Amber Fossils, T. Rex, and YECs

A collection of 50 million-year-old amber fossils from India were in the news last week (see here). Resin secreted by certain plants can trap and preserve insects, microorganisms, plants, and even (rarely) small vertebrates. Some of these amber fossils have survived hundreds of millions of years.

Seeing these amber fossils reminded me of something I had been thinking about regarding how young earth creationists view science. For them, the earth is about 6,000 years old and everything must be interpreted in that light. They claim that they and scientists share the same facts, but simply differ in interpretation. This strategy is especially effective for scientific findings that superficially support their view.

A perfect example of such a finding was published in 2005 in the journal Science. Paleontologist Mary Schweitzer described the recovery of soft tissue from the femur of a fossilized Tyranosaurus rex. This was a surprising finding that the atheist conspiracy failed to suppress, since the fossil was 65 million years old. Moreover, they were later able to recover and sequence some fragments of collagen protein (not DNA). Nobody knew that such preservation was possible, which is why YECs have had a field day with it. They argue that such preservation isn't possible, which is why this finding supports a young earth. They emphasize how delicate biological molecules are and how quick and pervasive decay processes are. Any other interpretation is just evidence of an unwillingness to face the plain facts. In contrast, mainstream scientists consider the age of T. rex to be pretty solid, supported by an array of evidence. To them, the remarkable preservation of the tissue represents nature teaching us that such preservation is possible under the right conditions, even if unexpected.

Same facts, different interpretation, right?

If Schweitzer had simply cracked open the bone and found soft tissue, we might have a legitimate problem. However, putting it in such simple terms distorts reality. There is a whole discipline of science that studies how fossils are formed, called taphonomy, and there are several types of preservation. Some of these involve replacement of minerals or the infusion of minerals into empty spaces. In the case of T. rex, although the precise mechanism of the preservation is not yet known, minerals obviously played an important role in preventing decay because the tissues had to go through an extensive demineralization process in the laboratory. So although the preservation was unexpected and is not fully understood, it isn't totally detached from prior understanding, either [1]. When considered in the context of all of the supporting evidence for the ancient age of the fossil, it is more parsimonious to conclude that such preservation can occur, rather than that it can't and that all of the supporting evidence is wrong too.

This brings me back to the amber fossils. YECs certainly do not believe that such fossils are millions of years old, but as far as I have seen they don't argue their case on the basis of preservation--that it is impossible--like they have done with T. rex. There seems to be an implied admission that if amber fossils actually were ancient, the degree of preservation would still be believable. It seems, then, that their objection is not to preservation per se. Further, they argue that fossilization can take place rapidly, which undercuts their argument that the T. rex preservation is impossible.

So what about DNA--can it be recovered from amber fossils? It depends on the age. A 2005 review article I found does a nice job of explaining the difficulties of working with ancient DNA [2]. Over the last couple of decades there have been a handful of studies that have claimed to recover DNA from samples tens of million years old, some of them from amber fossils. However, according to the authors there is a theoretical/empirical limit of DNA survival on Earth of about one million years, and in each of these cases the results either could not be replicated or were found to be from contaminants. Their Figure 2 summarizes many of the ancient DNA publications over the last couple of decades. (Click to enlarge. Note that the Y axis is actually log scale.)



The YEC view of the earth is compressed enough to fit well within the theoretical limits of DNA preservation. If scientists can get DNA from a mammoth and Neanderthal, they should also be able to get it from a dinosaur--or certainly a comparably aged amber fossil--without much more trouble. We wouldn't want to say that scientists will never recover such DNA because, just as in the case with T. rex, the possibilities in nature can surprise us. Indeed, subsequent to this review article there have been additional claims of DNA recovery from amber fossils older than the theoretical limit, though the reliability of these reports remains to be determined. However, given that deep time inversely correlates with the technical feasibility of recovering ancient DNA, YECs need to explain the disparity in DNA recovery if deep time is actually an illusion.

They have creative minds. I'm sure they will think of something.



Notes:
(Both articles are freely available.)

1. Mary Schweitzer et al., Soft tissue and cellular preservation in vertebrate skeletal elements from the Cretaceous to the present, Proc. R. Soc. B 22 January 2007 vol. 274 no. 1607 183-197.

2. Eske Willerslev and Alan Cooper, Ancient DNA, Proc. R. Soc. B 7 January 2005 vol. 272 no. 1558 3-16.

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