Speciesism, Science, and Society

Abstract

Speciesism is to species as racism is to race. The tenets of both are baseless on all grounds. Although our consciousness is currently raised toward the latter, the former remains persistent and infectious. Speciesism begins with how we view ourselves in relation to the natural world, and leads to behavior that challenges our future on this planet. Our naïve exceptionalism has repercussions for ecology, ethics, conservation, law, culture, and the energy and resource base that powers human society. We are merely a part of the natural world, though we have behaved for centuries through a myopia of perceived dominion. By our actions, we are now pushing against a significant number of planetary boundaries, such as threats to natural resources, climate, biodiversity, and the ecological networks that keep humanity afloat. With each passing day, the distinction blurs between the anthroposphere and the ecosphere, between humanity and the earth-system. As transformers of this planet’s environment, we are one of the greatest ecosystem engineers the earth has ever seen. Yet we remain dependent upon nature, and how we behave over the next few decades will determine our prosperity on this planet and beyond.

1 What is Speciesism?

Academics and the general public largely remain unaware of the concept of speciesism (Jones 2020; Gunderman and White 2021). There certainly exists a familiarity with ethical issues such as factory farming, clearcutting forests, or overfishing. Yet confusion remains about speciesism itself, its underpinnings, and its extensions which transcend the history and future of life on Earth (Fjellstrom 2002; Bindig 2007; Horta 2010; Jaquet 2019). It is the purpose of this chapter, and this book as a whole, to expand this discussion and lay a foundation for what emerges from how we view ourselves in relation to the natural world.

If human behavior is our guide, it is clear that we view ourselves as undeniably superior to other living things. The problem is that most people do not realize they have this view, and thus can’t easily see the effects that extend into other facets of the human experience (Wilson 2012). Wherever you look in human behavior, speciesism is likely found. It may start with an Instagram post with a person standing on wildflowers thus damaging the very thing they signal to care for. Yet speciesist views extend to a diverse set of topics including: the religious influences that have shaped our self-concepts and global actions; how we treat ecosystems and other organisms; how we grow food and manage the consequences of its production; and how we procure non-living natural resources such as energy that we need to thrive.

While speciesism begins with a selfish notion of perceived human specialness, it extends afield into the future of our existence in the tree of life. We are one lineage (see the definition of this and other terms in Table 1.1) that is genealogically related to millions of other lineages—all living things. Our ancestry has its roots in an extensive genealogy that has been branching and reticulating (merging) for about four billion years. We also share a global environment with all living things. We are related to, and connected with, the rest of life, and our actions both affect and depend upon our relatives.

Table 1.1 A glossary of commonly-used concepts throughout this book

1.1 Speciesism: Evolutionary and Ecological Thinking

It is helpful to consider “tree thinking” when visualizing humanity’s relationship to other forms of life. This heuristic mindset derives from methods that biologists use to reconstruct the evolutionary relationships among organisms (Baum et al. 2005; Gregory 2008). The branching diagrams that result are called “phylogenies” or “evolutionary trees” (see Fig. 1.1). When we hear about the tree of life—or a lineage, a branch on the tree of life—it is in reference to these kinds of diagrams. “Tree thinking” is about understanding how these diagrams communicate information.

Fig. 1.1

An evolutionary tree showing the relationships among you and your nearest relatives. We do not read across the tips of branches (living descendants) to understand ancestor–descendant relationships. You did not give rise to your sibling nor did you come from your second cousin. You are all descendants of shared common ancestors. A “lineage” refers to these ancestor–descendant pairs. For simplicity, many branches have been excluded that would fall between humans and the other primates depicted

There are specific ways to read, understand, and decipher a phylogeny. For example, in Fig. 1.1, although it is intuitive to read across the tips of the branches, this would lead you to misunderstand what is being conveyed. The tips of each branch refer to living descendants of ancestor–descendant pairs. The diagram does not signal who is ancestral to whom, but rather how recently two tips shared a common ancestor. The depth of a shared branch indicates this. For example, you are a descendant of ancestors with a deep familial history. Your siblings and cousins are also a product of this history. Yet no one would argue that you gave rise to your aunt or that your sister came from your brother. Instead, it is a point about recency of common ancestry. You share common ancestors with your siblings (parents), just as you share common ancestors with your aunt (grandparents). These same concepts apply throughout the tree of life.

For example, reflecting on the attributes that make you unique—from personality traits to the genetic/environmental influences that shaped you—there is no other person on Earth who can fill your shoes. Comparatively, each branch on the tree of life is also unique. We all have combinations of features that make us special, and no lineage is evolutionarily “higher” or “lower” than any other.

Whereas it may seem true that humanity dominates the planet at a scale not seen by other organisms, the earth has been and likely forever will be dominated by microbes (Gould 1996) (see Fig. 1.2). The tools we use to manipulate nature circle back to remind us how much we remain a part of this microbial world. For example, despite our cleverness, we are running out of antibiotics (Stadler and Dersch 2016). This predicament partly stems from industrial farm animals spending their entire lives on rigorous antibiotic regimes (Anomaly 2015). We are a tiny branch on the vast tree of life, and share with millions of other branches a network of dependent interactions. Humanity takes massive risks when we fail to consider our modest place in relation to the rest of nature.

Fig. 1.2

The tree of life, modified from Hug et al. (2016) and Burki et al. (2020). There are two primary branches, Bacteria and Archaea. Escherichia coli are a common example of bacteria (in our GI tract). Methanogens are an example of archaeans (in the guts of cows) who produce methane from their GI tracts. Interestingly, as archaeans, humans are more closely related to methanogens than we are related to the E. coli in our own guts. Eukaryotes (in green) are Archaea that include organisms like ourselves with a nucleus in their cells (e.g., ALL other animals, plants, fungi, etc.)

