Refuting Evolution - Allopatric Evolution, Just as The Theory of Evolution Predicts

(a) Chamaecyparis obtusa in Japan

(b) C. obtusa var. formosana in Taiwan

Map of the South China Sea showing the Ryuku Arc between Taiwan and Kyushu

Google Maps

Natural Japanese and Taiwanese Hinoki Cypresses Genetically Differentiated 1 Million Years Ago | Research News - University of Tsukuba

Japanese plant geneticists, led by scientists from University of Tsukuba, have shown that the Japanese and Taiwanese Hinoki cypresses began to diverge around one million years ago, following the destruction of a land bridge that once connected Taiwan to the Japanese archipelago.

This is a textbook example of allopatric speciation, in which an isolated population diverges from its parent population through a combination of founder effects, genetic drift, and natural selection in response to different environmental pressures.

The now-vanished land bridge once linked Taiwan to the southern Japanese island of Kyushu. Its remnants form the Ryukyu Arc — a chain of small islands marking the south-eastern boundary of the South China Sea.

Faced with such clear evidence of speciation, creationists typically resort to a familiar tactic: redefining evolution into a straw man. They insist that “evolution” means one species turning in a single event into something utterly unrelated — for instance, that these cypresses should transform into daisies, cabbages, mammals, or birds. If such an absurd event ever occurred, it would in fact falsify evolutionary theory and throw the entire fields of biology and taxonomy into chaos. This is the standard creationist tactic on social media: misrepresent science, then demand that science defend the misrepresentation, and claim victory when it doesn’t.

The reality remains, however, that the divergence of these related species of cypress — and the fact that this divergence can be correlated precisely with geological change — stands as powerful evidence for Darwinian evolution. Charles Darwin knew nothing of genes, alleles, or genetic drift, yet his description of descent with modification through inherited traits is elegantly confirmed here by modern genetics and biogeography. The genus Chamaecyparis — commonly known as the false cypresses — is an evolutionarily interesting group of conifers in the cypress family Cupressaceae. Their distribution and divergence provide a good illustration of how geological change, climate oscillations, and geographic isolation have shaped the evolution of temperate conifers.

Creationism In Crisis - How Fungi Created The Conditions For Land Plants - A Billion Years Before 'Creation Week'

Top L. Chicken of the woods (Laetiporus sulphureus)

Top R. Sulphur tufts (Hypholoma fasciculare)

Bottom L. Common mould (Penicillium)

Bottom R. Mucor (microscopic view)

Fungi set the stage for life on land hundreds of millions of years earlier than thought | Okinawa Institute of Science and Technology OIST

In that vast expanse of pre-‘Creation Week’ history, when 99.9975% of Earth’s story had already unfolded, a pivotal event occurred that would set the planet on a path towards the astonishing diversity of life we see today. According to researchers led by scientists at the Okinawa Institute of Science and Technology, Japan, that turning point was the evolution of multicellular fungi.

Unlike animals and plants, in which multicellularity appears to have arisen only once, fungi seem to have achieved it independently on at least five separate occasions, between 1.4 and 0.9 billion years ago.

This innovation allowed fungi to colonise land and begin transforming bare rock and rock debris into soil. That process, in turn, created the conditions that later enabled plants to establish themselves on land.

In addition to shedding light on how multicellularity evolved in fungi — a process that involved horizontal gene transfer — this research significantly extends the known timeline of fungal evolution, pushing it back by hundreds of millions of years.

Of course, the authors of Genesis, unaware of the distinction between plants and fungi and apparently thinking all plants were angiosperms, made no mention of fungi at all. Their myth betrays no understanding that plants are living organisms or that green plants depend on sunlight for photosynthesis, since it describes them as being created the day before the sun (Genesis 1:15-17). It names only angiosperms while ignoring ferns, mosses, and algae (Genesis 1:11-12), and later claims that “every living substance” outside the Ark was destroyed (Genesis 7:4), as though plants, like rocks, would somehow have survived unscathed, to provide food for the animals afterwards, despite no mention of their preservation during the flood genocide.

Science, as ever, tells a very different story — one based not on gap-filling tales but on evidence written in fungal DNA and preserved in the fossil record. It is a story of awe and wonder, not at the supposed magical powers of an imagined creator, but at the relentless processes of evolution: variation, natural selection, and the exploitation of opportunity, producing the extraordinary biodiversity we see today.

Refuting Creationism - How Rodent Thumbnails Allowed Them to Be So Successful.

Thumbnail of the kangaroo rat.

Rafaela V. Missagia et al. (2025)

Most rodents have thumbnails instead of claws. It might help explain how they took over the world. | EurekAlert!

The discovery that ancient rodents evolved a thumbnail in place of a claw helps explain why they are the most successful mammalian order on the planet. That small anatomical change opened up a whole new range of ecological niches, triggering an explosive radiation of new rodent species.

This fact alone should worry creationists who cling to a child-like understanding of science. Their favourite avoidance tactic—when pressed for an example of evolution—is to retreat hastily down their rabbit hole with the familiar cry: “Ah! But that’s not real, ‘macro’-evolution. That’s just variation within a ‘kind’.”

Of course, creationists are consistently reticent about defining what they mean by “macro-evolution,” or explaining how the processes that supposedly produce it differ from those of normal evolution. In scientific terms, evolution is simply a change in allele frequencies in a population over time. There is no separate mechanism for “macro” versus “micro.”

So here’s the awkward question for them: was the evolution of the thumbnail from a claw a case of “macro-evolution” or not?

According to the new research, led by Rafaela Missagi of the University of São Paulo, Brazil, with collaborators from the Field Museum of Natural History (Chicago, USA), Northwestern University (Chicago, USA), and the Natural History Museum (London, UK), this change was pivotal. It allowed rodents to diversify into countless species—just as the elongation of bat fingers into wings enabled bats to radiate into hundreds of species. Crucially, in both cases no “new structures” were created from nothing; existing ones were repurposed.

This sort of question usually sends creationists scurrying for cover, chanting Bible verses as they go.

Unlike creationist dogma, which collapses under this kind of scrutiny, the new findings provide yet another vindication of evolutionary theory. Evolution predicts that when a new function arises, it can open up new ecological opportunities, leading to rapid diversification. Not because there is a plan, but because natural selection now has something new to work on.

Refuting Creationism - Evolutionary Divergence and Hybridization in Mediterranean Shearwaters

Critically endangered Balearic shearwater,
Puffinus mauritanicus

Credit: Kirk Zufelt

The Balearic shearwater (Puffinus mauretanicus, above) and the Mediterranean shearwater (Puffinus yelkouan, below) are two shearwater taxa that are genetically similar despite displaying morphological and migratory differences. The new study shows that these two taxa have undergone recurrent episodes of divergence and hybridization during the Pleistocene glacial and interglacial cycles, respectively. This serves as a key example of how hybridization can help preserve genetic diversity and evolutionary potential in threatened taxa.

Credit: Victor Paris

Hybridization between species has been crucial to the survival of Europe’s most threatened seabird - Current events - University of Barcelona

Like the story of human evolution, that of two seabirds in the shearwater family living in the Mediterranean shows a history of divergence, followed by episodes of hybridization and genetic remixing. Normally, from a conservation perspective, hybridization is considered a problem because it can erode the distinctiveness of threatened species, diluting unique traits.

However, in the case of the Mediterranean shearwater (Puffinus yelkouan) and the critically endangered Balearic shearwater (Puffinus mauretanicus), hybridization has had the opposite effect. By introducing genetic diversity into the Balearic shearwater, it may have improved the species’ chances of survival, potentially making the difference between persistence and extinction.

