Nature is Thriving in an Age of Mass Extinction

Challenging Conventional Wisdom on Biodiversity Loss

There is a worldview that humans are killing the earth, that the colonizing conquest of capitalism is a runaway train, veering towards various ecological tipping points and collapse.  

Freud wrote extensively about why annihilation anxiety is so seductive. He reasoned that stories of collective death allow our unconscious minds to process what cannot be processed. Our deaths. These stories are cathartic. They riddle Hollywood films, popular media, the Book of Revelations, Shakespeare's plays; you name it. In short, they sell. So the question becomes, what narrative does the data support?

Examining the Evidence

Human activity has had significant impacts on the earth. We caused the extinction of many large land mammals and our genetic competitors, such as Neanderthals and Homo Erectus, thousands to tens of thousands of years ago. During the Age of Discovery, we also triggered the extinction of many flightless and disease-prone birds on isolated islands. Today, many mammals, cacti, corals, amphibians, and birds are threatened (IUCN red list). However, there is hope, as conservation efforts have led to the recovery of many beloved species of late. It is worth noting that extinction as a concept did not exist until 1705, when Mastodon fossils were discovered, after many of the recorded extinctions below.

The International Union for Conservation of Nature (IUCN) and the Committee on Recently Extinct Organisms (CREO) at the American Museum of Natural History maintain the official record of extinct and endangered species. While both datasets are similar, CREO excludes birds and endangered species. IUCN emphasizes that they may be undercounting extinctions. Out of 1.9 million documented species, 902 are extinct, 9,000 are critically endangered, and 42,000 are endangered. Most of the extinct species are freshwater mollusks (e.g., snails). These numbers are small compared to documented species and even smaller compared to the estimated 9-10 million species on earth (Encyclopedia of Life). In this light, calling the Anthropocene the 6th mass extinction appears premature.

Of the recorded extinctions, the majority took place on islands:

• 95% of all mammal extinctions took place on islands

• 95% of bird extinctions took place on islands

• 90% of reptile extinctions took place on islands

• 70% of mollusk extinctions took place on islands. 

• The extinction rate is in line with the background rate on continents but is orders of magnitude greater on islands (source).

The majority of the extinctions in the data can be ascribed to European navigators introducing rats, cats, goats, and diseases to remote islands in the 15th century. Many of these extinct species were quite literally sitting ducks that were overhunted. While calamitous, it bears noting that the island ecosystems did not collapse in the wake of these events. Instead, they evolved in different forms. 

In general, most claims of global biodiversity loss suffer from the problem of scale. Reliance is placed on data from islands and other restricted localities and extrapolated to the size of the entire globe. Professor John C Briggs of the University of Oregon

There are disconnects at play here. How do we arrive at the notion that a 6th mass extinction is underway? (there have been five mass extinctions in the geologic record). Why does the World Wildlife Fund estimate species extinction to be between 1,000 and 10,000 times higher than natural extinction rates? Are they conflating the island extinction rates, representing 3% of the earth's landmass, with continental extinctions? What supports the UN reporting that Humans are driving one million species to extinction? That is half of the documented species on earth — a bold claim if unsupported by data.

A Flawed Formula

Enter stage left the species-area relationship (SAR) theory developed by Robert MacArthur and E. O. Wilson in the 1960s. They observed that the size of an island was proportionate to the number of species on the island and found this relationship can be consistently predicted by the equation S = cA^z, where S is the number of species, A is the area of the island, c is a constant, and z is a scaling exponent.

E.O Wilson, perhaps the most influential ecologist since Darwin, applied his island equation to the rainforest, where clear-cutting was emerging at an alarming rate in the 70s and 80s. He suggested that ~ 27,000 rainforest species would go extinct each year as a result of the habitat destruction, with the majority being insects. A direct math output from the equation he developed on islands with Macarthur in the 60s.

To this day, sources projecting large extinction numbers are doing so based on SAR modeling & theory rather than empirical evidence. This is complicated because invertebrates don't appear in the fossil record, so we have very little intel on insect extinctions. IUCN has assessed only 1% of the one million documented insect species. If an insect goes extinct in the forest, and no one is there to record it, does that mean it didn't happen? 