1.2 The Scientific Problems with Speciesism

Speciesism carries two fundamental precepts: (1) species are real; (2) one or more of these species are superior to others. The speciesist embraces both propositions. However, the picture is nuanced and concepts are nested. For example, “species realism” is the view that species are uniquely real (Mishler 2010, 2021; Mishler and Wilkins 2018), while “speciesism” pairs species realism with an argument for superiority (see Fig. 1.3).

Fig. 1.3

The conceptual relationship between species realism and speciesism

To understand this, it can be helpful to draw an analogy to racism. Racism also carries two precepts: (1) races are real; (2) one or more of these races are superior to others. Like speciesism, embracing superiority encompasses the view that races are privileged categories. The parallel does not stop there. Like “species realism,” “racialism” views races as biological entities (i.e., as more than cultural constructs; Appiah 1989). One can be a racialist without being a racist as one can be a species realist without being a speciesist. However, the problem with speciesism and racism is that they are both scientifically baseless. But how so?

Consider speciesism in parts: (1) species are uniquely real; (2) at least one species is superior. See Sect. 1.4.1 below for details concerning species concepts in biology. For our purposes here, it suffices to say that whether we focus on sex, anatomy, ecological differences, or phylogeny, no species concept consistently and accurately describes life as it exists across the tree of life (Mishler 2021). It is because of this diversity that we have so many species concepts. The things called species are not uniquely real.

Curiously, we can still recognize real biological “things” across the tree of life. These “things” are lineages and clades, based on ancestor–descendant relationships that on occasion split into separate streams (Mishler and Wilkins 2018). See Table 1.1 and Fig. 1.4 for the distinction between the related but different terms “lineage” and “clade.” Ancestor–descendant relationships can be short like those shared between you and your parents or go deep into the past. Sometimes lineages split, other times they merge, and other times they go extinct, but they all together make up the tree of life.

Fig. 1.4

An evolutionary tree showing the relationships among a subset of plants and animals. “Lineages” of plants are illustrated with a black core and green outline, here specifying the branches that connect the common ancestor of plants to its living descendants. A “clade” is a cross-section (x.s.) of these lineages at any level. For simplicity, many branches have been excluded that would fall between those depicted here

Fig. 1.5

This is the relationship between branches on the tree of life (colored lineages) and the taxonomic levels in the hierarchy (black lines) that humans have used to classify life. Lineages split and merge as they originate and go extinct. These lineages are real biological relationships that connect living things in nested groups. In comparison, taxonomic ranks (e.g., species, genus, etc.) are human constructs that are neither real nor equivalent across groups. The species level is no more special than the genus, family, phylum, or kingdom level. They are all arbitrary cut-offs along a continuum with no privileged position (colored background tree drawn by Karen Klitz)

Species realism begins to fail when humans impose taxonomic ranks onto the natural world. For example, a “species” of mammal, a “species” of plant, and a “species” of fungus are not the same thing. Comparatively, the species level is not different from any other taxonomic rank in that every level in the hierarchy is an arbitrary boundary that cuts across the tree of life at variable depths (Mishler 2021) (see Fig. 1.5). In contrast to species, lineages and clades carry the same meaning in all groups of organisms. Importantly, lineages allow us to measure the earth’s biodiversity with precision without ranks, using a measure called “phylogenetic diversity” (Faith 1992; Mishler et al. 2014; Thornhill et al. 2016, 2017; Chap. 8 in this book).

Knowing that lineages make up biodiversity reveals a second issue: the tree of life is fractal. Biodiversity is about branches, from parents and offspring to deep common ancestry. An arbitrary species-level-cut exists across the tree and the depth of this cut varies among groups. This reveals that the species level is not exceptional among a continuum of lineages, bigger or smaller, and that all are important to consider for various purposes including conservation (Mishler and Baldwin 2021).

The arbitrary nature of the species level affects attitudes towards speciesism, of course. One construct cannot be superior to another construct if they are non-corresponding arbitrary entities. If the speciesist proposes the unique reality of species AND embraces superiority then both tenets fall flat. Lineages make up the tree of life and all extant tips of this tree are equally present today, with none higher, lower, or ethically superior.

Considering this, let us extend the parallel between species and race. Human races are not distinct branches (lineages) within humans; they are cultural constructs (Templeton 1998, 2013). Members of one so-called “race” are not always closely related. For example, one might look “Caucasian” but be more closely related to a Moroccan cousin than those cousins are related to fellow Africans in Nigeria. Races cannot be superior to others if they do not exist as biological categories. A socially constructed group may better at doing a particular thing, but that doesn’t mean there is an underlying biological “race” that unites them. Behaviorally, this matters because how we see ourselves influences how we treat other people (racism) and how we treat other living things (speciesism).

One lineage may be empirically superior to other lineages in a specific functional trait, of course (e.g., eagles have better eyesight than humans). Yet it is essential to remember that adaptations (see Table 1.1) are about the relationship between an organism’s traits and its environment (Darwin 1859). Adaptation is not universal across all traits, and there are constraints imposed by developmental relationships among traits. Humans have a mixture of traits like all other organisms, some “good” traits and some “bad” (Gould and Lewontin 1979). We may be unable to fly like bats or swim like whales, but we have a gift of foresight and planning. We are working hard to promote sustainability and venture afield on an interplanetary scale. However, aspects of our intelligence may be maladaptive in the arc of humanity’s future. We are capable of some of the most astonishing accomplishments, but as emotional animals, our minds often hijack themselves (Asma and Gabriel 2019). What the future holds within our prevailing environment is an experiment in progress.

