Illustrations of Ordovician, jawless vertebrates. Left is a Promissum conodont, ranging from 5 to 50 cm in length and named after unusual, cone-like teeth fossils, which are hypothesized to be ancestors of modern lampreys and hagfishes. On the right is a pair of Sacabambaspis, around 35 cm in length, which had distinct, forward-facing eyes and an armored head. Very few conodont species survived the Late Ordovician Extinction Event, and no fossils of animals like Sacabambaspis from after the event have been discovered.
© Nobu Tamura (CC BY-SA)
A recent paper published in Science Advances by Wahei Hagiwara and Professor Lauren Sallan of the Macroevolution Unit at the Okinawa Institute of Science and Technology, Japan, closes a long-standing gap in our understanding of the early radiation of vertebrates into jawed and jawless fishes following the Late Ordovician mass extinction, around ~445–443 million years ago. Their analysis shows that this radiation arose from a small number of fortunate survivors clinging on in ecological refugia. From those few lineages, of course, all modern marine and terrestrial vertebrates ultimately evolved.
This study neatly dismantles one of creationism’s favourite rhetorical fallbacks: the claim that Earth was deliberately “fine-tuned” to support complex life, and ultimately humans. The evolutionary pattern revealed here—near-annihilation followed by recovery from a few scattered refugia—is not the signature of foresight or optimisation, but of contingency and survival against the odds. Life does not flourish because conditions are perfectly arranged for it; rather, whatever happens to survive is forced to adapt to whatever conditions remain. The history of vertebrates, like that of life more generally, is therefore not one of careful planning, but of repeated catastrophe followed by opportunistic evolutionary radiation.
Creationists are notable for clinging to demonstrably false beliefs in the face of overwhelming evidence, childishly mistaking stubbornness for intellectual strength, rather like a spoilt toddler refusing to accept that they have just lost a game of Snap!. Alongside the patently absurd claim that Earth is only 6,000–10,000 years old sits the almost equally untenable belief that the planet was created exactly as it is, perfectly suited for human life. This notion is maintained despite abundant evidence for repeated mass extinctions driven by cosmic impacts, large-scale geological processes such as plate tectonics and associated seismic activity, major reorganisations of ocean circulation, and delicately balanced biogeochemical feedback systems involving oxygenation and carbon cycling that periodically spiral out of control, triggering catastrophic climate change.
What the evidence actually reveals is not a cosy, well-regulated world resembling some tranquil small town in Kansas, but a planet that is frequently so hostile to life that much of it is wiped out entirely. Most species go extinct, leaving only a handful of survivors to inherit the aftermath and radiate into new forms adapted to altered conditions—until they too are eliminated by some future catastrophe. The conclusion is unavoidable: Earth is not fine-tuned for human life, or for life in general. Instead, today’s species are the fortunate descendants of a few lucky survivors, shaped by natural selection to fit available ecological niches as neatly as a hand fits a glove.
Creationist Claim vs Reality.The two palaeontologists based their conclusions on an analysis of a comprehensive global database of fossil occurrences. How they carried out this work, and the evolutionary story it reveals, is explained in accessible terms in a research update from the Okinawa Institute of Science and Technology.Creationist claim:
Source: National Geographic
Earth was designed as a stable, life-friendly environment, finely tuned from the outset to support complex organisms and ultimately human beings.
Reality: Earth’s history is dominated by instability, violence, and repeated biological collapse.
Major mass extinctions and their impact
- Late Ordovician (~445–443 million years ago)
~85% of marine species lost. Early vertebrate diversity was devastated, with survival restricted to scattered ecological refugia.- Late Devonian (~372–359 million years ago)
~75% of species lost. Reef ecosystems collapsed repeatedly; early jawed fishes and marine invertebrates were severely reduced.- Permian–Triassic (“The Great Dying”, ~252 million years ago)
~90–96% of marine species and ~70% of terrestrial vertebrate species wiped out. Entire ecological structures were erased, requiring tens of millions of years to recover.- Triassic–Jurassic (~201 million years ago)
~80% of species lost. Cleared ecological space that allowed dinosaurs to dominate terrestrial ecosystems.- Cretaceous–Palaeogene (~66 million years ago)
~75% of species lost, including all non-avian dinosaurs. Mammals and birds radiated only because dominant competitors were eliminated.
Bottom line:
Life on Earth does not persist because conditions are carefully balanced or benevolently maintained. It survives because a few lineages repeatedly endure catastrophe by chance, then diversify into the ecological vacuum left behind. If Earth were truly “fine-tuned” for life, repeated near-sterilisation of the biosphere would not be a defining feature of its history.