While this ontological loop feels compelling, data must validate the theory, not the other way around. That is the scientific method. If millions of insect species at the base of the food pyramid have gone extinct over the intervening decades, then extinctions at the top of the food pyramid would manifest. In fact, no continental bird or mammal is recorded to have gone extinct due to habitat reduction thus far (source). 

However, a few species have gone extinct in the wild and now live in captivity. Principally in, Brazil's coastal Atlantic forests, which hold nearly all of Brazil’s human population, have seen a 93% natural habitat reduction and contain the greatest concentration of endangered species on earth (source). 60% of Brazil’s endangered species come from this thin coastal slice of temperate, tropical, and mangrove habitats — not from the more famous Amazon basin. This area is ground zero for agricultural clear-cutting in Brazil.

As rainforest ecologist Nigel Stork, then at the University of Melbourne, pointed out in a groundbreaking paper in 2009, if the SAR formula worked as predicted, up to half the planet's species would have disappeared in the past 40 years. And they haven't. "There are almost no empirical data to support estimates of current extinctions of 100, or even one, species a day," he concluded.

As one of the few classical laws of ecology, SAR’s limits are perhaps analogous to Newtonian Mechanics breaking down at very small or fast domains. Rainforest species are significantly more mobile and resilient than island species. Island species often lack predators, and devolve over time, sometimes losing the ability to fly, evade predators, or combat disease. Rainforest species, on the other hand, live in a Darwinian pressure cooker. Comparing the two is like comparing NBA players to an after-work pick-up league. 

Frogs on the Frontline

The plight of Amphibians is the best argument that we are in a 6th extinction. This class of vertebrates has survived four mass extinction events over 340 million years, and yet, are precipitously declining in numbers. Over the past few decades, 168 of 8,700 known species are believed to have gone extinct, and over 43% have declining populations (source). A 2013 study found that population loss in the United States is proceeding at a staggering annual rate of 3.7%, with red-listed amphibians dropping even faster, at 11.6% per year (source).

While alarming, these losses have coincided with a global outbreak of Chytridiomycosis, deemed "the worst infectious disease ever recorded among vertebrates." Imagine if COVID led to cardiac arrest nearly 100% of the time and if our skin was a highly susceptible physiological organ that we used to breathe and drink water with. As if wearing our lungs inside-out as a shell for our bodies. Layer in that the disease is a global fungal pathogen, Batrachochytrium dendrobatidis (Bd for short), and you have the amphibian equivalent of the hit zombie TV series 'The Last of Us'. This is a froggy nightmare. 

Elizabeth Kolbert places this drama center stage in her book The 6th Extinction. She tracks herpetologists into the jungles of Central America, ground zero for Bd colony collapse, and suggests that an entire branch of the tree of life is being axed off at the root. But while her Pulitzer prize-winning book was published in 2014, it turns out that by 2018, Central American frogs began developing resistance to the disease (source). Likewise, Frogs in Australia (source) and salamanders in Europe (source). All over the world, they’ve begun secreting antimicrobial peptides to fight the fungus pathogen upon contact with their skin.

The most threatened genus of frogs from the cloud forests of Ecuador and Colombia, also shows signs of genetic adaptations to Db (source). It was thought that over 80% of the Harlequin line was lost due to Db. However, a Ph.D. student named Kyle Jaynes, with the help of a five-person team, rediscovered 32 of the 87 previously presumed extinct species in five locations. He noted that these species had only been extinct to scientists and that indigenous tribes, who treasure harlequin frogs, had kept track of their whereabouts. While re-discovery does not equal recovery, this story raises questions about the speed with which herpetologists declare a species extinct and highlights the difficulties of conducting fieldwork in mountainous rainforests.

