Refuting Creationism - Interactions Between Earth’s Early Life Forms And The Environment - Over 500 million Years Before 'Creation Week'

AI-generated image of what the ocean may have looked like during the Paleozoic era, around 500 million years ago.

AI-generated image of ancient phytoplankton in oxygen rich seawater.

Scientists Untangle Interactions Between the Earth’s Early Life Forms and the Environment over 500 million Years - College of Arts & Sciences at Syracuse University

One of creationism's problems is that, by insisting the Universe is only 10,000 years old or less, they place 99.9975% of Earth's history in that very long, pre-Creation period when, according to their mythology, there wasn't any history.

This, of course, is trivially easy to refute simply by finding evidence of something that happened during this period, and since almost all of history did, this is not much of challenge.

As I've remarked before, creationism is not a problem for science; science is a problem for creationism - which is why creationists spend almost all their time attacking science and lying about it to get new recruits, while all science need do is produce a few facts now and then - something it does incidentally, without even thinking about creationism.

Describe life in Earth's oceans 500 million years ago. Life in Earth's oceans 500 million years ago, during the Cambrian Period, was incredibly diverse and vibrant, marking a significant point in evolutionary history known as the Cambrian Explosion. This era saw the rapid diversification of life forms, particularly marine organisms, resulting in the establishment of many major groups of animals that exist today.

Major Characteristics of Cambrian Marine Life:

1. Emergence of Complex Ecosystems:
   • Marine environments were teeming with a variety of life forms, including a wide range of invertebrates.
   • Ecosystems were complex, with different organisms occupying various ecological niches.
2. Biodiversity:
   • The Cambrian Explosion led to an unprecedented increase in biodiversity.
   • Many major animal phyla first appeared during this period, including arthropods, mollusks, echinoderms, and brachiopods.

Notable Marine Organisms:

1. Trilobites:
   • Trilobites were one of the most successful and diverse groups of arthropods.
   • They had segmented bodies and exoskeletons, which they molted as they grew.
2. Anomalocaris:
   • Anomalocaris was a large predator, considered one of the top predators of its time.
   • It had a segmented body, large eyes, and grasping appendages for capturing prey.
3. Opabinia:
   • Opabinia was a bizarre-looking creature with five eyes and a long, flexible proboscis with a claw at the end.
   • It likely used its proboscis to probe the seafloor for food.
4. Wiwaxia:
   • Wiwaxia had a soft, slug-like body covered in protective scales and spines.
   • It likely fed on detritus or small organisms on the ocean floor.
5. Hallucigenia:
   • Hallucigenia was a small, spiny creature with elongated, paired spines along its back.
   • Its feet were tentacle-like, possibly used for locomotion and feeding.
6. Brachiopods:
   • Brachiopods were bivalve-like organisms with hard shells and a distinctive feeding structure called a lophophore.
   • They were abundant and formed extensive communities on the seafloor.
7. Echinoderms:
   • Early echinoderms, the group that includes modern starfish and sea urchins, were also present.
   • They displayed a range of body forms and modes of life.

Marine Flora and Microorganisms:

• Algae:
  • Marine algae were the primary producers, forming the base of the food web.
  • Cyanobacteria and other photosynthetic microorganisms were crucial for oxygen production.
• Sponges and Cnidarians:
  • Early sponges filtered water to extract food particles.
  • Primitive cnidarians, including early jellyfish and corals, were also part of the marine communities.

Environmental Conditions:

• Oxygen Levels:
  • Oxygen levels in the oceans were lower than today but sufficient to support a wide range of aerobic organisms.
• Climate:
  • The climate was generally warmer, with no polar ice caps, leading to higher sea levels and extensive shallow marine habitats.

Evolutionary Significance:

• The Cambrian Period was crucial for the development of complex life forms.
• It laid the groundwork for future evolutionary innovations and the establishment of complex food webs.

In summary, 500 million years ago, Earth's oceans were a cradle of life, marked by extraordinary diversity and evolutionary innovation, setting the stage for the complex marine ecosystems we see today.