Failure of Intelligent Design Predictions
Mass extinctions pose a fundamental problem for Intelligent Design and fine-tuning claims because they represent exactly what a designed biosphere should not exhibit. Design arguments routinely invoke optimisation, foresight, robustness, and stability; yet Earth’s history is marked instead by fragility, repeated collapse, and wholesale ecological failure. Entire, well-established ecosystems have been erased not once, but repeatedly, often by mechanisms external to biology itself—asteroid impacts, massive volcanism, runaway greenhouse effects, and ocean anoxia. Evolutionary theory predicts this pattern precisely: survival is contingent, not guaranteed, and long-term trends are shaped by bottlenecks, chance survival, and post-catastrophe radiation. Intelligent Design, by contrast, makes no coherent prediction that explains why a supposedly engineered world would repeatedly come within a hair’s breadth of biological annihilation.
Repeated mass extinctions repeatedly bottleneck life on Earth, with today’s biodiversity arising not from fine-tuning or design, but from the chance survival and subsequent radiation of a few fortunate lineages.
The Age of Fishes began with mass death
New fossil database gives unique insights into the earliest vertebrate ecosystems, revealing how mass extinction events are key drivers of evolutionary diversification.
445 million years ago, life on our planet was forever changed. During a geological blink of an eye, glaciers formed over the supercontinent Gondwana, drying out many of the vast, shallow seas like a sponge and giving us an ‘icehouse climate’ that, together with radically changed ocean chemistry, ultimately caused the extinction of about 85% of all marine species – the majority of life on Earth.
In a new Science Advances study, researchers from the Okinawa Institute of Science and Technology (OIST) have now proved that from this biological havoc, known as the Late Ordovician Mass Extinction (LOME), came an unprecedented richness of vertebrate life. During the upheaval, one group came to dominate all others, putting life on the path to what we know it as today: jawed vertebrates.
We have demonstrated that jawed fishes only became dominant because this event happened, and fundamentally, we have nuanced our understanding of evolution by drawing a line between the fossil record, ecology, and biogeography.
Professor Lauren Sallan, senior author
Macroevolution Unit
Okinawa Institute of Science and Technology
Onnason, Kunigamigun, Okinawa, Japan.
A fuller picture of life at the Ordovician sunset
The Ordovician period, spanning from roughly 486 to 443 million years ago, was a time when Earth looked very different. The southern supercontinent, Gondwana, dominated the planet, surrounded by vast, shallow seas. The poles were ice-free, and the water was pleasantly warm thanks to a greenhouse climate. And while the coasts were slowly being colonized by liverwort-like plants and many-legged arthropods, the surrounding basins were teeming with diverse – and bizarre – forms of life. Large-eyed, lamprey-like conodonts snaked around towering sea sponges, trilobites scuttled among swarms of shelled mollusks, while human-sized sea scorpions and giant nautiloids with pointy shells up to five meters in length patrolled the waters in search of prey. Few and far in between these strange creatures were the humble ancestors of gnathostomes, or jawed vertebrates, which would later come to dominate animal life on the planet.
While we don’t know the ultimate causes of LOME, we do know that there was a clear before and after the event. The fossil record shows it.
Professor Lauren Sallan.
The extinction came in two pulses: First, the planet rapidly switched from a greenhouse to an icehouse climate, covering most of Gondwana with glaciers that dried out the shallow ocean habitats. Then, a few million years later, just as biodiversity was beginning to recover, the climate flipped again, melting the icecaps and drowning the now cold-adapted marine life with warm, sulfuric, and oxygen-depleted water.
During and after these waves of death, most of the vertebrate survivors were confined to refugia – isolated biodiversity hotspots separated by unsurmountable swaths of deep ocean – where surviving gnathostomes evidently had an advantage.
We pulled together 200 years of late Ordovician and early Silurian paleontology creating a new database of the fossil record that helped us reconstruct the ecosystems of the refugia. From this, we could quantify the genus-level diversity of the period, showing how LOME led directly to a gradual, but dramatic increase in gnathostome biodiversity. And the trend is clear – the mass extinction pulses led directly to increased speciation after several millions of years.
Wahei Hagiwara, first author
Macroevolution Unit
Okinawa Institute of Science and Technology
Onnason, Kunigamigun, Okinawa, Japan.