This evolutionary story sits uneasily with the worldview of Bible-literalist creationists. The very fact of species interbreeding undermines the notion of fixed, separately created “kinds.” It also contradicts the idea that a few thousand years ago all life was destroyed in a global flood, followed by a period of hyper-rapid diversification into the species we see today—a process which, according to creationist claims, left no trace in the fossil record. If hybridization had occurred during that supposed burst of post-Flood diversification, it would simply have blurred the lines between “kinds,” creating variation within species rather than producing the multitude of distinct species we observe today. In other words, the evidence shows that life’s history is one of gradual divergence, occasional genetic exchange, and long-term adaptation—not sudden, discrete acts of “special creation.”

A recent study led by Professors Julio Rozas, Marta Riutort, and Jacob González-Solís of the Faculty of Biology and the Biodiversity Research Institute of the University of Barcelona (IRBio), together with Joan Ferrer Obiol of the University of Milan, has revealed how this evolutionary pattern unfolded. Using genomic analysis, they showed that the two shearwater species have gone through repeated cycles of divergence and hybridization, largely driven by the glacial–interglacial rhythms of the Pleistocene. Each cycle of isolation and secondary contact left genetic signatures that are still visible today.

The researchers found a clear gradient of genetic differentiation across the Mediterranean, with hybrid populations becoming increasingly common as one moves westwards, culminating in the Balearic Islands of Ibiza and Formentera. Intriguingly, the shearwater population on Menorca is genetically closer to P. yelkouan than to P. mauretanicus, reflecting its history of admixture. Far from being detrimental, this interbreeding has enriched the Balearic shearwater’s genome, reducing inbreeding risks and helping to preserve adaptive traits that may otherwise have been lost.

Creationism Refuted - Rappid Diversification Linked To Rapid Environmental Changes

Most known species evolved during 'explosions' of diversity, shows first analysis across 'tree of life'

The Tree of Life

Gustav Klimt, 1909

A new study in Frontiers in Ecology & Evolution delivers a striking confirmation of evolutionary theory while dealing another blow to creationist claims. Researchers John J. Wiens (University of Arizona) and Daniel S. Moen (University of California, Riverside) show that the vast majority of Earth’s species richness stems from a handful of lineages that underwent explosive bursts of diversification — precisely what evolutionary theory predicts.

Analysing enormous datasets covering more than 2 million described species across multiple taxonomic levels, the team found that "over 80% of all known biodiversity is packed into the clades with the fastest diversification rates". This pattern holds true for animals, plants, insects, vertebrates, and even across kingdoms, showing that biodiversity is not spread evenly but arises overwhelmingly from rapid radiations and occurs at all taxonomic levels. The message is clear: most of life’s diversity comes from bursts of speciation linked to ecological opportunity and innovation, not from slow, uniform accumulation over time. The results reveal a universal pattern across the tree of life, confirming that natural selection acting on changing environments and new niches drives the extraordinary richness we see today. For creationists, this is more bad news. Their model of static “kinds” appearing fully formed cannot explain why biodiversity clusters so strongly in rapidly radiating groups, or why it forms the nested hierarchies that evolution predicts. The evidence instead shows life as a continuous, dynamic process of descent with modification from common ancestors—exactly as Darwin envisaged, and the exact opposite of “special creation.”

Refuting Creationism - Oldest-Known Evolutionary Arms Race in the Cambrian

Lapworthella fasciculata shells (under scanning electron microscope) from the Mernmerna Formation, Flinders Ranges, South Australia

R. Bicknell, et al (2025)

Oldest-Known Evolutionary “Arms Race” in the Cambrian | AMNH

Examples of Lapworthella fasciculata shells (under scanning electron microscope) from the Mernmerna Formation, Flinders Ranges, South Australia showing holes made by a perforating predator. Scale bars represent 200 micrometers.

R. Bicknell, et al (2025)

Perhaps Creationism's designer god is just a slow learner.

Anyone with an intellect greater than that of a plank should be capable of understanding the utter futility and waste in an arms race in which the strategy is to keep running faster just to stay in the same place. Arms races only make sense as the result of a game plan in which you can't communicate with your opponent and have no way of telling what he or she is thinking and if they gain the upper-hand, you lose. The only safe choice is to up the stakes - and that goes for your opponent too.

It becomes even more incomprehensible if the person you're having the arms race with is yourself, unless you're an amnesic with multiple personality disorder, and yet, if we believe creationists, that's exactly what their putative designer god is doing constantly.

Everywhere we look in nature, organisms are competing with one another for resources, or because one is trying to exploit the other as a food source in a predator-prey relationship or as a parasite trying to live in or on another organism and even killing it or making it weak and sickly as a byproduct of its parasitism. And yet creationists insist there is only one designer designing both sides in these arms races.

For some unfathomable reason, creationists like to imagine the idea of a celestial idiot having arms races with itself in millions of relationships in nature is a much better explanation than these arms races being the inevitable result of mindless evolutionary processes where a slight improvement increases the chances of leaving descendants while reducing the chance of the opponent doing the same, so creating a selection pressure for the next twist in the spiral.

Refuting Creationism - Another Gap Closed - No God Found

A mating pair of wild-type (left) and mir-193 mutant (right) Bicyclus anynana butterflies.

Photo credit: Shen TIAN

A mating pair of peppered moths, Biston betularia, showing the melanistic and pale forms.

A microRNA solves an evolutionary mystery of butterfly and moth wing colouration - NUS Faculty of Science | NUS Faculty of Science

A regularly-cited example of observed Darwinian evolution is that of the peppered moth which occurs in two forms, the white, speckled form and a melanistic, almost black form. During the industrial revolution, as English northern towns grew and became polluted by smoke from coal-burning factories, so the melanistic form became more common.

Experiments showed that the lighter form became easier for predators to see when the moths were roosting on tree trunks that had become coated in soot, while the melanistic form became harder for predators to see.

Following the decline of the northern towns, the light form again increased back to the former ratio, showing the importance of environmental change in evolution.

This tendency to have melanistic forms is common in the lepidoptera (moths and butterflies) and this tendency was believed to be under th control of as single genomic region surrounding the protein-coding gene “cortex“, common across many species, showing their descent from a common ancestor.

However, new research by international researchers from Singapore, Japan, and the United States of America, led by Professor Antónia MONTEIRO and Dr Shen TIAN from the Department of Biological Sciences at the National University of Singapore (NUS), has shown that 'cortex' is not directly involved in producing melanism, instead, this is controlled by a microRNA from within the 'cortex' genomic region, as another example of how microRNA's control many functions within cells, particular gene expression.

Refuting Creationism - How Daisies Speciated On Isolated Islands

Top: Pleurophyllum speciosum
Bottom: Pulicaria canariensis

Top: Bidens mooreensis
Bottom: Argyroxiphium sandwicense

Pleurophyllum speciosum - Campbell Island.

Credit Phil Garnock-Jones.

Isolated daisies have the greatest diversity | Naturalis

Creationists try to get round the absurdity of the Bible myth which has two (or seven) of every species being packed into a wooden boat small enough to survive turbulent seas for a year, by introducing a new element to the myth that their god forgot to include - that there were just two (or seven) of each 'kind' and all of them underwent a period of warp-speed evolution (that non-one seemed to have noted) with several new species popping into existence each generation to give the many millions of known terrestrial species we have today.

Understandably, creationists are reticent to put any numbers on their claim. They won't say how many different 'kinds' there were on the boat, how many new species arose at each generation and for how long this period of fantastical speciation lasted. Nor will they define 'kind' in any meaningful way that matches any recognisable taxon. I have even been told it can mean 'animal kind' and 'plant kind'. It seems to vary according to the needs of the argument.