Sadly for creationism, that 'now and then' occurs multiple times a day with the publication of just about every evolutionary biology, geology, archaeology, palaeontology and cosmology paper - papers such as this one by an interdisciplinary team led by Professor Zunli Lu of Syracuse University, New York, USA:
Professor Lu's team have traced the interaction between the atmosphere, the oceans and life on Earth over the past 500 million years and shown how they co-evolved. The team have published their findings, open access, in the journal National Science Review and explain it in a Syracuse University press release by John H. Tibbetts:

Scientists Untangle Interactions Between the Earth’s Early Life Forms and the Environment over 500 million Years

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Syracuse University Thonis Family Professor Zunli Lu leads an interdisciplinary group exploring how biology and the physical environment co-evolved.

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The atmosphere, the ocean and life on Earth interacted over the past 500-plus million years in ways that improved conditions for early organisms to thrive. Now, an interdisciplinary team of scientists has produced a perspective article of this co-evolutionary history published in multidisciplinary open-access journal National Science Review (Oxford University Press, Impact Factor 20.7).

One of our tasks was to summarize the most important discoveries about carbon dioxide and oxygen in the atmosphere and ocean over the past 500 million years. We reviewed how those physical changes affected the evolution of life in the ocean. But it’s a two-way street. The evolution of life also impacted the chemical environment. It is not a trivial task to understand how to build a habitable Earth over long time scales.

Professor Zunli Lu, co-lead author
Department of Earth & Environmental Sciences
University of Syracuse, Syracuse, USA.

The team from Syracuse University, Oxford University and Stanford University explored the intricate feedbacks among ancient life forms, including plants and animals, and the chemical environment in the current Phanerozoic Eon, which began approximately 540 million years ago.

At the start of the Phanerozoic, carbon dioxide levels in the atmosphere were high, and oxygen levels were low. Such a condition would be difficult for many modern organisms to thrive. But ocean algae changed that. They absorbed carbon dioxide from the atmosphere, locked it into organic matter and produced oxygen through photosynthesis.

The ability of animals to live in an ocean environment was affected by oxygen levels. Lu is studying where and when ocean oxygen levels may have risen or fallen during the Phanerozoic using geochemical proxies and model simulations. Co-author Jonathan Payne, professor of Earth and planetary sciences at Stanford University, compares an ancient animal’s estimated metabolic requirements to places where it survived or disappeared in the fossil record.

As photosynthetic algae removed atmospheric carbon into sedimentary rocks to lower carbon dioxide and raise oxygen levels, the algae’s enzymes became less efficient in fixing carbon. Therefore, algae had to figure out more complicated ways of doing photosynthesis at lower carbon dioxide and higher oxygen levels. It accomplished this by creating internal compartments for photosynthesis with control over the chemistry.

For algae, it is changes in the environmental ratio of O₂/CO₂ that seems to be key to driving improved photosynthetic efficiency. What is really intriguing is that these improvements in photosynthetic efficiency may have expanded the chemical envelope of habitability for many forms of life.

Professor Rosalind Rickaby, co-lead author
Department of Earth Sciences,
University of Oxford, Oxford, UK

Ancient photosynthesizers had to adapt to changes in the physical environment that they themselves had created, notes Lu.

The first part of the history of the Phanerozoic is increasing habitability for life, and then the second part is adaptation.

Professor Zunli Lu.

If scientists want to further understand this interplay between life and the physical environment, as well as the drivers and limits on habitability, the authors suggest that mapping out the spatial patterns of ocean oxygen, biomarkers for photosynthesis and metabolic tolerance of animals shown in fossil records will be a key future research direction.

Unusually for a scientific paper, this one doesn't have an abstract, but it runs through the key stages involved in the co-evolution of life in the oceans and the atmosphere. It's an interesting account of how the environment shapes the organisms within it and how the organisms shape their environment in a co-evolutionary process that results in the environment looking as though it was designed for the life in it, which looks designed for the environment:

Atmospheric carbon dioxide and oxygen concentrations are partially linked via the geological cycle of organic carbon (Fig. 1A–C; e.g. CO₂ + H₂O ↔ CH₂O + O₂). The history of these two biologically active components, controls on their concentrations, and implications for the complexity of the biosphere and habitability of Earth have been hotly debated, but are generally considered independently. Ribulose bisphosphate carboxylase/oxygenase, Rubisco, is the enzyme responsible for all oxygenic photosynthesis, carbon fixation, and is the gatekeeper of energy flow to the animal kingdom. Since Rubisco also fixes O₂ as part of photorespiration, O₂ and CO₂ compete for the active site of Rubisco. Episodes of enhanced organic carbon burial contributed to removing carbon and releasing oxygen to the environment, particularly after the advent of land biota so dramatically increased the O₂:CO₂ ratio (Fig. 1B). This increase in O₂:CO₂ should have influenced the efficiency of Rubisco, shifting the balance towards the energy-sapping photorespiration and limiting the carbon fixation ability of plants and algae, thereby reducing new productivity and the energy cascade to the higher trophic levels within the ecosystem. However, the complexity of the modern ecosystem has emerged and thrived amidst this backdrop of increasing O₂:CO₂ throughout the Phanerozoic, which raises key research questions regarding evolution and habitability. To what extent can the biosphere adapt to variations caused by geological cycles? Are there Gaia-like feedbacks between life and their physical environment that assist in maintaining Earth's habitability? Does the biosphere itself limit the range of environmental possibilities?

(A) Schematic cartoon illustrating the main processes discussed in this paper. Ocean DO stands for ocean dissolved oxygen. (B) Modelled atmospheric pO₂ in blue [2]. Proxy-based pCO₂ estimates in brown solid line, 0–420 Ma [1] and modelled pCO₂, brown dash line, 420–500 Ma [24] (C) Burial rates of organic matter (black line), compared to the calculated ratio of dissolved O₂:CO₂ (blue line) in the ocean using the equations for equilibrium of dissolved CO₂ and O₂ concentrations of seawater constrained by temperature and salinity (Supplementary materials). (D) The average C28/C29-sterane ratio of algal biomarkers [10]. The number of genera of marine animals across the Phanerozoic [23]. (E) The range of seawater temperature (°C) and dissolved oxygen (DO) concentrations (atm) for ecological sustainably of a hypothetical ecophysiotype population (modified from [7]) where Φ is its metabolic index defined as the ratio of O₂ supply to an organism's resting O₂ demand. The critical metabolic index, Φ_crit, is the minimal requirement for survival.

Figure 1.(A) Schematic cartoon illustrating the main processes discussed in this paper. Ocean DO stands for ocean dissolved oxygen. (B) Modelled atmospheric pO₂ in blue [2]. Proxy-based pCO₂ estimates in brown solid line, 0–420 Ma [1] and modelled pCO₂, brown dash line, 420–500 Ma [24] (C) Burial rates of organic matter (black line), compared to the calculated ratio of dissolved O₂:CO₂ (blue line) in the ocean using the equations for equilibrium of dissolved CO₂ and O₂ concentrations of seawater constrained by temperature and salinity (Supplementary materials). (D) The average C28/C29-sterane ratio of algal biomarkers [10]. The number of genera of marine animals across the Phanerozoic [23]. (E) The range of seawater temperature (°C) and dissolved oxygen (DO) concentrations (atm) for ecological sustainably of a hypothetical ecophysiotype population (modified from [7]) where Φ is its metabolic index defined as the ratio of O₂ supply to an organism's resting O₂ demand. The critical metabolic index, Φ^crit, is the minimal requirement for survival.

Here we link the history of Phanerozoic O₂ and CO₂ concentrations and draw together the evolution of marine algal primary producers and the diversity history of marine animals to explore feedbacks between life and the environment. We emphasize that spatially resolved coupled redox and fossil evidence may be key to understanding feedbacks between the biosphere and the geosphere, as well as the drivers and limits on habitability.

