Man's skull lay unexamined for approximately 40 years before scientists realized it was a hoax. (Someone had placed a human skull with an ape jaw, and coated the bones with some sort of patina to make them appear aged.) It was never proven who the trickster or tricksters were.
1924 (October): Australian physician Raymond Dart in Johannesburg, South Africa was notified of the discovery of a peculiar fossil in a nearby lime quarry. It was actually part of a fossilized brain, somewhat larger than that of a baboon or chimp (as Dart notes himself later) but not large enough to be human. It took Dart until Christmas Eve to painstakingly chisel other fossils, found adjacent to the brain, out of a large chunk of rock. An intact skull and jaw emerged, and appeared to be exactly the opposite of the false Piltdown Man, and therefore opposite of scientists' previous assumptions: rather than an ape-like jaw and a human skull, Dart's specimen had a very human-like jaw and teeth attached to a very ape-like skull. He called it Taung Child; it was later named Australopithecus africanus. Scientists estimated (and still estimate) this specimen to be about 2,000,000 years old.
1953: Piltdown Man was confirmed as a hoax, and scientists began to reconsider some of the discoveries reported since 1912. A new theory soon took shape: brain enlargement was previously thought to be the catalyst leading to the development of modern humans, but in light of new evidence scientists hypothesized tool use must have come first.
1959 (July): Anthropologist and archaeologist Louis Leakey had by this time convinced the scientific community that the missing link, whatever it was and whenever it existed, must have been the first to use tools. Leakey and his wife Mary visited Tanzania to find evidence of this theory when Leakey caught the flu. He was on bedrest when his wife discovered, quite by chance, a very ape-like skull in the same geological layer as stone tools they'd already found nearby. They thought this must be a remnant of humanity's very beginnings, and named it Zinjanthropus boisei. (The specimen was later renamed Australopithecus boisei, but retains the nickname "Zinj.") The Leakeys and their colleagues decided, however, that Zinj's enormous jaw anchored by a skull ridge was indicative of lower intelligence that would have precluded tool use. Later, Mary Leakey gets lucky once more: while stopped on the side of the road to secure a cannister that had come loose in the back of her truck, she spots another exposed skull in the sand. It's in the same geological layer as Zinj and the stone tools, but bears a closer resemblance to modern man. This one is christened Homo habilus, which literally means "handy man," and is a more logical tool-maker. This was evidence of two very different man/ape-like species coexisting in Africa, and a many-branched family tree of human evolution began to take shape.
1974 (November): A team led by American Donald Johanson arrived in Hadar, Ethiopia in search of fame, fortune, and the first human ancestor. Volcanic debris at the northern end of the Rift Valley was radiometrically dated at 3,200,000 years old, which the team found quite encouraging. After going quite some time without finding anything of interest, and having grown tired of paperwork, Johanson and a colleague decided to search nearby gulley. For hours they had no luck, but as the afternoon wore on Johanson convinced his colleague to accompany him into another gulley that had already been thoroughly searched. This time, however, they manage to find the almost-complete skeleton of a creature that would eventually be dubbed Australopithecus afarensis; most know it as "Lucy." It is determined to have been a bipedal tree-dweller, and the old theory is changed yet again: it was neither brain size nor tool use that spurred the first major change in evolution; it was bipedalism. Current thought still reflects this idea -- that bipedalism freed our ancestors' hands for tool use, which prompted brain growth, which in turn led to language and began the intellectual processes that helped make humanity what it is today.
Dubois' Pithecanthropus erectus had a brain about 2/3 the size of modern human brains, and was thought to be "on the verge of becoming human" thanks to their diet. But again, there is no evidence to support such straw-grasping, just as there is nothing to support the assumptions that these creatures were gradually losing their body hair to replace panting with sweating, which in turn allowed for speech.
Additionally, Homo erectus is thought to have been the first to tame fire. If this is true -- as it is assumed to be -- perhaps it would be in our best interest to first answer the question, "Why?" The natural instinct of every other animal is to flee from fire. What, then, inspired Homo erectus to approach it? This sounds more like an argument for intelligent design than for evolution.
Hoaxes like this one reflect very badly upon the scientific community and science in general. To me, this only emphasizes science's religion-like qualities. It also points to the fallibility of scientists' assumptions -- in this case, that a missing link must be equal parts man and ape, ideally with a human skull and brain and an ape-like jaw. What an arrogant assumption to make (that the one item of proof, if it exists, must have had a developed brain and relatively high intelligence); and what an unscientific procedure to follow!
Notice that Dr. Dart compared the skull he found only to baboons and chimpanzees, which excludes almost the entire primate order. It's unknown whether anyone has since carefully compared the skull and fossilized brain to other known species, or whether it's even been considered that Dart's findings (or any other findings) could simply be previously unknown ape species. These findings do not necessarily mean they are human ancestors. Again, this relies on the unfounded assumptions that we must have descended from apes, and that all extinct ape species are somehow related to Homo sapiens.
The multi-branched family tree of human evolution is even more puzzling to me than a unilateral one. I should say, rather, that this widespread faith in it is puzzling. One might argue that every species on earth is interconnected in this way; DNA analysis would support that. We have more in common with dolphins than with other land animals, are quite similar to rodents, and are even genetically comparable to yeast. Indeed, it seems all life on earth is comprised of interstellar material -- "star dust." It would be just as simple to theorize modern humans descended from another group. If our genes connect us to practically all other organisms on earth, why concentrate our efforts on apes? What about marine mammals?
And am I the only one who thinks Mary Leakey's "discoveries" are just a little too convenient?
Professor Leslie Aiello, Head of Graduate School at London's University College, has described Lucy as "basically a chimpanzee," which detracts from the credibility of Johanson and his team. It's unclear, also, whether all the bones they uncovered are from the same creature; they were scattered pretty liberally, and it was conjecture alone that allowed them to be pieced together. Additionally, the circumstances of their discovery strike me as odd: the gulley where Johanson found Lucy had been empty, but was suddenly full of noticeable bones when Johanson arbitrarily decided to revisit the site. The assumption that Lucy was a tree-dweller is somewhat off-putting, too, considering there is nothing to indicate this is true.
Aside from the fact that Lucy's supposed bipedalism requires one's faith in the skeleton's authenticity, the idea that this bipedalism started a chain of events -- tool use and brain growth -- that led to our own development is flawed. Even now we can observe a variety of animals that aren't bipedal, don't have large brains, aren't considered intelligent, and aren't believed to have language, yet they demonstrate organization, the ability to communicate, the ability to plan ahead and solve problems, and even use tools. Consider, for example, dolphins, raccoons, some birds, octopi, and the remarkable Portia spider. Ape to Man, a recent History Channel program about human evolution, claimed, "The ability to organize and communicate -- to improvise a plan -- are all advanced human skills." The implication is that only humans possess these traits, which is demonstrably false.