And they won't say why some 'kinds' have just one or two species while others have hundreds, or in the case of the Asteraceae family of plants, some 34,000 distinct species, so some must have been speciating much faster then other while some hardly bothered if at all.

In the later case, we now have a substantial database compiled by a team at the Naturalis Biodiversity Center, Leiden, The Netherlands which catalogues all 34,000 different species with their geographical distribution, showing how they radiated and diversified into new species, colonising isolated islands and, like Darwin's finches, radiating into different species on each island in an archipelago.

Refuting Creationism - Arctic Sled Dogs Had Already Diversified Into Two Types At Least 1,700 Years Before 'Creation Week'

A predicted phenotypic reconstruction of the ancient Zhokhov sled dog

Smith, T.A; Srikanth, K; Huson, H.J. (2024)

A team of Siberian huskies races in the Anchorage Fur Rendezvous in 2013 in Alaska.

Britt Coon

Genomics reveals sled dogs’ Siberian lineage | Cornell Chronicle

The History of dogs and their co-evolution with humans as they diverged from their wolf ancestors is a fascinating and complex story, most of which, like 99.9975% of all of the history of life on Earth occurred before creationist's legendary 'Creation Week'.

'Creation Week' is when creationists believe a magic god made of nothing magicked a small universe consisting of a single flat planet with a dome over it, centred on the Middle East, all out of nothing, in just 6 days about 10,000 years ago, (although why an omnipotent god couldn't have done it all in an instant and needed 6 full days, with a day to recover from the effort, is never explained).

Refuting Creationism - Earliest Ancestors of the Tasmanian Tiger Were Alive 23-25 Million Years Before 'Creation Week'

Artist’s reconstruction of Badjcinus timfaulkneri scavenging on the carcass of Silvabestius michaelbirti, a wombat-like marsupial also from Hiatus Site.

Illustration by
Peter Schouten.

Tasmanian tiger, Thylacinus cynocephalus

AI generated image.

Earliest known ancestors of the extinct Tasmanian Tiger discovered – and some could even eat the bones and teeth of their prey - Taylor & Francis Newsroom

88 years ago today, the last Tasmanian tiger died in Beaumaris Zoo, Hobart, Tasmania.

It was the last in a line of carnivorous marsupial going back at least 23-25 million years ago, in the extended period of Earth's pre-'Creation Week' history when creationists believe there was nothing out of which a magic man made of nothing made everything in 6 days, just 10,000 years ago. According to creationist mythology, the Tasmanian tiger would have had no ancestors, being magically made from dirt just like every other living species.

This makes it hard for creation to explain the evidence of all those fossils known to be far older than 10,000 years and showing evidence of the evolution of extant species from ancient ancestors as species diversified from a single common ancestor which lived hundreds of millions of years ago, but then facts were never a problem for counter-factual creationism.

What information do you have on the extinct Tasmanian tiger? The Tasmanian tiger, also known as the thylacine (Thylacinus cynocephalus), was a carnivorous marsupial native to Tasmania, mainland Australia, and New Guinea. The thylacine looked somewhat like a medium-to-large dog with a slender body, a head resembling that of a wolf or dog, and distinctive dark stripes across its back and tail, giving it the nickname "Tasmanian tiger." However, it was more closely related to kangaroos and other marsupials.

Key Information about the Tasmanian Tiger:

1. Physical Description:
   • The thylacine was about the size of a large dog, with a length of up to 1.8 to 2 meters (including the tail) and a height at the shoulder of about 60 cm.
   • Its fur was short and coarse, typically tan or yellow-brown, with 13 to 20 dark stripes across its back and tail.
   • It had a long, stiff tail, similar to a kangaroo's, and could open its jaws incredibly wide, up to 120 degrees.
   
   
2. Habitat and Behavior:
   • The thylacine was a nocturnal and solitary animal, hunting at night and resting during the day in a den or hollow log.
   • It primarily fed on small to medium-sized animals, such as kangaroos, birds, and small mammals. Its diet may have also included carrion.
   
   
3. Extinction:
   • The thylacine was driven to extinction on the Australian mainland thousands of years ago, likely due to competition with humans and the dingo, a wild dog introduced to Australia.
   • In Tasmania, the species persisted until the 20th century. The last known wild thylacine was killed in 1930, and the last known individual in captivity died in 1936 at the Hobart Zoo in Tasmania.
   • Its extinction was primarily due to human activities, including hunting (encouraged by a bounty system), habitat destruction, and the introduction of diseases.
   
   
4. Conservation Efforts and "Rediscovery" Claims:
   • Despite being declared extinct, there have been numerous unconfirmed sightings and efforts to find surviving thylacines, but none have been scientifically verified.
   • Some scientific projects have explored the possibility of "de-extinction" using preserved DNA from museum specimens, but these efforts remain largely theoretical.
   
   
5. Cultural Significance:
   • The thylacine holds a unique place in Tasmanian culture and Australian folklore, often seen as a symbol of the tragedy of extinction and the need for wildlife conservation.
   • It appears on Tasmania's coat of arms and has been the subject of various books, documentaries, and studies.

Would you like to know more about any specific aspect of the Tasmanian tiger?

How the oldest ancestors of the Tasmanian tiger were discovered by palaeontologists from the University of New South Wales, Australia, is the subject of a Taylor & Francis news release:

Earliest known ancestors of the extinct Tasmanian Tiger discovered – and some could even eat the bones and teeth of their prey

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A marsupial which had an “extremely thick” jawbone, enabling it to consume even the bones and teeth of its prey is among a discovery of three, new ancient species of the modern Thylacines – otherwise known as the Tasmanian tiger, which went extinct 88 years ago.

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These new species each roamed Australia around 23-to-25 million years ago, during the late Oligocene, making them the “undoubted oldest members of this family ever discovered”.

Today – Australia’s National Threatened Species Day, which marks the death of the last Tasmanian Tiger in Hobart’s Beaumaris Zoo on the 7th of September 1936 – scientists from the University of New South Wales (UNSW) Vertebrate Palaeontology Lab publish their findings in the Journal of Vertebrate Paleontology.

The once suggested idea that Australia was dominated by reptilian carnivores during these 25 million-year-long intervals is steadily being dismantled as the fossil record of marsupial carnivores, such as these new thylacinids, increases with each new discovery. The diversity of mammalian carnivores at Riversleigh during this period rivals that seen in any other ecosystem, including the great mammalian carnivore radiation that developed in South America.

Timothy Churchill, lead author
University of New South Wales
Sydney, New South Wales, Australia.

The three new species were each found in the fossil-rich deposits in Riversleigh World Heritage Area.

The largest of these new species, Badjcinus timfaulkneri, weighed somewhere between 7-11 kilograms, about the same size as a large Tasmanian Devil. Alike the Tasmanian Devil, timfaulkneri possessed an extremely thick jawbone enabling it to consume the bones and teeth of its prey. This species is related to the much smaller, previously discovered B. turnbulli (2.7 kg) – which until now was the only other undoubted thylacinid known from the late Oligocene.

The dentary and isolated first molar of B. timfaulkneri were recovered from Hiatus Site which is even older than Riversleigh’s White Hunter Site where B. turnbulli was previously found, making B. timfaulkneri the oldest undoubted thylacine discovered so far.

Badjcinus timfaulkneri is named after Tim Faulkner, the director and co-owner of the Australian Reptile Park and managing director of Aussie Ark. Tim has dedicated his life to the conservation of Australia’s wildlife including the largest still-living marsupial carnivore, the Tasmanian Devil.