Until then, we must be keenly aware of speciesism during this time of perceived dominion. Human beings are probably the most dominant ecosystem engineers the earth has ever seen. However, we are also the worst “weed” the world has had to deal with. Over the last few hundred years, virtually no part of this planet has gone untouched. Whether we consider the energy and resources that fuel civilization or the larger earth-system that we expand into, the effects of our behavior are profound (Rockström et al. 2009; Hughes et al. 2013; O’Neill et al. 2018). Why do we behave as we do? Why do we assume that we have the right to modify the planet as we wish and subjugate other living things to our needs? We often overlook intrinsic values in organisms and natural resources (“intrinsic” as in something special about an entity in question) and instead pursue instrumental values (values that relate solely to our benefit) (Moffett 2020). Our unquestioning attitudes about dominion over the rest of nature are strikingly similar to the unquestioning attitudes held by dominant cultures throughout history about their dominion over the rest of humanity.

There is little doubt that we love ourselves to the exclusion of others. Perhaps this is understandable as a form of “us versus them” thinking that derives from our evolutionary past. But these tendencies cost us tremendously within the modern world (e.g., race, religion, politics) and across the tree of life (e.g., extinctions, loss of ecosystems, global climate change). As a civilization, we do not hide, or even realize the depths of our perceived superiority. We view ourselves as “better” than the rest of life.

Human actions indeed reveal deep seated speciesism. Grounding us in the natural world is probably the first best step toward dethroning our misguided exceptionalism. For millennia, we have constructed ideas and belief systems that position us at the “top” of life on Earth (Lovejoy 1963). These beliefs have placed Homo sapiens (wise man) as THE animal to “fill the earth and subdue it,” to “have dominion over the fish of the sea and…over every living thing” (Genesis 1:28). We have done precisely this. For years, humans have debated what makes us special, be it language, tool use, culture, consciousness—all shades in a continuum with parallels and antecedents in other organisms (Lieberman 2013; Bickerton 2014; Tomasello 2014). However, there is one distinguishing point that makes the case for itself: we are likely the only organism, ever, that has spent mental effort trying to convince itself of just how exceptional it is.

2 A Sawyer Seminar Funded by the Andrew W. Mellon Foundation

This volume stems from a seminar series on speciesism held in 2012–2013 at the University of California, Berkeley, funded by the A.W. Mellon Foundation. This book follows the same format as the original seminar series by viewing speciesism in light of biology, culture, history, conservation, law, and sustainability. We have kept many of the same topics, though we have added new topics in the spirit of our times (e.g., the social concept of race, pandemic diseases, and the future of food and energy). Some of the seminar speakers contributed chapters to this book, and we invited additional scholars to contribute.

We first unpack speciesism by rooting humanity within the tree of life. Doing this allows us to see the evolutionary and ecological themes that connect our lineage with the rest of life. We expand this by revisiting early human civilizations to understand how smaller societies behaved on islands as humanity now acts globally. Throughout human history, islands have been microcosms of present impacts. This dissection of a “historical small” within a “current big” makes human actions tangible and clarifies how we repeat old behaviors. Will we continue these antics as we pursue interplanetary travel and treat planets as new microcosms within the universe? What insights exist in this landscape of past mistakes and future visions?

We then look into how humans are treating the current world. What does human behavior say about how we value forest resources (FAO 2020a), ocean resources (FAO 2020b), and the free services (e.g., pollination, photosynthesis, air to breathe, climate regulation, etc.) that come when these environments are intact (FAO 2020c)? How are we treating domesticated plants and animals, including soils that these organisms grow in or live upon? How do our cultural systems (e.g., religious, industrial, political, legal, medical) align with and extend from human-environment interactions? What do our cultural systems reveal about what we value? In medicine, if our microbiome (the totality of microorganisms that live in and on us) slightly outnumbers our cells by a ratio of about 1.3:1, then what does this say about what it means to be human, yet alone a “species?”

In the current landscape of pandemics and zoonotic diseases (diseases transferred between human and non-human animals), how is our perceived exceptionalism accelerating global problems? As the human population grows and we consume more resources, city centers become more dense. How will this affect our management of contagious diseases? How will we feed this world? How will energy power this future? Like any complex open system, human civilization requires energy. As we strive to wean ourselves off fossil fuels, what clean and sustainable alternatives will power a society that remains dependent upon the laws of physics? These are all questions that inevitably flow from understanding speciesism and its consequences.

3 Major Topics Related to Speciesism Covered in This Book

The chapters in this book follow the arc of the original seminar series, although with expanded breadth. Major themes include alignments between speciesism and racism; connections to ecology and evolution; behavioral antecedents in human pre-history; the influence of religion on human perception in relation to nature; the role of symbols as social meanings in humans and other animals; current ethical and legal manifestations as an extension of human behavior; the affects of speciesism in conservation biology; and the civilizational consequences of human actions on interplanetary scales. In this section we give short summaries of the other chapters in the book. In the following Sect. 1.4 we discuss a few additional topics that are not represented by separate chapters in the book.

3.1 Race and Human Genomic Variation, Rasmus Winther

In his chapter, Winther shows that we differ genetically far less than intuitions suggest. Compared to our differences with close relatives, there is relatively little genomic variation within Homo sapiens. Among the 3 billion base pairs (DNA letters) that compose our genomes (one from each parent), they are 99.9% identical among all humans. Interestingly, African genomic variation is the richest and most distinctive among all continents. Further, this pattern continually decreases as geographic distance from Africa increases; we vary less as we move away from Africa. In essence, we are all Africans, despite superficial differences in appearance or skin pigmentation.

Winther invites us to see that surface-level variants should not matter ethically or politically. If we differ by only 0.1% at most, with most differences in Africa itself, what does this say about the biological core of humanity? We are fundamentally the same. What does this imply about the basis of racism? It is empirically unfounded.