MODEL AND PROXY RECONSTRUCTIONS FOR CO₂ AND O₂
Phanerozoic reconstructions of atmospheric pCO₂ have converged over the last decade (Fig. 1B). Proxy records, such as leaf stomata, pedogenic carbonate δ¹³C and boron isotopes, extend back to ∼420 Ma, showing pCO₂ peaking above 2000 ppm during two greenhouse episodes (Silurian and early Mesozoic) each followed by declines to near-modern levels associated with icehouse climates [1]. Atmospheric pO₂ curves derived from mass-balance models agree on low pO₂ (<∼0.5 PAL) from the Cambrian to early Silurian, in contrast to the rest of the Phanerozoic (1 PAL or higher) [2]. There is disagreement about when pO₂ reached the highest level (e.g. during the Carboniferous). pO₂ proxies broadly concur with the modelling [2], although the models based on isotopic mass balance (of δ¹³C and δ¹³C etc.) still have uncertainties. Establishing novel quantitative pO₂ proxies remains challenging. It is unclear whether the recent pO₂ proxy estimates are more reliable than the charcoal record, while charcoal production could be influenced by fuel availability for wildfires instead of pO₂. Overall, the first-order trend is that atmospheric pCO₂ decreased and pO₂ increased during the Phanerozoic, albeit with considerable temporal variations and uncertainty.

Climate conditions (reflected in pCO₂) did not dominate subsurface oceanic O₂ over the Phanerozoic on the time scale of a hundred million years ([3] and Supplementary materials). Extensive ocean anoxia has been identified in several intervals even under relatively high atmospheric pO₂ and sometimes associated with major mass extinctions (e.g. [4,5]), highlighting the decoupling between oceanic and atmospheric oxygen levels. Significant spatial heterogeneity in dissolved oxygen (DO) existed in global oceans throughout the Phanerozoic and there is no simple way of predicting temporal changes in the spatial DO pattern [3]. These findings highlight the need to map ocean DO spatially for distinct time slices, regardless of the challenges of DO proxies (Supplementary materials). Earth system models (like cGENIE) are a promising tool to reconcile multiple marine redox proxies with atmospheric composition [6], and produce quantitative global DO estimates critical for constraining extinction vulnerability [7]. A ‘deep-time paleoceanographic data-model comparison’ approach is likely the key to reconstructing Phanerozoic DO patterns, reconciling global and local redox proxy data, and for investigation alongside the evolving biosphere.

ALGAL EVOLUTION
The oceans experienced three distinctive algal eras, evidenced from three independent sources of microfossils, molecular biomarkers, and molecular clocks for individual clades (e.g. [8]). The ocean was first dominated by cyanobacteria until the end of the Sturtian glaciation, followed by the rise of green algae (Chlorophyta, primary endosymbionts). In the Devonian, there was an expansion of more derived prasinophyte algae (Chlorophyta) [8] before a second major phytoplankton succession took place at the transition from the Palaeozoic to the Mesozoic. At this time, the ocean, dominated by the green Archaeplastida, transformed into one dominated by secondary endosymbiotic algae with red algal-derived plastids, including the haptophytes (e.g. coccolithophores) and heterokont (e.g. diatom) lineages [8–10].

This Phanerozoic algal succession represents selection for more highly discriminant Rubiscos coupled with enhanced obligate aerobic metabolisms [11]. Rising marine O₂:CO₂ ratios (Fig. 1C) may have been among the drivers for these different phases of algal domination [10]. The final transition to the secondary endosymbiont bearing red algae lineage may have coincided with a decrease in surface ocean O₂:CO₂ (Fig. 1D), but notably a change in the spatial structure of oxygen within the ocean would result in an increased upper ocean oxygen content due to the persistent deepening of the oxygen minimum zones [12].