The second new species is Nimbacinus peterbridgei. This was about the size of a Maltese Terrier (~3.7 kg). This species is represented by a near-complete dentary from White Hunter Site. Nimbacinus peterbridgei was a predator that probably focused on small mammals and other diverse prey species that lived with it in the ancient forests. Species of Nimbacinus appear to be more closely related to the Tasmanian Tiger than other thylacinids of similar age. This means Nimbacinus peterbridgei is probably the oldest direct ancestor of the Tasmanian Tiger yet known.

Nimbacinus peterbridgei was named after Australian geologist, speleologist and bibliophile Peter Bridge. He has devoted his life to helping uncover Australia’s ancient past, particularly in the caves of Western Australia.

The last species, Ngamalacinus nigelmarveni was a ~5.1kg thylacinid – approximately the size of a Red fox. It was also from White Hunter Site at Riversleigh. The blades on the lower molars of species of Ngamalacinus are elongated with deep V-shaped carnassial (‘meat-cutting’) notches, suggesting they were highly carnivorous – more so than any of the other thylacinids of similar size.

Ngamalacinus nigelmarveni is named after Nigel Marven, a renowned British television documentary presenter famous for paleontology-inspired series like Prehistoric Park and Sea Monsters.

The presence of three distinct lineages of specialised thylacinids during the late Oligocene highlights how quickly they diversified after first appearing in the fossil record. These thylacinids exhibits very different dental adaptations, suggesting there were several unique carnivorous niches available during this period. All but one of these lineages, the one that led to the modern Thylacine, became extinct around 8 million years ago.

That lineage of these creatures that survived for more than 25 million years ended with the death of Benjamin, the last Tasmanian Tiger in Hobart’s Beaumaris Zoo on the 7th of September 1936.

Professor Michael Archer, co-author
University of New South Wales
Sydney, New South Wales, Australia.

ABSTRACT
New thylacinid species of Badjcinus, Nimbacinus, and Ngamalacinus are described from upper Oligocene deposits of the Riversleigh World Heritage Area, northwestern Queensland. Badjcinus timfaulkneri, Nimbacinus peterbridgei, and Ngamalacinus nigelmarveni are among the oldest thylacinids yet known and indicate an earlier diversification of the family than previously understood. Maximum parsimony analysis supports a sister group relationship between Ng. nigelmarveni and Ng. timmulvaneyi, but the relationships of the two other new taxa are unresolved. Bayesian dated total evidence analysis using morphological and molecular data supports the generic assignment of B. timfaulkneri and Ng. nigelmarveni but not that of Ni. peterbridgei. Both phylogenies herein support a taxonomic reassignment of Thylacinus macknessi to the genus Wabulacinus, a conclusion also supported by the results of previous studies. Body mass estimates based on molar size regressions indicate body sizes ranging from 3.7 kg to 11.4 kg for the new thylacinid species. Badjcinus timfaulkneri exhibits an extremely deep jaw compared with other thylacinids, with mandibular bending strength analysis suggesting that it was a highly durophagous carnivore much like the modern dasyurid Sarcophilus harrisii. This analysis also suggests Ni. peterbridgei had a dentary more similar in shape to that of plesiomorphic thylacinid faunivores such as Ni. dicksoni and T. cynocephalus suggesting that it had a relatively more generalist faunivorous diet. The molars of Ng. nigelmarveni suggest they were better suited for longitudinal slicing than the molars of B. timfaulkneri and Ni. peterbridgei, indicating a more hypercarnivorous diet compared with that of those species.

INTRODUCTION
There are 12 extinct species in the dasyuromorphian family Thylacinidae, 10 of which are from the Oligo-Miocene (26–5.3 Ma) (Rovinsky et al., 2019). Unlike during the Plio-Pleistocene (5.3–0.12 Ma), which is dominated by large hypercarnivorous species of Thylacinus (15–55 kg), the Oligo-Miocene radiation exhibits considerably higher generic diversity, with seven monospecific clades known from the Riversleigh World Heritage Area in northwestern Queensland, all of which were between 3–10 kg in body mass. This restriction in size suggests thylacinids occupied most of the small- to medium-sized faunivorous niches at Riversleigh (1–10 kg). Contemporary peramelemorphians (∼50 g–1.5 kg) (Gurovich et al., 2014; Travouillon et al., 2013; Travouillon et al., 2010, 2014.1) and thylacoleonids (∼10–50 kg) (Gillespie, 2023; Gillespie et al., 2016, 2019.1a, 2019.2b) occupied relatively smaller and larger carnivore niches.

The oldest undoubted thylacinid, Badjcinus turnbulli Muirhead & Wroe, 1998, is known only from White Hunter Site in the Riversleigh World Heritage Area. This and other late Oligocene sites at Riversleigh have not yet been radiometrically dated. White Hunter Site is interpreted to be late Oligocene in age because of the presence of the ilariid Kuterintja ngama, otherwise only known from the Ngama Local Fauna from the Etadunna Formation, which is magnetostratigraphically dated to 24.8–25 Ma (Myers & Archer, 1997; Woodburne et al., 1994). Riversleigh’s Faunal Zone A (FZA) deposits contain taxa that support a late Oligocene age (Arena et al., 2016.1; Travouillon et al., 2006). The relatively plesiomorphic dentition of B. turnbulli has led to difficulty in taxonomic assignment, with phylogenetic analyses placing it either as a basally branching member of Thylacinidae (Kealy & Beck, 2017; Muirhead & Wroe, 1998; Murray & Megirian, 2006.1a; Wroe & Musser, 2001), as a stem dasyurid (Wroe et al., 2000), or as a sister group to Dasyuromorphia as a whole (Kealy & Beck, 2017).

Only two other thylacinid fossils are known from upper Oligocene deposits. Originally assigned to Nimbacinus dicksoni but later reassigned to Thylacinidae incertae sedis, an isolated m2 (QM F16809) from D-Site at Riversleigh is the only other thylacinid known from Riversleigh’s upper Oligocene deposits (Muirhead & Archer, 1989; Murray & Megirian, 2000.1; Wroe & Musser, 2001). An isolated, broken M2 (NTM P2815–10) of a thylacinid is also known from the Pwerte Marnte Marnte Local Fauna (LF) in the Northern Territory, a deposit assumed to be upper Oligocene on the basis of biocorrelation (Murray & Megirian, 2006.2b; Woodburne et al., 1994). Although this upper molar, which is similar in size to the putative thylacinid Mutpuracinus archibaldi, was suggested by Murray and Megirian (2006.2b) to be the oldest thylacinid in the fossil record, there are doubts about its identification as a thylacinid (see Discussion).

Nimbacinus dicksoni Muirhead & Archer, 1989, is the best preserved and researched Miocene thylacinid (Attard et al., 2014.2; Murray & Megirian, 2000.1; Wroe & Musser, 2001). Multiple specimens including a near complete skull and skeleton are known from Middle Miocene deposits at Riversleigh and from the Bullock Creek LF in the Northern Territory. The dentition of Ni. dicksoni is relatively more plesiomorphic than that of other thylacinids (except possibly Muribacinus gadiyuli) in retaining slightly reduced metaconids on m2–4 and unreduced stylar cusps on M1–3. Previous morphofunctional analyses of the skull of Ni. dicksoni suggest it was a voracious predator capable of hunting prey larger than itself, with biting capabilities most similar to extant species of Dasyurus, rather than to the larger Thylacinus cynocephalus (Attard et al., 2014.2).

