Posted: Apr 13, 2010 9:11 am
by Rumraket
rainbow wrote:
Rumraket wrote:If you claim those papers do not constitute evidence, you may aswell say that there is "no evidence for macroevolution" since, noone has ever seen a fish turn in to a mammal. Its false on the same level.

There is a great deal of fossil evidence to support Evolution.
There is EXACTLY ZERO fossil evidence to support Abiogenesis.
Therefore you are wrong.

You are setting an almost impossible standard. Whatever direct evidence of abiogenesis there was is surely lost now. I can't even begin to imagine the circumstances required to fossilize and preserve protocellular material for >3500 million years in the earth's ever changing crust.

Even if some kind of fossilised protocellular material exists in some obscure rocks somewhere, we might not even be able to identify them as that. How do you even get direct evidence for a chain of chemical events that old? It's not like there's going to be a fossilised schematic of the formose reaction laying around with a detailed summary of the circumstances wherein it happened.

Microoganisms don't fossilise that well(, they mostly leave behind some metal and mineral deposits in the shape of their "bodies", and may sometimes contain clues to membrane material.
Double fossilization in eukaryotic microorganisms from Lower Cretaceous amber
A major problem for understanding the origin of life, microbial evolution and phylogeny is the lack of microbial fossils. It is especially evident when we consider the available well-preserved record of pluricellular organisms, animals and plants [1]. Microfossils are not only useful for elucidating biological macro- and microevolution but also the biogeochemical history of our planet. Amber is a fossilized resin originating from the trunk and roots of certain trees, particularly of the genera Agathis and Hymenaea. It acts as a natural embedding agent and it has properties similar to amorphous polymeric glass [2]. Amber consists of a complex mixture of terpenoid and/or phenolic compounds. The organisms that are embedded in it
are maintained in their three-dimensional form and their morphological features are preserved, making it possible
to compare them with their present-day descendants [3].
Trapping in amber is not the most frequent mechanism of preservation of biological systems, especially of the socalled
soft-bodied fossils (for example, nematodes and insects); mineralization as a result of both microbial and abiotic processes is the most common mechanism. Two main mechanisms of fossilization by mineralization are recognized: permineralization, which is the result of early infiltration and permeation of cells and/or tissues by mineral-charged water; and replication of morphology in authigenic minerals which are mainly a product of bacterial activity [4]. Mineralization in pyrite is called pyritization.
Pyrite is the most common sulphide mineral found in marine argillaceous sedimentary rocks, where it can occur in a variety of crystallographic and textural forms [5]. Pyritization is considered an important mode of preservation and/or fossilization in animals and plants, with or without a skeleton or cuticle [6-8]. Although little detailed work has been published on pyrite in fossils, three grades of biological preservation by pyritization have been recognized [5,9]: 1) permineralization, involving
pyrite precipitation in cellular cavities or cell walls made of poorly biodegradable components such as cellulose and chitin; 2) formation of mineral coats, which is usually involved in the preservation of very degradable biological components. These pyrite coats have a limited and clearly defined thickness; and 3) formation of mineral casts or moulds. This style of preservation causes the greatest degree of biological information loss, since only the fossil outline is preserved. The main difference between these three modes of preservation by pyritization is the extent of mineral precipitation.

The oldest clues we have are the stromatolites at abot 3,5 billion years and these themselves don't contain any direct clues to the constituents of whatever life it may have been, since all there is left are conical shaped microstructures.
Warrawoona Group in Western Australia - a scientific dispute
The putative stromatolites with microstructures resembling bacteria from the extensive stromatolitic formations of the 3,430-million-year-old Strelley Pool Chert within the Warrawoona Group in Western Australia have been hotly debated ever since their discovery by Lowe (1980, 1983). Lowe (1994) later ascribed conical form genera to abiotic evaporative precipitation, as did Grotzinger (1999), and Brasier (2002) also found no support for the microfossils as biomarkers. Whether microstructures within the Warrawoona Group stromatolites are the imprints of ancient filamentous and possibly photosynthetic microbes as argued by Schopf (1987, 1993) and Awramik (1992) became a heated debate that remains unresolved. A recent and extensive study of seven distinct stromatolitic form genera by Allwood (2006) certainly lends support to proponents of biogenetic origins of the chert, since the simultaneous set of forms is more difficult to explain with known abiogenic processes. However, whether the microstructures are fossil microbes remains unresolved. If they are microbe fossils, there would still remain the critical question of what type they are, archaea, cyanobacteria, another type of photosynthetic bacteria, chemosynthetic bacteria, or some combination of these.

The most recent paper I could find on the subject actually found *some* organic material leftover, but it was more or less unidentifiable:
Controls on development and diversity of Early Archean stromatolites (2009)
The 3,450-million-year-old Strelley Pool Formation in Western
Australia contains a reef-like assembly of laminated sedimentary
accretion structures (stromatolites) that have macroscale characteristics
suggestive of biological influence. However, direct microscale
evidence of biology—namely, organic microbial remains
or biosedimentary fabrics—has to date eluded discovery in the
extensively-recrystallized rocks. Recently-identified outcrops with
relatively good textural preservation record microscale evidence of
primary sedimentary processes, including some that indicate probable
microbial mat formation. Furthermore, we find relict fabrics
and organic layers that covary with stromatolite morphology,
linking morphologic diversity to changes in sedimentation, seafloor
mineral precipitation, and inferred microbial mat development.
Thus, the most direct and compelling signatures of life in the
Strelley Pool Formation are those observed at the microscopic
scale. By examining spatiotemporal changes in microscale characteristics
it is possible not only to recognize the presence of
probable microbial mats during stromatolite development, but
also to infer aspects of the biological inputs to stromatolite
morphogenesis. The persistence of an inferred biological signal
through changing environmental circumstances and stromatolite
types indicates that benthic microbial populations adapted to
shifting environmental conditions in early oceans.


Genesis and Variability of Stromatolites
The existence of microbial mats during formation of stromatolites in the Strelley Pool Formation can be deduced from different sets of evidence in multiple stromatolite types. In domical stromatolites, evidence of microbial mat formation lies in the observation that cohesive layers of organic material formed at discrete, regular intervals at the surface of stromatolites, coupled with the fact that those laminae adhered to the steep stromatolite margins and did not preferentially thicken into topographic lows. In the coniform stromatolites,microbial activity is inferred from the juxtaposition of
contemporaneous but contrasting sedimentary fabrics and their arrangement within the context of stromatolite morphology. In both instances the interpretation benefits from comparisons with microbially-influenced microstructure in well-preserved Proterozoic stromatolites (25). Unfortunately, microfossils are not preserved because of redistribution of the organic material by neomorphic crystal growth during recrystallization. Biomarker preservation is possible but perhaps unlikely because of the thermal maturity of the organic matter (28).