The compensation points of O₂ and CO₂ (Supplementary materials), controlled by the efficiency of photosynthetic pathways, have been proposed to impose absolute limits on atmospheric composition and set the O₂:CO₂ of the modern atmosphere [13], although the O₂-dependency of fire risk may outweigh these biochemical limits. During the Phanerozoic, the terrestrial flora had consistently been dominated by C3 photosynthesis with a Rubisco specificity (\(\tau\)) of likely ∼80. \(\tau\) is a unitless measure of the relative affinity and rate of turnover for CO₂ over O₂, calculated as \(\tau\) = (k_cat,C/K_C)/(k_cat,O/K_O). In the marine realm, the poorly discriminating Precambrian cyanobacterial Rubisco \(\tau\) ∼ 40–50) were surpassed by the intermediate Rubisco of the Chlorophyta (\(\tau\) ∼ 60–80) from the Sturtian deglaciation through the Palaeozoic, before the final transition at the Mesozoic to the most highly selective Rubisco of the chlorophyll a + c containing algae (\(\tau\) ∼ 80–120). O₂:CO₂ ratios rose to 5 at ∼400 Ma and then accelerated upwards to persistently high values of 25–40. These inefficient cyanobacteria and green algal Rubiscos would have been pushed close to their carbon compensation point yielding low net carbon fixation rates. Such conditions could have limited the carbon fixation rates for the ecosystem, but promoted the initiation of carbon concentrating mechanisms (e.g. [14]) and enhanced the selective pressure for a more discriminating Rubisco of the red algal lineage. Indeed the emergence of the pyrenoid, an intrachloroplast compartment thought to be adapted to concentrate carbon around Rubisco, in the haptophytes at ∼350 Ma [10] (with positive selection in Rubisco), and in land hornworts ∼100 Ma and <35 Ma [15] all coincide with the highest values of our inferred O₂:CO₂ ratio.

Any increase in Rubisco specificity and/or the induction of CO₂ concentrating mechanisms to elevate chloroplast O₂:CO₂ lowers the CO₂ compensation point and elevates the O₂ compensation point. Over the Phanerozoic, Rubisco specificity improved by ∼3 fold and the induction of carbon concentrating mechanisms which elevated the internal CO₂ concentration at the active site of Rubisco, likely enhanced carbon fixation by ∼6–10 fold [16]. As a result of cells harnessing energy to create ancient high CO₂, low O₂ conditions at the active site of Rubisco, the CO₂ compensation point decreased towards the modern, driving a lower habitable CO₂ concentration. By contrast, even though the O₂ compensation point is proportional to CO₂ (which has declined ∼10–20 fold) and was therefore thought to be higher in the past [13], the direct dependence on the Rubisco specificity/carbon fixation efficiency means that the top threshold of habitable O₂ content of the atmosphere has most likely increased towards its highest value in the modern. The progressive steps of enhanced carbon concentrating efficiency through the Phanerozoic, have permitted higher atmospheric O₂ and aerobic capacity in the animal kingdom.

ANIMAL EVOLUTION
Oxygen availability has long been hypothesized as an important control on animal evolution due to its critical role in animal respiration and biosynthesis. More recently, the interaction between oxygen and temperature has been identified as a likely constraint on animal evolution. Metabolic demand in ectothermic animals (to a first approximation, everything that is not a mammal or a bird) increases exponentially with temperature. Consequently, ocean habitability must be considered in terms of the ratio of oxygen supply to oxygen demand (e.g. [7]). An implication of this physiological constraint is that animal tolerance to temperature variation and, especially, to higher temperatures is more limited at lower oxygen concentrations (Fig. 1E). Furthermore, temperature-dependent oxygen deficiency (not holding sufficient oxygen to meet animal metabolic demands) may occur in warm oceans before reaching the hypoxic or anoxic conditions recorded by geochemical proxies [17]. The coupled constraints of low oxygen and warm climate may have limited the earliest animals to deep, cold, thermally stable environments. Some of the earliest motile animals may have burrowed through photosynthetic microbial mats where oxygen produced by local photosynthesis was concentrated [18]. Limited oxygen availability may also have delayed the evolution of predators into the Cambrian due to their greater oxygen demand during prey capture and digestion [19]. Oxygen availability, combined with changes in climate, may also have modulated animal extinction in the oceans across time [20]. The general decline in extinction rates for marine animals across the Palaeozoic (540–252 Mya) has been hypothesized to result from an increase in oxygen availability, providing animals with greater physiological tolerance to changes in climate and greater ability to inhabit productive, shallow-marine environments that can support greater abundance and taxonomic diversity [7] and would have been further supported by overall cooling through this interval. In the Mesozoic, after atmospheric pO₂ had reached or exceeded present atmospheric levels, oceanic anoxic events, often associated with rapid climate warming pulses, coincided with some mass extinction events (e.g. [4]). Explicit modelling of physiological response to climate warming shows that temperature-dependent hypoxia can explain the spatial gradient in the end-Permian mass extinction [21] and may be useful in predicting the pattern and extent of extinction in the oceans during the next few centuries. Nonetheless, there is less evidence that the ratio of O₂ to CO₂ plays the kind of direct and important role in animal physiology and evolution that it does for algae and plants (Supplementary materials), although the haemoglobin and haemocyanin binding affinity for O₂ is diminished under elevated CO₂ conditions (the Bohr effect).