In addition to Nimbacinus dicksoni, four monotypic thylacinid genera are known from upper and lower dentitions recovered from Early and Middle Miocene Riversleigh deposits. These include the medium-sized (∼5–7 kg) Wabulacinus ridei and Ngamalacinus timmulvaneyi Muirhead, 1997.1, as well as the diminutive (∼1–2 kg) Muribacinus gadiyuli Wroe, 1996, and the large (∼18 kg) Maximucinus muirheadae Wroe, 2001.1a (Myers, 2001.2). The dentition of Ng. timmulvaneyi, W. ridei, and Ma. muirheadae have been considered to be relatively plesiomorphic in comparison with species of Thylacinus, but more derived than Ni. dicksoni (Muirhead, 1997.1). The diminutive Mur. gadiyuli is dentally the most plesiomorphic thylacinid known (Wroe, 1996).

Thylacinus macknessi Muirhead, 1992, from Riversleigh’s Early Miocene Neville’s Garden Site, is tentatively regarded as the earliest known member of the genus Thylacinus (Muirhead & Gillespie, 1995). This taxon possesses unique dental adaptations associated with a shift within the Thylacinus lineage towards hypercarnivory, including near complete loss of metaconids on m2–4, loss of entoconids, reduction of the lingual portion of the talonid margin in m2–4 and a lingual shift of the hypoconid so that the cristid obliqua forms a continuous longitudinal blade with the paracristid.

The powerful thylacine, T. potens Woodburne, 1967, from the Alcoota Local Fauna in the Northern Territory, has been interpreted on the basis of biocorrelation to be Late Miocene between 8.5 and 5.5 Ma (Megirian et al., 1996.1, 2010.1). It is the largest and most hypercarnivorous thylacinid known. It has been estimated to be between 30–56 kg in adult body mass (Myers, 2001.2; Wroe, 2001.1a), with some estimates exceeding 120 kg (Yates, 2014.3). Two additional species of Thylacinus with dental adaptations for increased carnivory, T. yorkellus and T. megiriani, are known from Upper Miocene to Lower Pliocene deposits (Murray, 1997.2; Yates, 2015).

Tyarrpecinus rothi Murray & Megirian, 2000.1, is a small thylacinid from the Late Miocene Alcoota Local Fauna of the Northern Territory. It is known from a broken maxilla that retains P2 and an isolated M2. The phylogenetic relationships and paleobiology of this taxon cannot be confidently determined until more complete craniodental material is found.

The quoll-sized Mutpuracinus archibaldi Murray & Megirian, 2000.1, known from a near complete skull with an incomplete upper and lower dentition from the Middle Miocene Bullock Creek LF in the Northern Territory (Murray & Megirian, 2006.1a), was initially considered to be an early thylacinid because of craniodental and basicranial similarities to plesiomorphic thylacinids such as Ni. dicksoni. However, more recent phylogenetic analyses suggest it should be regarded as Dasyuromorphia incertae sedis because of its lack of craniodental synapomorphies uniting it with undoubted thylacinids (Churchill et al., 2023.1; Kealy & Beck, 2017; Rovinsky et al., 2019).

Two further medium-sized (1–10 kg) incertae sedis dasyuromorphians are known from Miocene deposits; Whollydooleya tomnpatrichorum Archer, Christmas et al., 2016.2, from Miocene deposits in New Riversleigh (an area approximately 10 km southwest of the Riversleigh World Heritage Area) and Apoktesis cuspis Campbell, 1976, from upper Oligocene deposits at Lake Ngapakaldi in the Tirari Desert of South Australia. Either may be related to thylacinids or dasyurids (Archer, Christmas et al., 2016.2; Campbell, 1976). However, the lack of adequate fossil material to critically assess the relationships of these two enigmatic taxa precludes a more precise assignment beyond Dasyuromorphia incertae sedis. Whollydooleya tomnpatrichorum is only known from a single lower molar while the location of the skull and dentaries attributed to A. cuspis is currently unknown.

In this study, we describe three new species of thylacinid from Riversleigh’s oldest deposits: the upper Oligocene Hiatus and White Hunter Sites. The fossil specimens herein are all dentaries retaining near complete or partial lower dentitions.

Of course, it would be stupid to assume the Bronze Age pastoralists who wrote the Bible knew anything about Australia, or even a southern hemisphere. Since they believe Earth was a small flat place with a dome over it, they wouldn't even have considered hemispheres, northern of southern. Their view of the world was so narrow and restricted they thought all they had to explain was the small area within a day or two's walk of the Canaanite Hills, so nothing outside that small area was included; not an animals, mountain, continent or people; nothing.

So, the idea that they would have believed the Tasmanian tiger was magically created without ancestors 10,000 years ago or less is utterly preposterous and could only be believed by someone at least as blind to the evidence as were the authors of Genesis.

Refuting Creationism - How Mediterranean Biodiversity Evolved - 5.5 Million Years Before 'Creation Week'

Marine sediments hosting abundant fossils dated in the Late Miocene, from about 8 to 7 million years ago.

Credit: Konstantina Agiadi

Fig. 2: Reconstruction of a marine landscape of the Early Pliocene (5.1-4.5 million years ago)

Art © Alberto Gennari.

How a salt giant radically reshaped Mediterranean marine biodiversity

Because they were so ignorant of the history of their part of the world, the origin myths made up by the Bronze Age authors of Genesis, told us nothing about the rich history of the sea that was almost on their doorstep, and the one in which they set daft tales like that of Jonah - the Mediterranean.

The Mediterranean Sea (the sea in the Middle of the Earth to the Romans) was central to history of the Middle East, Western Europe and North Africa but few people then could have been aware that the sea itself is a mere (on a geological timescale) 5.5 million years old in its present form.

It was formed firstly by the African plate pushing north towards Eurasia causing a water-filled depression to form that was originally connected to the Atlantic Ocean, but, as Africa pushed further north, causing mountains in modern-day Morocco and Spain to rise up, the Mediterranean became isolated and, with low inflow and high temperatures, what had been the Mediterranean Sea became a salt-filled depression, known to geologists as the Messinian Salinity Crisis (MSC) when the sea dried up leaving a thick deposit of salt and gypsum and of course exterminating just about all marine life.

Recreation of one of the proposed models for how the Mediterranean was isolated by the sinking of a lithospheric plate into the Earth’s mantle (approx. 6 million years ago) and how dry climate then lead to the desiccation of that sea during the Messinian Salinity Crisis (approx. 5.5 million years ago), until 5.33 million years ago, the level of the Atlantic exceeded that of the Gibraltar land bridge and triggered a fast refill.

© CSIC - Daniel García-Castellanos.

This was ended abruptly when the Atlantic Ocean broke through at the Western end in what is now the Straits of Gibraltar when the Mediterranean basin refilled extremely quickly, possible in a few months to two years.

Refuting Creationism - How a Mass Extinction 66 Million Year Before Creation Week Triggered The Rappid Evolution Of Birds

The Broad-billed Tody, Todus subulatus, is a member of the bird group Coraciimorphae.

Image credit: Daniel Field,
University of Cambridge

The Northern Flicker, Colaptes auratus, is a member of the bird group Coraciimorphae. Berv and co-authors identify this group of birds and others as having close ties to the end-Cretaceous mass extinction that occurred in the wake of the Chicxulub asteroid impact approximately 66 million years ago.

Image credit: Daniel Field, University of Cambridge

Mass extinction 66 million years ago triggered rapid evolution of bird genomes | University of Michigan News

Another major milestone in the history of life on Earth happened, like almost everything else, in that long pre-Creation Week history that creationists need to ignore. It was the mass extinction about 66 million years ago that killed the non-avian dinosaurs and most megafauna, leaving vacant niches that could be exploited by the descendants of survivors. It's no surprise to anyone who understands how evolution works, that this led to a proliferation of new species as existing species diversified to fill those niches.

That much was known already from the fossil record, but now a University of Michigan study has found how this maps onto changes in the genome of the major bird families, as a kind of DNA fossil, just as the TOE predicts.