How can we pull from this insight to rally around a unified cause, a shared vision for a shared future, as members of a single lineage (Homo sapiens) trying to manage its existence on a finite planet? This question is more complicated, yet if we can embrace our homogeneity and act, then perhaps we can start behaving as though our future depends upon it. How we treat the world and each other affects all that we engage with, especially when our actions affect prosperity.

3.2 Science Without Species, Nicholas J. Matzke

In recent decades evolutionary biology has begun to move away from species as the key unit of analysis to address biological questions. In this chapter, Matzke begins by outlining how phylogenetic comparative methods have become essential tools in statistical analyses of trait relationships. Species are not statistically independent observations because they are related to different degrees on a phylogenetic tree. In fact, moving to a phylogenetic view of biodiversity can avoid a number of problems created by attempting to impose a uniform species rank across different geographic regions and clades. A major challenge in modern studies of diversification and extinction is the units of analysis and how they are defined and recognized. Taxonomic ranks including “genus” and “species” are human-defined levels imposed on a phylogenetic tree. The tree itself is the reality produced by the macroevolutionary process, and it includes every level of gradation in evolutionary divergence. Once ranks are imposed upon it, a variety of methodological problems are created as scientists compare ranks across datasets and timescales. Phylogenetic thinking can provide a solution. Matzke concludes this chapter with examples where cutting-edge science is done without need of the “species” rank.

3.3 Islands as Microcosms of Human Impact, Scott M. Fitzpatrick

The colonization of islands by humans in the ancient past provides study systems for human impacts on a manageable scale. In this chapter, Fitzpatrick initially focuses on the vast expanse of the Pacific, where beginning ca. 3000 years ago, Micronesian and Polynesian voyagers colonized the most remote, and final places to be reached by humans. The biota of these islands evolved independently for thousands or even millions of years, resulting in high rates of endemism and extremely fragile ecologies. The first arrival of Homo sapiens caused a wide variety of impacts that were greatly amplified later with Euro-American incursion. As ecologically bounded places, islands thus serve as model systems for how humans affect the earth’s biosphere in the modern age.

Fitzpatrick takes this concept further, suggesting that the processes involved in the prehistoric colonization of islands are a corollary for current global impacts and extraplanetary colonization. As the possibility of extraplanetary migration becomes a reality—perhaps even a necessity to ensure our survival—Fitzpatrick invites us to ask what lessons we can learn from the archaeological study of islands. What are the consequences for us and for other forms of life on this planet and possibly others? Will we learn from our mistakes or will we bring them with us? The earth is only one of many habitable islands in the larger cosmos. How will we manage the present manifestations of human behavior, growth, sustainability, economics, ethics, disease, density, and the future of food and energy?

3.4 Species, God, and Dominion, John S. Wilkins

In this chapter, Wilkins argues that having a “theoretical” notion of species causes harm to science and polity. He clarifies that species as a concept is the result of theological and philosophical considerations, with deep historical roots, not any current empirical or scientific need. Yet the idea of biodiversity existing as bounded species units still holds political importance for religious ideas of dominionism, or supposed human supremacy over nature. It also carries tremendous impact on environmentalist and conservationist politics in the United States and elsewhere. Fundamentally, as Wilkins explains, the current concept of species is damaging since it retains much of its essentialist religious origins and emphasizes human exceptionalism to the detriment of expanding our attitudes about the rest of life.

3.5 Symbols and How We Came to Be Human, Mark W. Moffett

A major belief behind the idea of human exceptionalism is that Homo sapiens is distinct from other taxa in our use of symbols. In this chapter, Moffett considers the concept of “symbols” to describe anything with a socially shared meaning but without obvious ecological utility. Countering the argument that symbols are unique to humans, Moffett proposes that they be recognized as agents in other animals that operate in a diversity of ecologically meaningless “social markers.” For example, broadly speaking, social markers might signal ingroup versus outgroup identity, and manifest in ways similar to how humans posture as they walk, express emotions, or use scents or cultural ornaments to decorate their bodies.

What does the broad tendency for “marking” traits suggest about the evolutionary origins of symbolism? Moffett critiques views of human symbolism expressed by sociologists, psychologists, anthropologists, archaeologists, and biologists. Instead, he proposes that symbolism might have arisen from behaviors in other animals which live in societies bound together by simpler “markers” of identity, such a group scents or vocalizations that do not convey ecological significance. Importantly, such markers can be essential for holding societies together.

3.6 Human, Non-Human, and Ecosystem Rights, Gary Steiner and Marc Lucht

Western philosophical tradition has long maintained that only humans can possess rights. In this view, attributing rights to non-human animals is dubious and attributing rights to the non-sentient natural world in nonsensical. However, in their chapter, Steiner and Lucht analyze the commitments motivating this conception of rights and reveal that it is based on self-centered prejudices of humans that their own type of sentience is required for full moral status. Steiner and Lucht show how recent research has elucidated the intellectual and emotional lives of other animals, making it necessary to rethink their moral status. More radically, they show how rejecting anthropocentrism opens the door to recognizing that certain non-living entities also deserve moral consideration and have rights to respect. The differences between the traditional and the new approach to rights draws into question the conditions for moral worth and highlights our need for a satisfactory theory of the world and understanding of the proper place for humanity within it.

3.7 A Phylogenetic Approach to Conservation: Michael F. Allen and Brent D. Mishler

As late as the sixteenth century, the world was a matrix of wild lands. Due to rapidly increasing technological development and population growth, we increasingly subjugated and diminished the natural world. By the eighteenth and nineteenth centuries, some pushback occurred, with calls emerging for conservation. National parks were established and laws passed that were designed to save endangered species. In this chapter, Allen and Mishler show that while the “one species at a time” approach can be credited with saving many individual taxa, it is insufficient to deal with the current biodiversity crisis given urgent pressures on remaining natural lands. They advocate moving from a “single-species approach” to an “area-based approach” that incorporates a broad phylogenetic definition of biodiversity. Biodiversity conservation should not focus on the arbitrary level at which species are named. Instead, it should be focused on the whole tree of life. Allen and Mishler discuss new spatial phylogenetic tools that leverage recently available DNA and geographic data, plus new computational tools, to incorporate all levels in the tree of life when making conservation decisions. To protect biodiversity amid increasing environmental impacts, we need to adopt cutting edge strategies for conservation to allow life to thrive and ecosystems to function.

