|Wesley R. Elsberry
Joined: May 2002
Even Further Out on a Limb...
Joe Carter lit into PZ Myers over some harsh words PZ had for Stephen Meyer's arguments in Meyer 2004.
Carter doesn't pussyfoot around in making the broad claim:
While I appreciate the effort, Dr. Myers has only shown that even when he bothers to check the “esoteric literature”, he still remains unable to adequately address Meyer’s article. Let me clarify that I am not claiming that Meyer’s review is free of error or that it is a model of scholarship. My main contention is only that the critics at PT have failed to offer a persuasive or even relevant rebuttal. This latest effort only provides further evidence for my case:
What's so funny about this grandstanding of Carter's is how completely he falls on his face when actually dealing with the first part of Myers' critique.
Since I don't have multi-level quoting, I'll use the old BBS standby of prefixing initials to indicate who said what.
SCM> For over three billion years, the biological realm included little more than bacteria and algae (Brocks et al. 1999).
PZM> Uh-oh. This one is very misleading. Brocks et al. is a paper about molecular fossils: they analyzed trace materials in ancient rocks, looking for the chemical signatures characteristic of different domains of life. While it is talking about trace molecules left largely by bacteria, it makes no statement about the absence of other organisms, and explicitly states that the phylogenetic position of the eukaryotes responsible for the lipids they found is unclear.
JC> The claim that Meyer’s is being “misleading” is applicable only if PZ means that the “little more than bacteria and algae” excludes less developed forms of life.
And Carter is already off in the weeds. The claim that Meyer is being misleading stands if the cited reference does not support the claim that Meyer is making, which can be the case not only if more complex life is excluded, but also if Meyer and Brocks et al. don't agree on timing.
JC> While it is true that the article makes no mention of the “absence of other organisms” it does say:
Brocks et al.> Microfossils 11), stromatolites (2), and sedimentally carbon isotope ratios (3) all indicate that microbial organisms inhabited the oceans in Archcan times [>2500 million years ago (Ma)]. But these lines of evidence are not very informative about what these microbes were or how they lived. Potentially, a better insight into primordial biological diversity can be obtained from molecular fossils derived from cellular and membrane lipids ("biomarkers"). Although such soluble hydrocarbons were first extracted from Archean rocks more than 30 years ago, their significance was generally discounted after amino acids of recent origin were found in the same rocks (4). Prevailing models of thermal maturation dictated that complex hydrocarbons should not survive the metamorphism experienced by all Archcan terrains. However, indications of greater hydrocarbon stability (5) and observations of oil in Archean fluid inclusions (6) suggest that these maturation models are unduly pessimistic and that biomarkers could indeed be preserved in low-grade Archean metasedimentary rocks. Furthermore, systematic sampling strategies, improved analytical techniques, and greater geochemical knowledge (7} should make their recognition easier and their interpretation more rigorous. We now repo,1 molecular fossils in late Archcan shales that have suffered only minimal metarmorphisre. These molecular fossils reveal that the Archeart biota was considerably more complex titan currently recognized and that the domains Eucarya and Bacteria were already extant. [emphasis added]
JC> The article makes no mention of organisms that more advanced than microbes. In fact, as Brocks says in his final sentence, “The discovery and careful analysis of biomarkers in rocks of still greater age and of different Archean environments will potentially offer new insights into early microbial life and its evolution.”
JC>Does PZ know of evidence for more advanced life forms during this period?
PZ doesn't need to provide evidence for more advanced life forms in the Archean period that is the subject of the quotation Carter provides from Brocks et al..
That's right, Brocks et al. is dealing with stuff that is way, way old. They are dealing with things that are older than 2.5 billion years old. That's how to parse that technical note of "[>2500 million years ago (Ma)]" that was in the quote Carter provided.
Let's look at Meyer 2004 again:
The Cambrian explosion represents a remarkable jump in the specified complexity or “complex specified information” (CSI) of the biological world. For over three billions years, the biological realm included little more than bacteria and algae (Brocks et al. 1999). Then, beginning about 570-565 million years ago (mya), the first complex multicellular organisms appeared in the rock strata, including sponges, cnidarians, and the peculiar Ediacaran biota (Grotzinger et al. 1995). Forty million years later, the Cambrian explosion occurred (Bowring et al. 1993). The emergence of the Ediacaran biota (570 mya), and then to a much greater extent the Cambrian explosion (530 mya), represented steep climbs up the biological complexity gradient.
Meyer is deploying the Brocks et al. study as establishing that life consisted of "little more" than bacteria and algae right up to 570mya. But as Joe has established, the period Brocks et al. discuss is from 2.5 billion years ago and older. That leaves a mere 1.93 billion years of life's history intervening between what Brocks et al. were talking about and where Meyer implies that they left off. I'd say that was pretty misleading.
Let's review Carter's braggadacio at the outset one more time:
While I appreciate the effort, Dr. Myers has only shown that even when he bothers to check the “esoteric literature”, he still remains unable to adequately address Meyer’s article. Let me clarify that I am not claiming that Meyer’s review is free of error or that it is a model of scholarship. My main contention is only that the critics at PT have failed to offer a persuasive or even relevant rebuttal.
Carter's counter-argument has all the faults that he claims for Myers.
Edited by Wesley R. Elsberry on Sep. 15 2004,04:32
"You can't teach an old dogma new tricks." - Dorothy Parker