The major difference between the different taxons is how developed the chicks are on hatching and how dependent they are on their parents. In ducks, geese, the ratites and ground-nesting birds such as the plovers, chickens and turkeys, the chicks are mobile and able to feed themselves (precocial) almost as soon as they've hatched. At the other end of the scale, many passerines are helpless on hatching and are entirely dependent on their parents for food and shelter (altricial) for several weeks.

As the birds evolved and diversified, they tended to become smaller and also more altricial. This reduction in body size and increased altriciality are reflected in the genomes. It was these transitional changed that the researchers detected.

These major changes were occurring within 3-5 million years after the mass extinction.

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.

Refuting Creationism - Evolution Observed As Killifish On Trinidad Respond To Predation

A stream in Trinidad, typical killifish habitat

Killifish are highly adaptable to their surroundings

Fish adjust reproduction in response to predators - News Center - The University of Texas at Arlington

The killifish on the Caribbean island of Trinidad are ideal subjects for studying evolution because they can quickly adapt to environmental change. Some have even become amphibious, spending time out of water, probably to avoid predation, while others lay their eggs out of water on damp moss as an evolved adaptation to predation. However, eggs out of water bear the additional risk of desiccation which needs to be balanced against the risk of predation in water.

This paper by Professor Matthew R. Walsh, a biology professor at the University of Texas at Arlington, Arlington, TX, USA and his laboratory technician, Christopher Roden shows that the eggs of fish that lay them out of water hatch earlier than those in water, reducing the risk of desiccation, showing how predation has driven a change in the rate of embryo development to reduce the risk of desiccation, while avoiding predation.

Their findings are published open access in Proceedings of the Royal Society B and explained in the University of Texas press release:

Refuting Creationism - Why Ammonites Went Extinct - 66 Million Years Before 'Creation Week'

Ammonites basking under the Late Cretaceous sun

Artwork by Callum Pursall (@cpursall on X)

Ammonites basking under the Late Cretaceous sun.>

Artwork by Callum Pursall (@cpursall on X)

June: Ammonites wiped out with dinosaurs | News and features | University of Bristol

Yet more evidence incidentally refuting creationism was published two days ago in the journal Nature Communications. That wasn't the intention of the palaeobiologists who presented them, of course, but the facts they presented simply did that by being entirely inconsistent with creationism and at variance with what the facts would be if creationism had any merit.

The paper, by a research team led by palaeontologists at the University of Bristol, concerns the extinction of the ammonites, apparently very suddenly on a geological time-scale. It had previously been thought that their decline had been a slow, gradual process but the evidence found by the researchers is that it was as sudden as that of the non-avian dinosaurs and caused by the same random astronomical event - a meteor strike, 66 million years ago.

The resulting climate change caused a mass extinction at the end of the Cretaceous and the start of the Palaeogene - the so-called K-Pg boundary. (K for Kreidezeit - German).

The ammonites were cephalopod molluscs related to octopuses, squids and the nautiluses and were a major predator in Cretaceous seas. Judging by the abundance of their fossils which I have picked up in fields in Buckinghamshire, they were common and widespread. On holiday some years ago on the north coast of Somerset, my children and I once spent several hours on the beach at Watchet, breaking open pieces of slate to discover ammonites inside them. My children were excited to think they were the first humans to look at each ammonite as we exposed them for the first time in maybe 100 million years.

However, when it comes to assessing the abundance and diversity of extinct orders such as ammonites, local abundance or rarity can be misleading, because it can lead to sampling bias where a local collection of fossils can be mistaken for a general abundance and a local absence can be wrongly extrapolated to indicate a general scarcity. The authors used techniques to minimise this bias in their reassessment of the rate of extinction of ammonites.

Refuting Creationism - The 40-Million-Year History of Biodiversity in The Indo-Australian Archipelago

Vibrant marine life in the Coral Triangle region of Sabah, Malaysia, showcasing the area's remarkable biodiversity.

Photo credit: David M. Baker.

Stunning coral formations captured in the waters of the Coral Triangle, Sabah, Malaysia.

Photo credit: David M. Baker.

HKU Ecologists Reconstruct the History of Biodiversity in the Indo-Australian Archipelago and its Rise as a Hotspot - Press Releases - Media - HKU

If you're a creationist fraud trying to fool more scientifically-illiterate simpletons into joining your cult and giving you money so you don't need to earn an honest living, the last thing you need is this constant deluge of evidence refuting your claims that Earth is only a few thousand years old and everything on it was magically created as it is today.

And yet here we have yet another refutation in the form of a research paper detailing the 20-million-year history of one of the most biodiverse places on Earth - the 'Indo-Australian Archipelago', also called 'The Coral Triangle'.

The Indo-Australian Archipelago has been described as a biodiversity hot-spot because it contains so many examples of radiating evolution over the last 20 million years.

Creationism in Crisis - How Homo Sapiens Helped Bonelli's Eagle Extend Its Range - 40,000 Years Before Creation Week

Bonelli's Eagle, Aquila fasciata

F. David Carmona

Bonelli's Eagle, Aquila fasciata

F. David Carmona

Early "Homo sapiens" facilitated the establishment of the Bonelli's eagle in the Mediterranean 50,000 years ago - Canal UGR

Not only is there no sign at all that the conversion of leading biologists to creationism's childish fairy tale in place of the scientific Theory of Evolution, that creationist cult leaders have been assuring their dupes is imminent - and has been for the last 50 years or so - it's as though they've never even heard of it. They still keep finding evidence of events that happened ten of thousand, even tens of millions of years before the Universe existed, according to the ludicrous creation myths they are supposedly about to adopt. And those events are frequently evidence of evolution or recent human history.

Imagine a serious, grown-up scientist who has been through university, with so much contrary information at his or her fingertips believing that account of magic creation 10,000 years ago written by ignorant Bronze Age pastoralists yet belonging to the creation cult requires fools to believe such an absurdity.

About 9 months ago while on holidat near Bezier, France, we were driving to Carcassonnes when, about a mile apart, we saw two majestic eagles that neither of us recognised. I now know they were Bonelli's eagles, and I probably have the activities of early Homo sapiens about 40,000 years ago to thank for them being there.

A study led by scientists from the University of Granada (UGR), Spain, shows how the activities of early Homo sapiens in the Iberian Peninsula, 40,000 years before creationists think their god created a universe consisting of a small, flat planet with a dome over it in the Middle East, may well have facilitated the expansion of the range of Bonelli's Eagle, Aquila fasciata, north of the Mediterranean Basin.

Creationism in Crisis - How The Human Heart Evolved As Humans Adapted To An Active Life-Style

Study on architecture of heart offers new understanding of human evolution - Swansea University

According to research by an international team from Swansea University, Swansea, Glamorgan, Wales and the University of British Columbia, Okanagan, Canada, there is evidence that the human heart has evolved to facilitate the more active life-style of humans compared to their closest relatives, as they diversified.

Humans typically have a much more active life-style with a higher resting metabolic rate compared to chimpanzees. We also have larger brains. As hunter-gatherers, we typically walked and ran far more often and for much longer than do the other apes and we needed to lose the excess body heat this activity generated, so we needed a more hemodynamic heart able to meet those needs, which meant adaptations to changes in the twisting of the left ventricle (LV) - the chamber which pumps oxygenated blood around the body - during systole, and this meant a change in the degree of trabeculation inside the LV.