3.8 Energy and Society: Toward a Sustainable Future, Saul Griffith

Energy is the single greatest lever that moves civilization. As a society, we have pulled upon fossil fuels as a historical source of energy, but have begun transitioning toward alternatives. In this chapter, Griffith explores our global move toward alternative energy, its feasibility and impacts, and the kind of world we can create with a decarbonized and electrified future. He considers how much energy we actually need, and evaluates alternative sources of energy including nuclear power. Then he examines what the effects of achieving a sustainable energy future would be, including impacts on biodiversity and land use. Throughout the chapter, Griffith explores how to achieve sustainability while avoiding destruction of the rest of biodiversity and positively uplifting humanity.

4 Other Topics Related to Speciesism

Speciesism connects to a variety of other subjects that we were not able to include as chapters in the book. Thus, we give an encapsulated treatment below of the nature of biodiversity, human population, health, medicine, and the integrative future of food.

4.1 Species, the Arbitrary Constructs of Biodiversity

It was Darwin (1859) who first realized that the species level is not unique. As he saw it, lineages diverge for various reasons, though at some point (out of convenience), a taxonomist decides to call a lineage a species even though nothing fundamental happened at that point in divergence. By the early-mid twentieth century, evolutionary biologists such as Theodosius Dobzhansky and Ernst Mayr reintroduced species as a “unique” level (Dobzhansky 1937; Mayr 1982). They used their “Biological Species Concept” (BSC), proposing that interbreeding is the key criterion that happens uniquely within species (see Mishler 2010 for detailed discussion).

However, the recent availability of extensive genetic data within and between named species makes it abundantly clear that Darwin was right and the BSC does not apply in plants, animals, or microbes. Interbreeding and other forms of horizontal gene transfer (i.e., genetic exchange across lineages, distinct from the normal vertical transmission between ancestors and descendants) happens at multiple hierarchical levels across all life (Husnik et al. 2021). Contrariwise, there is a lack of interbreeding at many levels as well (Mishler and Donoghue 1982). There is no magical “species level” where rampant interbreeding abruptly transitions to no interbreeding. Instead, there are nested clades that are smaller and larger than the traditional species level that play essential roles in ecology and evolution.

In other words, the situation is richer and more interesting than the BSC took into account. A multi-level approach is a more accurate way to study the origin, maintenance, and conservation of biodiversity (Mishler 2021). A similar suite of processes act at various levels in the tree of life, albeit with a balance that shifts in exciting ways at various levels in different parts of the tree. A revolution in many areas of study (e.g., diversification, niche evolution, biogeography, coevolution, and conservation) will follow once a multi-level view replaces a rigid focus on the species level or other taxonomic ranks (Mishler 2022).

Granted, present methods based on taxonomic ranks do provide a rough estimate of diversity over time. In paleobiology for example, ranks provide utility since they allow discovery of patterns and processes that regulate global biodiversity (Sepkoski et al. 1981; Alroy et al. 2008, Barnosky et al. 2010). Current methods enable practitioners to reveal major historical events even if the ranks are arbitrary. For example, there have been five mass extinctions over the last 541 million years (e.g., via extraterrestrial impacts, widespread volcanic eruptions, climatic events that followed, sea-level changes, etc.). We can discover how environments and taxonomic groups were affected by these global changes. There has been fruitful research in this space, even as it aligns with the sixth mass extinction of the present day (Barnosky et al. 2010). In context, ranks represent diversity at some level and carry some utility when insufficient data make it hard to resolve phylogenetic relationships. This does not mean that ranks are natural categories, though they do allow us to roughly estimate biodiversity in the fossil record.

However, to measure diversity with the greatest precision, “systematics” (the discipline for classifying life) needs to move towards naming only clades, while eliminating ranks, including species. Much progress has been made towards that goal. The newly published PhyloCode (Cantino and de Queiroz 2020) is a major step in that direction, but it is still not logically complete since the species rank remains embedded within it. The community of PhyloCode supporters is split on this (Cellinese, Baum, & Mishler 2012), and it will be interesting to see if the PhyloCode can further evolve to become completely rankless as advocated by Mishler and Wilkins (2018).

Whether the species rank is formally eliminated or not, it is important to understand that the species level is arbitrary and that different entities called species have nothing necessarily in common. Instead of viewing biodiversity as “the set of species on Earth,” we should view biodiversity as “the entire tree of life,” with branches at many different levels having interest and import. Humans are literally related to all other living things, which should affect our ethics and inform how we treat them. The sooner we can wrap our minds around this truth, the sooner we can understand the concepts and processes at play. This realization allows us to see what speciesism means and how it weaves into the biological and cultural manifestations that emerge from it.

4.2 Human Population

About 300,000 years ago, Homo sapiens split from other branches of the Homo lineage (Hublin et al. 2017). Yet our origin did not proceed without extensive interbreeding (reticulation) with Neanderthals as far back as 100,000 years ago (Bergström et al. 2021). It took every year of these 300,000 for the human population to reach one billion. That happened in the year 1800. Since then, our population has grown exponentially, reaching two billion (1927), three billion (1960), four billion (1974), five billion (1987), and today (2022) has just passed eight billion. Growth rates have slowed despite the ongoing upward trajectory (Vollset et al. 2020), but many challenges have surfaced as the human population has swelled (Bradshaw et al. 2021).