The ecological apocalypse argument seems to be that as humans trigger acute change, so follows a 6th extinction led by frogs. Frogs are the litmus. But as a counterargument, amphibians are susceptible to environmental changes. Yes. And precisely because of that sensitivity, they evolve quickly under duress. They genetically iterate. It seems logical that this would be an evolutionary advantage—a feature, not a bug. An Oxford genetic study found that amphibian mitochondrial protein-coding genes evolve 3–22 times faster than human nuclear markers (source). With 40-50x shorter lifetimes, that is ~1000x human genetic variance. This was nearly the quickest mutation rate among all taxa, beaten only by land-based snails (mollusks). In other words, the two most threatened groups by extinction are also the fastest evolving.

This may be why amphibians have survived four prior mass extinctions while almost all other species have not. The meteor that killed off the dinosaurs 66 million years ago is estimated to have been equivalent to 10 billion atomic bombs going off simultaneously. A dinosaur in Alberta, Canada, would have had approx. two minutes from the time of impact on the Yucatan peninsula before being vaporized… Amphibians survived the fallout in a broiled atmosphere of deoxygenated air and highly acidified water, without direct sunlight, for thousands of years. While climate change is a severe threat, it doesn't hold a candle to that.

Heightened genetic adaptation is the hallmark of amphibians. The reptiles wiped out by that meteor had themselves evolved from amphibians. And hundreds of millions of years before that, amphibians’ made the most significant evolutionary leap ever to occur on planet earth. They brought complex lifeforms from oceans onto land. Imagine the acute evolutionary pressures in that transition… It’s astounding.

In the case of Chytridiomycosis, which was first observed in the 90s, we have the most deadly fungal outbreak ever recorded among vertebrates. And even nominal population bases of rainforest amphibians are showing signs of genetic adaptations within a dozen or so generations. That is lightning fast and certainly lends credence to optimism and hope. 

But what about habitat loss?

Habitat Layering: A New Perspective

Habitat loss creates winners and losers. Per studies on frogs, habitat losses demonstrated population losses among some species of 22x and gains among others of 37x (source). That's a significant divergence. 

While the losses may be easy to comprehend, the gains are worth considering. The key idea is habitat layering. It's not the case that nature is static, and humans destroy more and more of it over time in a cosmic race to annihilation. Instead, humans are modifying the land and adding new layers of habitat, such as rice paddies, cow pastures, rural, peri-urban, and urban. Different species thrive in different habitats (even urban), and, on the whole, the more habitats that exist within a large geography (including natural habitats), the greater the overall species richness. Here is an impressive meta-review of the subject, showing that biodiversity increased due to human-modified land across 95% of all studies (source). Diversity area relationships, or DAR, have increasingly been used as a replacement for SAR (source).

In a meta-analysis of 1148 data points from 192 studies worldwide, we find that separate effects of heterogeneity in land cover, vegetation, climate, soil and topography are significantly positive, with vegetation and topographic heterogeneity showing particularly strong associations with species richness.

The takeaway here is not that humans can continue to destroy the earth without cause or concern. That is not the message. Instead, this layered habitat logic reveals that humans can co-exist alongside nature, and if done in balance, biodiversity will increase. Increased species richness leads to new species over time. We can speed up speciation and protect endangered species if we carve out enough natural habitat to keep it balanced. What is the correct ratio? Estimates suggest that 10%-30% of the land remains unmodified by humans. This is the Teddy Rosevelt National Park & protected lands model of the United States. If layered habit logic had been integrated into Brazil’s coastal development plans, perhaps a larger percentage of the Atlantic forest mentioned above would have been saved, and with it a large share of the world’s endangered species.

Immigration increases diversity

Contrary to the notion that we live in a period of mass extinction, the total biodiversity of life on earth seems to increase exponentially. This remarkable observation goes back 500 million years to the first eukaryotic organism. Extinction events pull back biodiversity but also speed up speciation in their wake. One step back and two steps forward. While some argue that is precisely what is happening now: that we are both causing mass extinction and boosting speciation rates simultaneously, the data doesn't support that view. Extinctions over the past 500 years, at between 0.05% - 0.001% of life on earth, don't rise to mass extinction. More accurately, we have substantially reduced the stock of many species, while substantially increasing the stock of many others.

