Lucy's Knee Joint
Letter from Donald Johanson
May 30, 1990
|May 30, 1990|
Mr. Jim Lippard
Department of Philosophy
University of Arizona
Tucson, AZ 85721
Dear Mr. Lippard:
Thank you for your letter of May 17th. It is beyond my intellectual comprehension to understand how creationists think. These are people who feel no reservation whatsoever in totally distorting and misrepresenting simple facts. I appreciate your response to Origins Research and, indeed, you are absolutely correct.
To answer Brown's questions. Yes, it is more than reasonable that afarensis lived in the Hadar region at various times over a 700,000 year period. A proximal femur fragment of an immature individual was found in 1981 at Maka, above volcanic ash dates at 4 Myr. Stratigraphically it was immediately above the volcanic ash, which suggests that its age is close to 4 Myr. At another locality in the Middle Awash of Ethiopia, fragments of a frontal bone from a cranium were found at Belohdelia, in a stratum immediately below the volcanic ash dated at 4 Myr. Australopithecus afarensis has been identified on the eastern shores of Lake Turkana in deposits which are roughly 3 Myr in age (nearly equivalent to some of the later remains from Hadar) and, of course, the very important 3.5-million-year old specimens found at Laetoli, in northern Tanzania, just south of Olduvai Gorge. What this tells us is that afarensis was a highly successful species, geographically widespread, and spanned the time between 3 and 4 Myr in eastern Africa.
The rapid burial of bones at Hadar, particularly those of the "First Family," are related to a geological catastrophe suggesting, perhaps, a flash flood. Bones are fragmented and scattered because individuals fell into a river, or were washed into a river, rapidly transported, broken up, and scattered. These are all products of a depositional process.
It always amuses me when someone like Brown shows his ignorance by suggesting that we submit fragments of the hominids for dating. The fragments of these hominids are, of course, totally mineralized, not containing any organic material. It is impossible to date the fossils themselves and we must rely on the geological context in which they occur. The dates for the Hadar sequence, as well as those for the Middle Awash, have been obtained from the careful dating of volcanic horizons which have been done in at least three independent laboratories. There is no question, whatsoever, of the antiquity of these hominids. Radiocarbon dating goes back, with any degree of certainty, only to about 40,000 years and, of course, cannot--as Brown suggests--be used on fossil specimens.
Thank you for keeping me informed. I look forward to hearing from you in the future.
Donald C. Johanson, Ph.D. President
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