The fall in jawless vertebrates coincides with the rise of jawed vertebrates following the two pulses of the Late Ordovician Mass Extinction (LOME). Top genus-level diversity curves follow global, taxonomic richness in genera – i.e. the number of identified genera - per geological stage (A.) and per million years in each stage (B.). Notice the sharp change during the final stage of the Ordovician period, the Hirnantian (Hir). C. shows genus-level richness per stage for 13 different gnathostomes groups. Note that while gnathostomes denote jawed vertebrates today, many jawless forms lived in the Ordovician and Silurian periods, as these split off from our ancestors before the origin of jaws. D. shows diversity curves across 5 major regions at the time, highlighting the impact of isolation to specific refugia.© Hagiwara & Sallan, 2025
From toothed “worms” to Darwin's finches
In constructing this comprehensive database of fossils from across the world, the researchers were able to link the rising gnathostome biodiversity to not only LOME, but also location.
This is the first time that we’ve been able to quantitatively examine the biogeography before and after a mass extinction event. We could trace the movement of species across the globe – and it’s how we’ve been able to identify specific refugia, which we now know played a significant role in the subsequent diversification of all vertebrates.
Professor Lauren Sallan.
For example, in what is now South China, we see the first full-body fossils of jawed fishes that are directly related to modern sharks. They were concentrated in these stable refugia for millions of years until they had evolved the ability to cross the open ocean to other ecosystems.
Wahei Hagiwara
By integrating the fossil record with biogeography, morphology, and ecology, these findings have helped nuance our understanding of evolution.
Did jaws evolve in order to create a new ecological niche, or did our ancestors fill an existing niche first, and then diversify? Our study points to the latter. In being confined to geographically small areas with lots of open slots in the ecosystem left by the dead jawless vertebrates and other animals, gnathostomes could suddenly inhabit a wide range of different niches.
Professor Lauren Sallan.
A similar trend is clear with Darwin’s finches on the Galápagos Islands, which took advantage of new opportunities to diversify their diet to survive – and over time, their beaks evolved different shapes to better suit the niche they came to occupy.
While the jawed fishes were trapped in South China, their jawless relatives continued to evolve in parallel elsewhere, ruling the wider seas for the next 40 million years. These diversified into many different forms of reef fishes, some of which had alternative mouth structures. But why jawed fishes, among all other survivors, came to dominate later once they spread from the refugia remains mysterious.
The researchers found that rather than wiping the slate clean, LOME triggered an ecological reset. Early vertebrates stepped into the niches left vacant by conodonts and arthropods, rebuilding the same ecological structure but with new species. This pattern repeats across the Paleozoic following extinction events driven by similar environmental conditions, forming what the team calls a recurring ‘diversity-reset cycle’ in which evolution restores ecosystems by converging on the same functional designs.By integrating location, morphology, ecology, and biodiversity, we can finally see how early vertebrate ecosystems rebuilt themselves after major environmental disruptions. This work helps explain why jaws evolved, why jawed vertebrates ultimately prevailed, and why modern marine life traces back to these survivors rather than to earlier forms like conodonts and trilobites. Revealing these long-term patterns and their underlying processes is one of the exciting aspects of evolutionary biology.
Professor Lauren Sallan.
Publication:
The findings of Hagiwara and Sallan add to an already overwhelming body of evidence that the history of life on Earth is one of repeated catastrophe, survival by chance, and evolutionary recovery—not careful planning or benevolent design. The radiation of vertebrates following the Late Ordovician mass extinction was not an orderly unfolding towards some predetermined goal, but the opportunistic expansion of a few lineages that happened to persist when most life was wiped out.
This pattern is exactly what evolutionary theory predicts and exactly what creationism and Intelligent Design cannot explain. A planet supposedly fine-tuned for life should not repeatedly come within a whisker of biological sterilisation, nor should its ecosystems require tens of millions of years to recover from self-inflicted “design features” such as runaway climate feedbacks and global ocean anoxia. That life persists at all is not evidence of foresight, but of the brutal efficiency of natural selection acting on whatever fragments remain.
In short, humans are not the intended outcome of a carefully engineered world. We are the contingent products of deep time, mass death, and improbable survival—descendants of a few lucky survivors, shaped by evolution to fit the niches left vacant by extinction. Far from undermining evolutionary theory, discoveries like this reinforce it, while pushing creationist claims ever further into the realm of denial rather than explanation.
If this leaves creationists not feeling important enough, then so be it. Reality has no obligation to comply with their requirements, no matter how important they imagine they are.
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