The current balance between birth and death rates explains population growth rate. However, this is not the full story about environmental impacts since per capita consumption varies widely. In developing countries, birth and death rates are often higher than in developed countries, but citizens of the developed world consume many more resources on average (UNDP 2020). The balance between reproduction and consumption provides insights into our resource footprint and the number of people the earth can sustain (carrying capacity). Data suggest that we currently consume resources as if we lived on ~1.75 Earths (Global Footprint Network 2020), even though there is only… one. The earth’s carrying capacity for humans is not well understood (Cohen 1995). Most published estimates suggest that it is between 8 and 16 billion (Pengra 2012). However, we have changed our carrying capacity multiple times throughout history (Goudie 2019). Since at least the industrial revolution, we consumed energy and natural resources to fuel a growing civilization (Crutzen 2002; Crutzen and Steffen 2003; Hoekstra and Wiedmann 2014). Current growth and consumption rates are unsustainable, but where are the limits and how are the resource inputs changing? This partly depends on what standard of living is acceptable and on the accelerating rate of technological change. Is the goal to keep people alive, or some higher standard that includes space, amenities, and opportunities for humanity and the rest of biodiversity?

One challenge is that even though developing countries have higher birth rates, the impact of each person on the environment is much greater in developed countries (UNEP and IRP 2011; Kampang and Shaoqi 2012). In part, this is why sustainable economic growth is key to many aspects of human wellbeing. If population growth outpaces economic growth, the consequence is slum-like environments where essential services are sacrificed, such as sanitation, law, medical care, clean water, etc. (Oof and Phua 2007). These environments become grounds for poverty, disease, and suffering (Marmot et al. 2008). This is a tremendous reason to support developing countries, to keep their economies sustainable, their environments intact, and to reduce birth rates while increasing prosperity. Much about human health is intimately connected to the economic, environmental, policy, and values-based decisions that accompany a growing civilization (FAO 2020d; Vollset et al. 2020).

Thus, we have many goals for the pivotal year of 2050. These include transitioning to alternative forms of energy, managing the global climate, conserving natural resources, combatting food security, leveraging exponential technologies, among countless others (Hubert et al. 2010; Griggs et al. 2013; Gates 2021). It is clear that one important way to improve prosperity is to give equal rights to women, enable their voice in decisions on family size, and provide education and healthcare to all. Around the world, data show that birth rates decrease as these resources are provided (United Nations 2017). Compassion is a precious thing, especially when the consumption of energy and natural resources has driven our economic path. We are victims of our success in many ways.

Even as birth rates decrease and societies transition demographically, greater affluence increases global consumption. Reproduction and consumption are thus interdependent, even in a sustainable world with a healthy human population and a diverse environment. By 2050, there will be about two billion more humans on Earth, for a total of about 10 billion. It will increasingly stress our infrastructure to sustain this civilization while managing the climatic, energetic, and environmental impacts that currently result from our “business as usual” path (Griggs et al. 2013; United Nations 2017).

This is one reason why it’s crucial to leverage information technology and to accelerate the rate of information that we discover and return to civilization (Kurzweil 2004, 2005). Artificial intelligence, machine learning, blockchain technology, materials science, and quantum computing are examples of such tools (Kissinger et al. 2021). The compounding rate of innovation can thus permit an abundant future by changing the inputs and outputs to engineer prosperity (Diamandis and Kotler 2012, 2015, 2020; Bastani 2019). In contrast to the pace of government and policy decisions, significantly moving this dial is about catalyzing human behavior change by applying current and new technologies for the human population at scale.

4.3 Public Health and Medical Implications

There are health consequences that connect to every aspect of population growth at this scale. Examples include: air pollution that results from the tools that power civilization (e.g., combusted byproducts of fossil fuels, airborne industrial and agricultural wastes); climate-related extreme weather events (e.g., floods, fires, hurricanes); vector-borne diseases that spread poleward from the tropics as climate belts shift (e.g., dengue fever, West Nile virus, Rift Valley Fever); environmental toxics that accumulate and magnify in regional environments and human bodies (e.g., endocrine disruptors, carcinogens, heavy metals); challenges growing food via traditional agriculture (e.g., the depletion of soil nutrients, plants living in environments they are not adapted to, the environmental and health impacts of agricultural techniques); and the stressful mental health issues that people face amidst these challenges (WHO 2021a). In a world where the biology of stress approximates the biology of western diseases (Sapolsky 2004, 2005), what looming public health crises exist over the horizon?

Late 2019 saw an unprecedented public health crisis: SARS-CoV-2, the virus that causes COVID-19 (coronavirus disease 2019). Research into the origin of this coronavirus is ongoing (Anderson et al. 2020; Rasmussen 2021; Sallard et al. 2021; Segreto and Deigin 2021; Segreto et al. 2021; Shi 2021). Whatever the origins turn out to be, one message is simple: human population densities are as critical to public and environmental health as is the total size of our population. Both have signals that underpin sustainability and wellbeing. Harvesting resources, including wildlife, as we encroach on natural habitats increases the likelihood of encountering zoonotic diseases (i.e., the transfer of disease agents to humans from other animals; Rulli et al. 2021). We also live in a connected world where humans move and where densities can be high. Pathogens function best in these environments. This is why “social distancing” reemerged as a phenomenon in 2019, to decrease population densities (e.g., “6 feet apart”) and lower transmission likelihood.

We are no longer hunter-gatherers in a low-density world. The anthroposphere (the ecological landscape we have created) provides new situations for opportunistic microorganisms. Human culture transforms ancestral environments and microbes take advantage of shifting landscapes. It is a case when worlds collide. Humans are spectacular ecosystem engineers but there are other players on this chessboard (Darwin 1859; Van Valen 1973). Moves are met with countermoves, even if we didn’t anticipate them. While we sink our wedge deeper into this landscape (acquiring resources while displacing others), microbial players discover our vulnerabilities. 2019 revealed that these opportunists can cause global pandemics, kill millions of people, and bring economies to near standstills.

