-Current
Homo Sapiens
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//
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Neanderthal
||
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-1 million yrs
ago
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||
?
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Homo Erectus
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Homo Hablis
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-2 million yrs
ago ||
A. Robustus ||
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// ||===(A.
Garhi ????)
A. Boisei ||
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//--||--------(
?? )
-3 million yrs
ago
\\ || A.
Africanus ||
-------( ?? )
\\ ||
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//-------(disputed
route)
\\ ||
//
//
\\ ||
//
//
-4 million yrs
ago
Australopithecus Afarensis ("Lucy")
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-5 million yrs
ago
(Unknown Transitional Species)
Up until around 1950, the history of humanity was a very sparse and speculative one. The ages of fossils and artifacts were left to simply being known as "before ____ " or "after ____ ". Then paleoanthropologists Dobzhansky and Mayr decided it was time to make a stand to clear up the confusion. They declared that there could not be more than one species of human alive at one time and that everything since the species known as Java Man (Homo Erectus), fit inside Homo Sapiens. While not all scientists used this scheme, most did and the main train of thought in human evolution fit inside its basic ideas. Human evolution then became a steady and gradual change from primitiveness to perfection.
Now, human evolution is thought of in somewhat different ways but the underlying messages are still the same. The dating techniques have improved as have the amount of evidence available (though still very small but larger than before). Scientists now see instead of a steady march to perfection, a series of trial and errors with all-powerful chance arbitrarily trying out new forms. Today we are the only form of Humans on Earth which is now considered more of a rarity, with multiple forms often living next to each other in the past.
The human line is thought to originate in the grasslands of East Africa with a ape-proto human called Austratopithecus Afarensis around 4 million years ago. The decendents of this ape-proto human divided into two separate families....the australopithecus line (boisei and robustus) and homo (Mankind). When exactly this split happened and how it happened is still uncertain. A line called A. Africanus is thought to descend from the A. Afarensis but the remains are only found in South Africa while A. Afarensis is only found in Upper Eastern Africa. Therefore, archaeologists cannot decide whether to place it in the australopithecus line or homo line.
Just this year, a new species of possible human ancestor was discovered in The Middle Awash in Eastern Africa termed, Austratopithecus Garhi. Dating has roughly put it around 2.5 million years ago. Garhi appears to have much the same physical appearance as the austratopithecus but tools and animal bones in the same dirt layer suggest it was using tools in everyday use. The teeth also appear to be a mix of large seed/plant eating types and smaller meat eating type just beginning to form....suggesting a developing mixed diet. This using of tools combined with its small brain size has archaeologists thinking that big brains do not make tools.....rather tools make large brains.
A main sticking point with A. Garhi is that there is only about 500,000 years between it and the first full fledged humans (Homo Hablis). Archaeologists question whether or not this was enough time for the drastic improvements to develop, that it needed, in order to change into Homo Hablis. A. Garhi is still just too ape-like to be so recent on the human family tree. Yet there are suggestions that point to tool use as well. Therefore, archaeologists are still debating on where exactly to put A. Garhi on the human family tree.
Neanderthals
A new study reported in March of 2000 on the Discovery Channel Online website (www.discovery.com) found evidence to support that Neanderthals are not related to modern humans. They are not even in the Human family tree so I had to revise my map above to reflect this.
William Goodwin, a researcher at the University of Glasgow, says that DNA tests done on Neanderthal fossils from the Caucasus Mountains in southern Russia closely match those found in Europe, and that neither of these fossil sets show any trace of human ancestry. It was important that the Russian fossils were found and collaborated the European DNA tests to show that the findings are universal to the Neanderthal population as a whole and not a local aberration.
Still unresolved about Neanderthals is exactly how long they lived with Cro-Magnon man (the first "Modern Human") and exactly why Neanderthals died out. They were stronger and more durable than the modern humans, and yet they were the ones who died out?
A skull found in Croatia is tossing around the ending dates of the Neanderthals. It suggests that a Neanderthal population was living in the area as late as 28,000 years ago. This is 6,000 years later than when the Neanderthals had previously been thought to have died out in Spain. Combined with the new study of their DNA, this would point to a longer amount of time living along-side the Cro-Magnons without much if any genetic interaction - and so are not part of Human Evolution as commonly believed and taught to people today.
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