CO-EVOLUTION OF THE PHYSICAL ENVIRONMENT AND BIOSPHERE
The general cooling of our planet via a first-order decline of pCO₂ and the contrasting rise of the oxygen content accompanied two phases in the changing habitability for photosynthetic algae and animals: (1) the initial increase in marine habitability and (2) the subsequent biological adaptation/innovation as the atmospheric composition started to impinge on the opposite end of their physiological comfort zone (Fig. 1D). The evolution and advancement of the carbon concentrating mechanism might have been an essential step in the atmospheric engineering of the photosynthesizers to enable ever diminishing pCO₂ whilst allowing atmospheric pO₂ to further increase, maintaining a cooler and more oxygen-rich environment for the animals. Animals with closed circulatory systems, air-breathing (better access to O₂), greater levels of activity, and more control of body temperature are increasingly diverse and successful, becoming more independent of external conditions over time [22]. Both phytoplankton and animals are operating further from their natural limits over time, using energy to control the chemistry of their cellular environments to decouple their metabolisms from the environment, even if the environment itself would be less favourable had the organisms not evolved.

Associated with each algal transition is an increase in cell sizes of the phytoplankton, allowing greater compartmentalization and internal control, the addition of mineralizing skeletons which propagated intermediate-depth oxygenation [12] and accelerated the transfer of primary productivity towards larger-size organisms and higher trophic levels [9]. These transitions in the dominant groups of phytoplankton, each of which may have expanded the effective base of the food chain relative to the last, may help explain the long-term increases in the taxonomic diversity and ecological complexity (e.g. [23]). Such increases in animal size, motility, and levels of bioturbation may have recycled nutrients for marine photosynthesizers more efficiently and thus further stabilized biogeochemical cycles (Fig. 1A).

Future breakthroughs in understanding the co-evolution of atmospheric composition and Earth habitability may emerge from the ‘triple-junction’ of spatially resolved records of (1) ocean oxygen concentrations, (2) algal photosynthesis and associated biomarker evidence, and (3) quantitative estimates of animal metabolic tolerance and their corresponding fossil records.

Fundamental to this process has been the evolutionary improvement in the efficiency of Rubisco, one if the least efficient enzymes in all of nature. Rubisco is fundamental to the process of photosynthesis, so the more efficiently it fixes carbon from CO₂ the more O₂ it produces and the greater the O₂/CO₂ ratio in the atmosphere. The higher the ratio the higher is the partial pressure of O₂ (pCO₂) and the more readily it dissolves in sea water where it can be used for respiration by animal life. In addition to the pCO₂, solubility of O₂ in sea water is affected by sea temperature since O₂ is more readily soluble in cold water than in warm. A rise in CO₂ causes an increases in sea water temperature, so there have also been periods of anoxia, causing mass extinctions., such as the 'Ocean Anoxia Events' of 375-360 million years ago, 252 million years ago, and during the Jurassic and Cretaceous periods, when volcanic activity was responsible for a rise in CO₂.

The history of life in the oceans over the last 500 million years has been the history of a dynamic relationship between the evolution of algae and improved photosynthesis, the atmospheric O₂ that process produces, the greater the O₂/CO₂ ratio and the evolution of aerobic animal life. As the Theory of Evolution predicts, far from being perfectly tuned for life, life on Earth has had to continually adapt to an increasingly hostile environment and, as it has done so, it has contributed to changes in that environment. There has never been a period when living organisms and their environment have been in perfect harmony with neither needing to change and life and its environment being perfectly in tune.

History debunks the childish creationist notion of Earth being fine-tuned for life on it. Life is fine tuned for its environment by a process of evolution.

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