What to make of this? It's not to say that species are not going extinct. They are, and they will. We, as humans, are acting as an accelerant of evolution. We are catalyzing losses at a faster rate than ever before, but we are also catalyzing gains. And the net change is positive on any regional scale.

Almost all popular media focuses on losses while ignoring gains. Multi-lateral institutions, academic researchers, and NGOs all do it. While an understandable impulse, this would be like studying demographics and never looking at births. It has painted a stilted picture.

We live in a world of immense and accelerating change, of which there are biological gains and losses. Nature is a dynamic thing of gains and losses. It’s always been the case. We shouldn’t think of nature as some baseline state that we have to restore it too. No change is not an option on the table. It never actually was. Even the word conservation, from the route of ‘conserve,’ implies keeping everything the same. In light of this insight, we must rethink what conservation means: Professor Chris D Thomas, author of Inheritors of the Earth.

In terms of gains, we have brought everything, everywhere, over the blink of an eye in a geologic timeframe. We call these gains invasive species. They undergo rapid Darwinian divergence in new places and speciation with 'native species.' We're short-cutting a 100 million-year timeline for the continents to reconnect and for species to intermingle. Ocean-going container ships move species 10 billion times faster than migrating continents and airplanes 200 billion times more quickly. Darwin's Galapagos is now the archipelago of the entire earth. This is the new Pangea. Darwinian forces are in overdrive mode. 

If you want to read an entire book of examples on recent speciation, I highly recommend Professor Thomas's book Inheritors of the Earth. Stewart Brand, the famed environmentalist who created the Whole Earth Catalogue and successfully lobbied NASA to take the first image of earth from space, suggests that Thomas's book is the closest we have to ground ecological truth since Darwin's on The Origin of Species. That statement compelled me to read it and provoked me to write this article.

Here is a meta-analysis to demonstrate the invasive species biodiversity point. Professor Thomas presented the data below at the Long Now Foundation — Stewart Brand's think tank. 

The charts show the number of species in a given geography as counted now and as counted before human contact. The diagonal line is a one-to-one line, so if there are more species now, the dots will be above the bar. The studies would be below the line if more species existed before human contact. In all studies, the results are above the line. Most remarkably, for islands, the chart is on a logarithmic scale. So there are more species on islands now than before human contact. Often twice the biodiversity quotient.

Conclusion

While alarmism can be a useful tool to prompt action, it should not lead to overwhelming despair. It is crucial to base the alarm on accurate data. The political dimensions of this problem are real. Many form their identities around a view of environmental despair. Their community, their values, and their politics. All become an extension of that view. But if biodiversity is increasing rather than decreasing, if a richer fabric of genes are emerging through evolutionary forces, what does that do to the narrative? It doesn't ignore that climate change is a real threat to civilization. It doesn't bring back species that have gone extinct. But it does pose a radically different view of humans as an accelerant to evolution, instigating both gains and losses. 

Judeo-Christian beliefs are a core lead-in to the identity complex here. God created 'Man' in his image, and 'he' has dominion over the world… e.g., Humans are above nature rather than a part of it. In this view, nature is static, subservient, and open to exploitation rather than a dynamic and resilient system. A popular modern variant to the age-old story is that technological progress will soon crescendo into our own annihilation. I would argue that the 6th extinction narrative cleanly fits here too. Upon re-reading Elizabeth Kolbert's book, The 6th Extinction, I was struck by how heavily she relies on biblical language and parables as heuristics for her thesis. Apocalyptic storytelling has gone hand-in-hand with Judeo-Christian views throughout time. 

While there is much more to explore, this article has become quite long in the tooth, much like wooly mammoths soon to be brought back from the dead. Perhaps a deep dive into the promise of genetic engineering and species conservation is in order. I look forward to writing more on these subjects and others. More to come. If you enjoyed this, please subscribe. Gaining some traction out the gate here, on my first sub-stack, would be a real boon to continuing this style of content creation.