Why Are Amino Acids Still Found in Fossils?
Why is it that amino acids are still found in fossils and are not broken down after hundreds of million of years? It might be natural to expect that amino acids would be found in fossils. But this is only true if the fossils are not too old because amino acids break down with time. According to the Bible, a global flood that distroyed the whole world, took place less than 5000 years ago. So if we take our hints from Scripture, the fossils that were buried during this flood have only been around for 5000 years. Only when we assume the long ages, that hundreds of millions of years have passed since the fossils were buried, do we find the presence of intact amino acids in fossils incredible.
This question was faced by evolutionists in the 1950s and 1960s, yet no one ever came up with a viable answer.
Amino acids should not be found in fossils. They should survive only a few million years at best (Abelson 1956, 1957). So the question, why are they there? is an extremely important question, it is an enigma!
Because all detectable levels of many amino acids are expected to survive only a few million years, some have suggested that these amino acids found in older fossils are not actually from the fossil itself. The presence of amino acids could very well be a recent contamination.
This idea makes a lot of sense since the fossils are too old, according to the standard paradigm, to have intact amino acids in them. So various research groups set about trying to investigate the possibility that the amino acid presence of older fossils is really a contamination.
Silurian graptolites, which are estimated to be 400-430 million years old by the usual evolutionary conventional age, has been found to contain detectable levels of amino acids that are indeed residual in nature (Florkin 1969). They come from the original proteins when the fossil was buried.
Another group have looked at shells as old as Jurassic, 135-180 million year by conventional age, and found that they contain amino acids that are bound as protein and peptides (Akiyama and Wyckoff 1970). So, since the amino acids are part of the protein and peptide structure of the fossil itself, it is clear that the amino acids are residual in nature. The amino acids came from the fossil when it was buried, not by some contamination process later on when the fossil was buried in the ground.
Because the evidence was so strong and striking, many started to suggest that the amino acids may survive much longer because they are associated within large macromolecules. The protein molecule would create a local environment that would increase the stability of the amino acids. What they were suggesting was that the fossil matrix somehow holds the amino acid molecules together so they do not spontaneously decompose as would be expected on the basis of their binding energies.
As can be seen in the graph to the left or above, the difference in survivability of amino acids that are associated within large macromolecules such as wood, bone, coral and dung, and amino acids that are free in nature; are very small. Most of the points on the graph, whether referring to the free component or an associated component, fit into the same pattern.
I think this is amazing! Because the long ages supported by the evolutionary process is not questioned, researchers are forced to try to come up with unlikely possibilities. They are forced to acknowledge that the amino acids must have survived for hundreds of millions of years so now they have to come up with a reason why they are present!
The graph above illustrates the evidence concerning the racemization of various amino acids suggesting that the variation of amino acid levels found in fossils is due to factors such as heat and not their differences in ages. See my Amino Acid Dating page to hear more.
Another issue, very similar to the question why amino acids are still found in fossils, Concerns DNA. Why is DNA still present in fossils? There is even the presence of DNA and bacterial spores in fossils which are still viable! Bacterial have been grown up from fossils that are thought to be hundreds of millions of years old!
Some Interesting Papers
Amino acid racemization and the preservation of ancient DNA. Poinar HN, Hoss M, Bada JL, Paabo S
Science 1996 May 10;272(5263):864-6
University of Munich, Germany.
The extent of racemization of aspartic acid, alanine, and leucine provides criteria for assessing whether ancient tissue samples contain endogenous DNA. In samples in which the D/L ratio of aspartic acid exceeds 0.08, ancient DNA sequences could not be retrieved. Paleontological finds from which DNA sequences purportedly millions of years old have been reported show extensive racemization, and the amino acids present are mainly contaminates. An exception is the amino acids in some insects preserved in amber.
Predicting protein decomposition: the case of aspartic-acid racemization kinetics. Review
Collins MJ, Waite ER, van Duin AC
Philos Trans R Soc Lond B Biol Sci 1999 Jan 29;354(1379):51-64
Fossil Fuels and Environmental Geochemistry (Postgraduate Institute), NRG, University of Newcastle-upon-Tyne, UK. email@example.com
The increase in proportion of the non-biological (D-) isomer of aspartic acid (Asp) relative to the L-isomer has been widely used in archaeology and geochemistry as a tool for dating. the method has proved controversial, particularly when used for bones. The non-linear kinetics of Asp racemization have prompted a number of suggestions as to the underlying mechanism(s) and have led to the use of mathematical transformations which linearize the increase in D-Asp
with respect to time. Using one example, a suggestion that the initial rapid phase of Asp racemization is due to a contribution from asparagine (Asn), we demonstrate how a simple model of the degradation and racemization of Asn can be used to predict the observed kinetics. A more complex model of peptide bound Asx (Asn + Asp) racemization,which occurs via the formation of a cyclic succinimide (Asu), can be used to correctly predict Asx racemization kinetics in proteins at high temperatures (95-140 degrees C). The model fails to predict racemization kinetics in dentine collagen at 37 degrees C. The reason for this is that Asu formation is highly conformation dependent and is predicted to occur extremely slowly in triple helical collagen. As conformation strongly influences the rate of Asu formation and hence Asx
racemization, the use of extrapolation from high temperatures to estimate racemization kinetics of Asx in proteins below their denaturation temperature is called into question. In the case of archaeological bone, we argue that the D:L ratio of Asx reflects the proportion of non-helical to helical collagen, overlain by the effects of leaching of more soluble (and conformationally unconstrained) peptides. Thus, racemization kinetics in bone are potentially unpredictable, and the proposed use of Asx racemization to estimate the extent of DNA depurination in archaeological bones is challenged.
The kinetics of diastereomeric amino acids with o-phthaldialdehyde.
Meyer MW, Meyer VR, Ramseyer S
Chirality 1991;3(6):471-5 PMID: 1812958, UI: 92256092
Institute of Organic Chemistry, University of Bern, Switzerland.
The kinetics of the reaction of the amino acid epimers L-isoleucine, D-allo-isoleucine, L-threonine, and D-allo-threoninewith o-phthaldialdehyde and mercaptoethanol were determined at 25 degrees C. L-Isoleucine reacts faster than its D-epimer whereas L-threonine reacts slightly slower than its D-epimer. In the case of isoleucine, the consequence can be an allo/iso ratio which in the worst case is 25% too low if these amino acids are quantified by liquid chromatographyand o-phthaldialdehyde fluorescence detection. The effect on dating of fossils by amino acid racemization is discussed.