In the context of heart ventricles, what are trabeculae and what is their function? Trabeculae (also known as trabeculae carneae) are irregular ridges of muscle found on the inner walls of the ventricles of the heart. They play several important roles in the function of the heart:

1. Structural Support: Trabeculae carneae help reinforce the ventricular walls. Their irregular structure provides additional strength and prevents the walls from sticking together during contraction, thereby maintaining the heart's shape and integrity.
2. Facilitation of Blood Flow: The trabeculae carneae create a more turbulent flow of blood within the ventricles, which can help with the efficient mixing of blood and ensure a more thorough contraction and expulsion of blood from the ventricles during systole.
3. Conduction System: Some trabeculae carneae are involved in the conduction system of the heart. For example, the moderator band (a type of trabecula) in the right ventricle contains part of the right bundle branch of the bundle of His. This helps coordinate the contraction of the right ventricle by ensuring that the electrical impulses are transmitted efficiently.
4. Reduction of Blood Stagnation: By creating a complex surface within the ventricles, trabeculae carneae reduce the likelihood of blood stagnation, which can prevent clot formation and improve overall blood flow dynamics.

In summary, trabeculae carneae serve to strengthen the ventricular walls, enhance blood flow, support the heart's electrical conduction system, and reduce the risk of blood clots by preventing blood from pooling in the ventricles.

What is meant by 'ventricular twist'?

'Ventricular twist' refers to the complex motion of the heart's ventricles during the cardiac cycle, particularly during the contraction (systole) and relaxation (diastole) phases. This twisting motion is also known as 'ventricular torsion' or 'ventricular rotation.' Here’s a more detailed explanation:

Mechanics of Ventricular Twist

1. Twisting Motion During Systole: During systole, the ventricles contract to pump blood out of the heart. The base (the top part of the ventricles, near the atria) of the heart rotates in a counterclockwise direction (when viewed from the apex), while the apex (the bottom tip of the heart) rotates in a clockwise direction. This results in a wringing motion, similar to wringing out a wet towel.
2. Untwisting Motion During Diastole: During diastole, the ventricles relax and fill with blood. The previously twisted ventricles now untwist, helping to create a suction effect that aids in the efficient filling of the ventricles with blood.

Significance of Ventricular Twist

1. Efficient Blood Ejection: The twisting motion enhances the efficiency of the heart’s pumping action. By adding a rotational component to the contraction, the heart can expel blood more forcefully and completely.
2. Diastolic Suction: The untwisting or recoil of the ventricles during diastole contributes to the rapid filling phase. This elastic recoil generates a negative pressure that helps draw blood into the ventricles more efficiently.
3. Mechanical Synchrony: The coordinated twisting and untwisting ensure that the contraction and relaxation phases are well-synchronized, promoting optimal cardiac function and maintaining a steady and efficient blood flow throughout the body.
4. Clinical Relevance: Abnormalities in ventricular twist mechanics can be indicative of various cardiac pathologies, such as heart failure, myocardial infarction, or cardiomyopathies. Therefore, measuring and analyzing ventricular twist can provide valuable diagnostic and prognostic information.

Measurement of Ventricular Twist
Ventricular twist can be assessed using advanced imaging techniques such as speckle-tracking echocardiography (STE) or cardiac magnetic resonance imaging (MRI). These techniques allow for detailed visualization and quantification of the rotational mechanics of the heart.

In summary, ventricular twist is a crucial aspect of the heart’s mechanics, contributing to the efficient ejection and filling of blood in the ventricles. It is essential for maintaining optimal cardiac function and can be an important parameter in the assessment of heart health.

The team has shown there is a negative correlation between the degree of trabeculation and LV systolic twist. The inner wall of the LV of a healthy human heart is comparatively smooth. Their results are published in the journal Communications Biology and explained in a Swansea University News release:

An international research team from Swansea University and UBC Okanagan (UBCO) has uncovered a new insight into human evolution by comparing humans’ hearts with those of other great apes.

Despite humans and non-human great apes having a common ancestor, the former has evolved larger brains and the ability to walk or run upright on two feet to travel long distances, likely to hunt.

Now, through a new comparative study of the form and function of the heart, published in Communications Biology, researchers believe they have discovered another piece of the evolutionary puzzle.

The team compared the human heart with those of our closest evolutionary relatives, including chimpanzees, orangutans, gorillas, and bonobos cared for at wildlife sanctuaries in Africa and zoos throughout Europe.

During these great apes' routine veterinary procedures, the team used echocardiography—a cardiac ultrasound—to produce images of the left ventricle, the chamber of the heart that pumps blood around the body. Within the non-human great ape's left ventricle, bundles of muscle extend into the chamber, called trabeculations.

The left ventricle of a healthy human is relatively smooth, with predominantly compact muscle compared to the more trabeculated, mesh-like network in the non-human great apes. The difference is most pronounced at the apex, the bottom of the heart, where we found approximately four times the trabeculation in non-human great apes compared to humans.

Bryony Curry, first author
Centre for Heart, Lung and Vascular Health
School of Health and Exercise Sciences
University of British Columbia, Kelowna, BC, Canada.

The team also measured the heart's movement and velocities using speckle-tracking echocardiography, an imaging technique that traces the pattern of the cardiac muscle as it contracts and relaxes.

We found that the degree of trabeculation in the heart was related to the amount of deformation, rotation and twist. In other words, in humans, who have the least trabeculation, we observed comparatively greater cardiac function. This finding supports our hypothesis that the human heart may have evolved away from the structure of other non-human great apes to meet the higher demands of humans’ unique ecological niche.

Bryony Curry.

A human’s larger brain and greater physical activity compared to other great apes can also be linked to higher metabolic demand, which requires a heart that can pump a greater volume of blood to the body.

Similarly, Higher blood flow contributes to humans’ ability to cool down, as blood vessels close to the skin dilate—observed as flushing of the skin—and lose heat to the air.

In evolutionary terms, our findings may suggest selective pressure was placed on the human heart to adapt to meet the demands of walking upright and managing thermal stress.

What remains unclear is how the more trabeculated hearts of non-human great apes may be adaptive to their own ecological niches. Perhaps it’s a remaining structure of the ancestral heart, though, in nature, form most often serves a function.

Dr Aimee Drane, co-corresponding author
International Primate Heart Project
Cardiff Metropolitan University, Cardiff, UK
And Faculty of Medicine
Health and Life Sciences
Swansea University, Swansea, UK

The research team is grateful to the staff and volunteers who care for the animals in the study, including the teams at Tchimpounga Wildlife Sanctuary (Congo), Chimfunshi Wildlife Sanctuary (Zambia), Tacugama Chimpanzee Sanctuary (Sierra Leone), Nyaru Menteng Orangutan Rescue and Rehabilitation Center (Borneo), the Zoological Society of London (UK), Paignton Zoo (UK), Bristol Zoo Gardens (UK), Burgers’ Zoo (Netherlands) and Wilhelma Zoo (Germany).

Abstract
Although the gross morphology of the heart is conserved across mammals, subtle interspecific variations exist in the cardiac phenotype, which may reflect evolutionary divergence among closely-related species. Here, we compare the left ventricle (LV) across all extant members of the Hominidae taxon, using 2D echocardiography, to gain insight into the evolution of the human heart. We present compelling evidence that the human LV has diverged away from a more trabeculated phenotype present in all other great apes, towards a ventricular wall with proportionally greater compact myocardium, which was corroborated by post-mortem chimpanzee (Pan troglodytes) hearts. Speckle-tracking echocardiographic analyses identified a negative curvilinear relationship between the degree of trabeculation and LV systolic twist, revealing lower rotational mechanics in the trabeculated non-human great ape LV. This divergent evolution of the human heart may have facilitated the augmentation of cardiac output to support the metabolic and thermoregulatory demands of the human ecological niche.

