Ardi: The Missing Link? (Part 1)
I was finally able to sit down and watch the "Discovering Ardi" special last night. It was a very interesting documentary on the work that was accomplished over a period of more than a decade. There were several things which were discussed or stated in the documentary that I would like to address. Before I get into those things, a little background on this discovery is in order.
The full name of the fossil discovered is Ardipithecus Ramidus. It was discovered in Ethiopia in the Middle Awash area. They began discovering some teeth and small bone fragments from many different individuals. How they determined they were different individuals was not mentioned in the documentary. Then they began to discover fragments from the same individual. All of the bones were extremely fragmented and very delicate, to the point that the researchers cemented the bones together and lifted them out in plaster castes. Several years of excavation were conducted before recovering all of the bones which comprise the partial female skeleton that is the current topic of discussion. The researchers then began the painstaking work of removing the bones from the surrounding matrix (dirt) being careful not to damage the bones. They also transported the bones to Japan where they were scanned by a CT machine allowing them to create extremely accurate digital renderings of the bones. The researchers then hired J.H. Matternes to create full-scale reproductions of the fragments. Matternes then drew a complete skeleton followed by a skeleton covered with muscle and then skin, hair, etc. Owen Lovejoy, the project biologist then went to a company to have them create digital videos of how Ardi might have walked and moved through the terrain.
I must state that I think the researchers were very thorough in their work. From watching the documentary, it did not appear that this was hurried or that they were looking to make this “the missing link.” However, some statements made in the documentary caused me to question their conclusions. First, project paleontologist Tim White stated:
“Hominids are incredibly rare. They were rare on the landscape. They had very long life-spans, so few of them die and end up with carcasses on the landscape. They are very smart, smarter than most mammals so you don’t find very many of them trapped in the sediments. So they are extremely rare.”Few of them die and end up with carcasses on the landscape. ..I don’t think he really thought through his statement here, because I’m sure that he would agree if I asked him if all animals eventually die. This puts one hole in his statement concerning why hominids are rare. They didn’t keep living forever or we would be finding them alive today. To be fair, I don’t think that is exactly what he meant. However, the point is still the same—it doesn’t matter if they lived 150 years or 50 years, they would all eventually die. He also claims that they were smarter than most mammals. The problem I have is that this is an assumption inferred back onto hominids because we as Homo sapiens are extremely intelligent and Tim believes that we evolved from hominids. Please hear me, I am not arguing against the point that we evolved from hominids, but I am arguing against this intelligence assumption. We don’t know how smart they were because it cannot simply be inferred from brain size.
The bones did not contain any material useful for dating the bones themselves. To explain how they dated Ardi to 4.4 million years ago, Yohannes Haile-Selassie a project paleontologist explained:
“We don’t really date the bones themselves, so we rely on geologists to give us dates for the rocks that are above and below the fossils that we are finding.”
How do they date these rocks? There were two volcanic rock bands, one above and one below the location they discovered the fossil. They then take samples from these bands and measure the amount of argon gas built up in the rocks. From this they can determine the age of the rocks. I am not familiar with this type of dating. It sounds very interesting and I will be researching this and learning more about it. One interesting point however, the two different tests came back to essentially the same date. At this point, I would think they might have asked to have the tests repeated because there was a lot of sediment between the two bands, several feet of sediment.
I will continue to make more posts on this documentary and fossil find. If you weren’t able to catch the special when it aired this past Sunday night (October 11, 2009), the Discovery Channel has the entirety of it on their website in small clips.
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Millions. The word is Millions, not Billions.
"He also claims that they were smarter than most mammals. The problem I have is that this is an assumption inferred back onto hominids because we as Homo sapiens are extremely intelligent and Tim believes that we evolved from hominids."
For an "extremely intelligent homo sapien" I can't understand what point you are trying to make. It really doesn't take much intelligence for a critter to set themselves apart from ALL other mammals and still come up short when compared to us. Additionally it doesn't take much to be longer lived than the animals you're hunting. Also nit picking on the subjective term "very long Life"
"I know of no evidence that hyenas would have lived 4.4 billion years ago (anyone else?) and there was no evidence given to support this claim when it was made in the documentary. So I am skeptical of this claim."
Its easier to assume the audience of the show has an interest in Evolution so as to not waste time with a supplemental biology education. A simple google search will cure the curiosity of any interested person.
http://en.wikipedia.org/wiki/Hyena#Evolution
"How do they date these rocks? "
Kind of like this:
http://www.google.com/search?q=How+do+they+date+these+rocks
"At this point, I would think they might have asked to have the tests repeated because there was a lot of sediment between the two bands, several feet of sediment."
When you are measuring dates in the 4.4 Million Year range, the margin for error is measured in thousands of years. A lot of sediment can build up during that time. A Layer of volcanic rock does not build up in the same time frame.
You must come from strange place where scientists never ever check their data? Never publish their data and data collection methods.
http://en.wikipedia.org/wiki/Scientific_method
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Science is a social enterprise, and scientific work tends to be accepted by the community when it has been confirmed. Crucially, experimental and theoretical results must be reproduced by others within the science community.
To protect against bad science and fraudulent data, government research granting agencies like NSF and science journals like Nature and Science have a policy that researchers must archive their data and methods so other researchers can access it, test the data and methods and build on the research that has gone before. Scientific data archiving can be done at a number of national archives in the U.S. or in the World Data Center.
Anonymous,
Thank you for the correction on the billion. I have corrected that in the post.
My problem with his statement that hominids were extremely intellegent is that it is an assumtion. He assumes that Homo sapiens evolved from Hominids. There was no proof of this assumption before Ardi's discovery. Even with the discovery of Ardi, intellegence cannot be inferred from skeletal remains. There are some really dumb Homo sapiens and then there are some really brilliant Homo sapiens and they all have roughly the same skull size. That is my point.
As for you citing Wiki, that's not a credible source. It's a good place to go and get an idea about something you've never heard of before, but it isn't academic by any means.
BTW, I explained how they dated the rocks. I am curious if you even read my post or only scanned it for points to criticize?