It is striking to consider how viruses reproduce in the first place (V’kovski et al. 2021). They require host cells to replicate. They inject their DNA into the genome of a host, thereby hijacking its cellular machinery and instructing it to make viruses. This process doesn’t just allow viruses to reproduce. It also leaves behind a fraction of viral DNA. It is estimated that about 8% of the human genome is viral DNA (Belshaw et al. 2004; Jern and Coffin 2008). This genetic intermixing produces an outcome that can be compared to other ways that organisms reproduce. For example, animals primarily reproduce from sperm and egg. This means that DNA in the offspring comes from the merging of paternal and maternal sources. Sexual versus viral reproduction are obviously different, but the pattern is much the same: lineages coalesce and exchange DNA at various points across the tree of life.

The frequent merging of lineages over evolutionary time illustrates how erroneous it is to think that species are uniquely real units because DNA is only shared within the same species (Mayr 1982). Evolution is about lineages, forward to the present and back to the past. They split, they merge, they go extinct; tree thinking is core to understanding this. What value does focusing on the classical species level bring to considerations of reticulation and zoonotic diseases? None: it diverts our attention from grasping the processes at play, the levels involved, the patterns that emerge, and applying this knowledge to discover tools to manage pandemic diseases.

2019 exposed us to a new lineage of coronavirus that slowed humanity to a near standstill. Its genes merged with ours and killed over five million people in two years (WHO 2021b). A pandemic at this scale was predicted during the previous decade (Gates 2015). Let COVID remind us that we are neither superior to, nor separate from, the rest of life on Earth.

4.4 Food: Nutrition, Energy, Climate, and Biotechnology

The future of food is among the most integrative subjects of our time. It includes connections that weave through nearly every facet of the global environment, and speciesism resides at its core. How we see ourselves in relation to nature determines how we treat other organisms, how we view habitats that foods come from, the methods we use to capture or cultivate these foods, and the civilizational consequences of our actions. Food entwines subjects such as energy (Pimentel and Pimental 2007), climate (Rosenzweig et al. 2020), biodiversity (Worm et al. 2006; Crist et al. 2017), soil health (McBratney et al. 2014), ocean health (Halpern et al. 2015), biotechnology (Steinwand and Ronald 2020), nutrition (Domingo et al. 2021; Meyers et al. 2017), the future of contagious diseases (Rulli et al. 2021), and the ethics that guide human behavior in these spaces (Wilson 2012).

One of humanity’s grand challenges over the next 30 years will be growing food sustainably for a population of about 10 billion. The food system is a subset of human ecology, an economy of nature powered by energy. At present, fossil fuels provide most of the energy that drives food production and distribution (Shukla et al. 2019). Our food is either wild caught (e.g., fishes) or grown (e.g., agriculture or aquaculture). Amidst a more extensive energy transition, we are working to wean ourselves off fossil fuels and power all of civilization (including food) via sustainable alternatives. Yet in the meantime, about one-quarter of our carbon footprint comes from food production and how we use the land it grows upon (Ritchie and Roser 2020). Trying to feed everyone carries tremendous potential to impact the global climate and biodiversity. Presently, industrial agriculture functions ineffectively at mitigating the ethical, environmental, and public health effects of food production. This appears as deforestation, habitat loss, overfishing, monocultures, biocide and fertilizer overuse, nutrient runoff into coastal dead zones, desertification of farmed soils, depletion of soil nutrients, groundwater depletion, and the government subsidies that incentivize many of these methods (FAO 2020a, b, c, d, e). We can do better.

We are beginning to produce food using more healthy and sustainable tools. While the global energy landscape is transitioning toward alternatives, the food landscape is changing as well. Regenerative agriculture helps to mimic natural ecosystems (cycling nutrients back to their environments) while sequestering carbon from the atmosphere and giving healthy lives to farm animals that allow this to happen (Duncan 2016; Lal 2021). Hydroponics and aquaponics provide tools for growing plants indoors without abusing farmed soils with chemical fertilizers, groundwater depletion, and widespread biocide use. Healthy aquacultures are also becoming common, with algae at the base of their food systems in contrast to food pellets made from corn, soybeans, or reef fishes (Goddek et al. 2019). As a form of cellular agriculture, cultured meats are also growing (literally). We are discovering more effective ways to financially and energetically grow muscle cells to make cultured alternatives to what would otherwise emerge from a factory farm (Humbird 2020; Triech 2021). For the first time in history, cultured meats carry the potential to create food from plant and animal cells and to make many unethical practices of the modern industrial farm disappear.

Unfortunately, “ecological thinking” has challenged food production technologies since the Industrial Revolution. In modern forms, this might manifest as raising salmon or cows on a diet of corn. This diet increases the concentration of pro-inflammatory omega-6 fats because it skews the omega-3:6 ratio in their tissues (Simopoulos 2003). This happens because corn plants store omega-6 fats as energy for young seedlings, fueling their growth and the eventual synthesis of green photosynthetic leaves. Plants need a source of energy to germinate before they can begin photosynthesizing in the first place (Ai and Jane 2016). Yet when we take these foods out of context and feed them to organisms who are not adapted to them, we introduce a state of mismatch into their environments and ours. We are the next level up in this food chain, and a tighter balance of omega-3:6 is optimal for human health (DiNicolantonio and O’Keefe 2018; Taha 2020). Given the ramifications, why not first consider ecology when making food production decisions? Further, energetically, it would be better yet to skip feeding plants to animals and to eat the plants directly (Bonhommeau et al. 2013). This ecology-first approach is one great benefit from regenerative farming, which treats food systems as natural ecosystems.