Introduction
Mammals are a remarkably diverse class of vertebrates, capable of inhabiting every major biome on the planet. This diversity is associated with a vast range of environmental stressors and interspecific differences in posture and locomotion, creating very different hemodynamic challenges. Despite this remarkable diversity, the gross structure of the mammalian heart is highly conserved across species; retaining four chambers and a complete interatrial and interventricular septum¹.

Although the gross structure of the mammalian heart is conserved, interspecific features exist. For example, heart shape varies considerably across species, from broad and flat in whales to long and narrow in terrestrial ungulates2. Variation in the cardiac phenotype is also present among closely-related mammals², indicative of evolutionary divergence. While comprehensive data examining cardiac structure and function across the entire Hominidae taxon do not exist, preliminary work suggests that the left ventricle (LV) of adult male chimpanzees (Pan troglodytes) may be morphologically distinct from that of humans³. Prominent myocardial trabeculations, characterized by protrusions of the endocardium into the LV cavity with intertrabecular recesses, were previously observed in adult male chimpanzees³. This trabeculated phenotype differs from the relatively smoother ventricular wall typically observed in healthy humans⁴, suggesting that there may have been species-specific selective pressures on the heart during the evolution of Hominidae³.

Cardiac morphology and function are closely linked⁵; therefore, the discrete structural attributes of the chimpanzee and human LV likely coincide with differences in systolic and diastolic ventricular function. Such interspecific cardiac phenotypes may be the result of selection for the hemodynamic demands associated with each species’ ecological niche (i.e., the habitat and the role a species plays within an ecosystem). Indeed, previous data has shown that resting metabolic rate⁶, physical activity and daily locomotion⁷ are far greater in humans in comparison with other great apes, and so it is not surprising that cardiac output is also comparatively higher in humans³. The larger cardiac output in humans is likely supported by comparatively greater LV systolic and diastolic function (e.g., myocardial rotation and deformation), including LV twist³. LV twist, which is dependent upon the helical angulation of the aggregated cardiomyocytes^8,9,10, is characterized by counter-directional rotation of the LV base and apex during systole. Together with the velocity of LV untwisting during diastole, LV twist helps facilitate efficient filling and ejection of the ventricle, especially during periods of heightened metabolic and thermoregulatory demand^11,12.

The functional advantages associated with a LV capable of greater twist and untwisting velocity, combined with the preliminary data in adult male chimpanzees³, prompt the hypothesis that the human heart has diverged from a trabeculated ancestral phenotype to support the specific metabolic and thermoregulatory demands of the human niche. To test this hypothesis, we compared LV structure across all extant great apes using 2D echocardiography and further explored trabeculation in a subset of post-mortem chimpanzee (Pan troglodytes) hearts. We then compared LV rotation and deformation between human and non-human great apes to explore whether the trabeculated phenotype is associated with differences in LV systolic and diastolic functional mechanics. Our findings point to evolutionary divergence of the human LV away from the phenotype of all other non-human great apes, which may have had important implications for cardiac function in early humans.

Discussion (part of)

[…]

Collectively, the findings of this study support evolutionary divergence of the human LV away from a trabeculated ancestral phenotype, towards a ventricular wall with a proportionately greater compact myocardium. We propose that this adaptive evolution occurred to support the requirements of the human ecological niche, including an augmented cardiac output to facilitate sustained bipedal physical activity, a larger brain, and the associated metabolic and thermoregulatory demands.

Fig. 1: Comparison of left ventricular trabeculation in great apes.

The bullseye plots represent the trabecular:compact (T:C) ratio for each segment of the left ventricle. The outer layer of the bullseye plots represents the basal segments, the middle and innermost layers represent the midpapillary and apical segments of the left ventricle, respectively. Red segments correspond to an average T:C ratio of >2; orange segments correspond to an average T:C ratio >1.5–2; yellow segments correspond to an average T:C ratio of >1–1.5; green segments correspond to an average T:C ratio of >0.5–1; blue segments correspond to an average T:C ratio of <0.05. Echocardiographic images of the parasternal short-axis at the apex are shown at end-diastole. *No data were available for the basal or midpapillary segments in the orangutans due to artifact from laryngeal air sacs. †These T:C ratios compare favorably with other reports in healthy human cohorts, ranging from 0.2 to 0.9^65,66. ‡Anatomical labels have been provided in accordance with the conventional guidelines for cardiac chamber quantification by the American Society of Echocardiography and European Association of Cardiovascular Imaging⁵². However, we note that this clinical convention does not align with the recognized anatomical approach and may result in confusion across disciplines—see ref. ⁶⁷ for further clarification.

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Fig. 2: Graphical representation of the trabecular:compact (T:C) ratio for each segment of the left ventricle in chimpanzees.

The outer layer of the bullseye plots represents the basal segments, the middle and innermost layers represent the midpapillary and apical segments of the left ventricle, respectively. Red segments correspond to an average T:C ratio of >2; orange segments correspond to an average T:C ratio >1.5–2; yellow segments correspond to an average T:C ratio of >1–1.5; green segments correspond to an average T:C ratio of >0.5–1; blue segments correspond to an average T:C ratio of <0.05. Infant age class includes individuals of ≤4 years of age, juveniles between 5–7 years of age, sub-adults between 8-11 years of age and adults ≥12 years of age.

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Fig. 3: Comparison of left ventricular morphology and mechanical indices of ventricular function between chimpanzees and humans.

Shortening along the long axis of the left ventricle (i.e., longitudinal strain) and deformation at the apex (i.e., apical circumferential and apical radial strain) were averaged across a mixed-sex, adult cohort of chimpanzees (n = 136) and represented in maroon. Blue reflects the deformation patterns of a mixed-sex, adult human cohort (n = 34). Dashed line represents aortic valve closure. Gray shading to the left of dashed line represents systole and white represents diastole.

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Fig. 4: Relationship between markers of left ventricular (LV) function and apical trabeculation in the extant Hominidae taxon.

a Peak LV systolic apical rotation, shown in red, in a mixed-sex, adult cohort of humans (male n = 18, female n = 16), chimpanzees (male n = 59, female n = 51), bonobos (male n = 2, female n = 4), gorillas (male n = 4, female n = 6) and orangutans (male n = 10, female n = 6). b Peak LV systolic twist, shown in green, and (c) peak diastolic untwisting velocity, shown in blue, in a cohort of humans (male n = 18, female n = 16), chimpanzees (male n = 47, female n = 43), bonobos (male n = 1, female n = 3) and gorillas (male n = 4, female n = 5). Analyses of LV twist and untwisting velocity were not possible in all individuals, nor any of the orangutans due to artifacts from laryngeal air sacs, hence the reduced sample size. The exponential plateau curve is shown, with the 95% confidence bands represented by the dotted line. The mean and standard error are shown in black for each species.

Curry, B.A., Drane, A.L., Atencia, R. et al.
Left ventricular trabeculation in Hominidae: divergence of the human cardiac phenotype. Commun Biol 7, 682 (2024). https://doi.org/10.1038/s42003-024-06280-9

Copyright: © 2024 The authors.
Published by Springer Nature Ltd. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

No crumbs of comfort there for creationists as the authors attribute everything to evolution by natural selection as humans diverged from the other great apes, nor is there any hint of a doubt that such an evolutionary divergence occurred.

The interesting thing from a biologists point of view is how the changes to the human heart reflect changes in our life-style as we adopted an upright gait and a hunter-gatherer life-style, necessitating running and walking long distances with additional demands on our heart to cope with the additional oxygen required and to dissipate the excess heat these activities generated, in addition to the increased demands our large brains were already imposing on our circulatory and thermoregulatory systems.

More work is now needed to understand whether the retention of this degree of trabeculation in the other apes has a benefit or whether it has simply been retained from a common ancestor. If the former, what evolutionary trade-off has there been for humans in losing these benefits?