Hear the phrase “the animal kingdom,” and the first image that comes to mind is likely elephants, lions, and giraffes roaming a savannah, tigers, parrots, and monkeys ruling the jungle, or maybe even sharks, turtles, and fish swimming in the ocean. You probably won’t picture a cow shoved into an indoor feedlot, or a human sitting at their desk on a computer.
Unfortunately, our common perception of the animal world is severely out-of-date. In the past century, human population growth and agricultural expansion has transformed the structure of Earth’s ecosystems and pushed most major fauna to the brink of extinction. As of 2015, wild animals only accounted for 4% of global mammalian biomass (measured in tons of carbon). Humans made up 34%, and livestock came in at a whopping 62%, meaning that domestic animals account for over 30 times the total biomass of wild terrestrial animals and 15 times the biomass of wild marine animals. Cattle alone weighed almost ten times as much as all wild animals on the planet combined.
We are living in the midst of the sixth mass extinction on Earth, defined as a short period of geologic time when a high percentage of biodiversity dies out. Over 65.5 million years ago, such a mass extinction eradicated the dinosaurs of the Jurassic era. The Earth has naturally undergone physical and chemical changes throughout geologic history, alternating between glacial and interglacial states due to the cyclical growth and retreat of ice sheets over periods of approximately 100,000 years. These routine changes are caused by fluctuations in the atmosphere’s chemical makeup resulting from carbon weathering and mineral cycling as well as shifting orbital patterns and axial tilt of the planet. But unlike any previous extinction, humans – and particularly agricultural systems – are the driving force behind modern biodiversity loss, and we are experiencing global change at an unprecedented speed.
How did we get here? By prioritizing the rapid expansion of industrial agriculture at the expense of our ecosystems: trading out forests for farmlands, big cats for cattle, and locally-grown produce for processed meats and fast foods. Experts agree that agriculture is a more significant threat to biodiversity than climate change. Nearly 75% of the world’s threatened species are affected by farming and the associated overuse of natural resources, compared to 19% of species facing direct threats from global temperature changes. This makes sense given that agriculture accounts for over 90% of global deforestation and 70% of freshwater use, destroying natural habitat for a majority of animals on the planet and causing severe disruption to our ecosystems.
Humanity has been present for a mere blink of an eye in the grand scheme of Earth’s history, and we have already wiped out at least 680 vertebrate species, threatening over 1 million more species with extinction in the next few decades. Within our lifetime, children could grow to consider elephants as foreign as the wooly mammoth or rhinoceroses as distant as the tyrannosaurus rex. Studies have already shown that elementary school children are better able to identify Pokemon characters than native wildlife, a generational disconnect reflective of a time when most people only interact with other species at the dinner table.
For communities around the world that have developed close relationships with other species over thousands of years and tied significant traditions and spiritual value to other species, the loss of wildlife perpetuates a loss of cultural identity. For example, dwindling salmon populations in the Klamath River have forced indigenous tribes throughout California to abandon ceremonies and cultural practices tied to the keystone species and suffer from food insecurity.
On a practical level, biodiversity is essential for human survival. It ensures the persistence of ecosystem functions such as natural water filtration, soil formation, nutrient cycling, climate regulation, and the amount of food energy converted to biomass. With severely disproportionate populations of humans and domestic animals and barely any wild species, we are pushing past the planet’s capacity to sustain human life and diminishing the productivity of our environment.
People and domesticated species are also facing severe health risks due to shrinking genetic variation. The homogeneity of the modern mammalian gene pool allows for increased spread of infectious disease, hindering our population’s resistance to pathogens. The inbreeding of livestock has also allowed for increased genetic disorders and viral outbreaks, which crossover to human populations through the consumption of meat and dairy products.
Biodiversity is what makes our planet not only habitable, but also beautiful and unique. Wildlife has fascinated humans for centuries, serving as inspiration for art, literature, and media and playing an important role in our scientific and cultural understanding of the natural world. And most people don’t want to see species like elephants, tigers, or polar bears move from critically endangered to extinct – but to save the wildlife we admire, we have to start by looking at our plates.