Further, what can we learn from supplement markets that often extract “active ingredients” and reduce them to molecules? Do these molecules always carry the same physiological effects as their counterparts in food? For example, do omega-3 pills carry the same benefits as eating wild-caught fatty fish (ASCEND 2018, Aung et al. 2018; Bhatt et al. 2019; Hu et al. 2019; Manson et al. 2019)? Synergistic effects often emerge when eating whole foods, which can be lost when reduced to molecular building blocks (Pollan 2008). Considering the promise of cultured foods—whether as lab-grown muscle cells (from animals) or lab-grown meats (from plants)—we must think hierarchically to optimize outcomes. This framework transcends molecular, cellular, and organismic physiology. The hierarchy of food production matters since food scientists use individual molecules to enhance flavor or texture, in addition to biotechnological tools to source whole food constituents (e.g., a genetic lineage of maximally healthy muscle cells) (MacQueen et al. 2019; Furuhashi et al. 2021). If we are tailor-making plant-based steaks to create the “marbling” that people want (using omega-6 rich sunflower oils), then we must evaluate the public health consequences of our ingredients (Southey 2021; van Vliet et al. 2021). Do we want the equivalent of corn-feed beef because we did not take an appropriately integrative approach when culturing food?

We need to be careful not to create a public health crisis while trying to feed humanity. At scale, this is precisely what is happening with industrial agriculture. Most current agricultural staples are easily digestible carbohydrates that contribute to obesity, type 2 diabetes, metabolic syndrome, among various health problems (Taubes 2007; FAO 2020e; FAO et al. 2020). Therefore, the future of food is also about the ethics of human rights and giving people quality products that optimize health. If a goal over the next 30 years is to sustainably feed humanity without creating environmental or health crises, then there is much potential to flourish. Let us learn from current oversights so that we do not introduce them into innovative technologies. This applies to how food production affects the global environment and public health, and extends to zoonotic diseases and ethics as well.

Probably the greatest promise of emerging food technologies is the potential to feed humanity at scale without contributing to the environmental and ethical problems that underpin current mainstream practices. We will need a portfolio involving a combination of methods described above. With those in place, the risk of pandemic diseases, environmental impacts, and ethical mistreatment decreases. By their nature, zoonoses are diseases that humans catch from other animals. With regenerative farming practices and cultured foods from lab-controlled environments, the likelihood of zoonoses becomes exceedingly small. Comparatively, high-density farms and wild-caught animals present a vastly greater risk category. In addition, the potential for animal suffering approaches near-zero with cultured meats at the cellular level. At the organismic level, regenerative farms provide healthy environments and quality lives for domesticated animals to live and thrive in their ecosystems.

In summary, while it is important to feed the people, we also need to cease wildland conversion to agriculture and minimize all other impacts on wild biodiversity. Further, we should emphasize the sustainable use of land that we dedicate to agriculture (e.g., eating low on the food chain, intercropping to replenish soil, three-dimensional farming), move away from any use of wild caught food at scale (including fishing), and employ food production technologies as they become more energetically, monetarily, and environmentally effective than current practices.

5 Closing Remarks

Humanity uses nearly all suitable agricultural land, and has greatly impacted biodiversity while converting them (Martenson 2011; Ritchie and Roser 2013; Ritchie 2017, 2019). Natural lands must be protected to allow our relatives in the tree of life the space to survive. To feed humanity, this means that agricultural efficiency needs to increase tremendously while converting virtually no more land to agriculture. Even plant-based agriculture requires sustainable transformation. This includes implementing polycultures over monocultures, hydroponics and aquaponics powered by alternative energy, improved irrigation methods, the conservation of natural habitats, and the overall lessening of environmental impacts. If we can execute on this, then even plants and soil microbes will have healthier lives.

Further, suppose we can transform plant agriculture and pair it with alternative food production technologies powered by clean energy at scale. In that case, we have a shot at sustainably producing food for 10 billion people, for at least awhile. Yet exponential population growth cannot persist; we would need to grow more food every year. As discussed above, a population at 10 billion is not sustainable if we raised everyone's standard of living and consumption to levels currently present in developed countries such as the United States. Thus, unless we can continue changing human carrying capacity, the global population will need to reverse its current growth, and trend downward (Hall and Day 2009). Promisingly, data and modeling suggest precisely this kind of trend, with the global population peaking in 2064 and declining into 2100 (Vollset et al. 2020).

Our current situation arose from the self-centered actions that underlie our behavior. It would be wise to respect the proper place of other organisms in the environment that we all share. Transitioning from selfish thinking will require us to see that we are one lineage among millions in an interdependent tree of life. We are not superior to other organisms nor to the environments that we inhabit. We are a subset of nature, reliant upon its resources, and our livelihood depends upon accepting this. With a targeted strategy, we can divert and correct our path. We live amid a human behavior problem, not a human technology problem. Humanity currently possesses the tools to thrive sustainably on the earth while venturing into the cosmos. Within a reasonably short timeline, we need incentives and consistent policies to make this happen. These actions are necessary to prevent the negative feedbacks of our current behavior from catching up with us (Turner 2014; Jackson 2016; Foxon 2017; van den Bergh 2017; Hausfather and Peters 2020).

In all honesty, it is not clear if Homo sapiens will make the necessary transitions; we have been selfish throughout our short history. But if we can accomplish them, we will find ourselves in a place where we can live sustainably alongside nature while deploying sophisticated tools to support our unique phenotype. It does not make us less special to exist thoughtfully, with foresight for our future and consideration for our family (the rest of life on Earth). On the contrary, owning our shortcomings will allow us to overcome our predicaments. At that point, embracing humility and leaving speciesism behind will make us far more precious than our fragile exceptionalism has ever prescribed.