How Human Carnivory Harms Global Biodiversity

The ethical issues around meat consumption are familiar to many animal advocates. Indeed, moral stances, health, and environmental concerns are three major reasons why people become veg*n. The environmental motivations for veg*nisms have mostly been studied in terms of impacts on specific species or ecosystems, rather than quantitatively and at the level of global biodiversity. In this study, a team of researchers revealed that meat consumption threatens roughly 25% of vertebrate species—and this, they note, is a conservative estimate. For some “classes” (for example, amphibians) and habitats (such as the oceans), this figure is even higher.

To conduct their study, the team used the International Union for Conservation of Nature Red List of Threatened Species (IUCN Red List) Database. Among the 46,000+ vertebrate species included in the dataset, the researchers randomly sampled 1,000 and categorized them as fishes, amphibians, reptiles, birds, or mammals, dividing further by habitat and ecosystems. They then identified five general mechanisms by which human carnivory might be threatening a species towards extinction, including:

• Predation: Including killing wild animals and egg collection, as well as bycatch.
• Competition: Including depletion of prey animal populations and killing animals who threaten agriculture and other human activities.
• Biohazards: Namely the mixing of farmed and wild populations (for example: disease spreading from farmed animals to nearby wild animals).
• Environmental Degradation: This typically occurs through destructive farming practices, raising farmed animals, agriculture, and climate change.
• Miscellaneous Factors: For example, climate change and killing animals to be used as bait/food and hunting.

Their results paint a dismal picture for vertebrates. Furthermore, different classes of animals and habitats are impacted in unique ways. To illustrate, across all vertebrates, predation is the most damaging, affecting 11.9% of all species. This is trailed by farmed animals, which affect 10.8% of vertebrates, bycatch at 5.4%, and biohazards at 3.3%. While this “ranking” applies to birds and mammals, it’s different for fishes.  The second biggest impact on fishes comes from bycatch, rather than farmed animals Meanwhile, for amphibians and reptiles, farmed animals present by far the greatest threat For animals living in aquatic environments, biohazards are particularly damaging.

Taken together, the authors’ main point is that human carnivory, among all human-caused factors contributing to extinction and biodiversity loss, is uniquely threatening. It could explain the lion’s share of the ongoing global decline of the world’s vertebrate species. Predation, farmed animals, and bycatch—all practices that are directly involved with the meat production process—are by far the three most damaging and impactful mechanisms by which human carnivory threatens species. 

Grim as these conclusions are, the authors argue that they offer opportunity. We can act on this newfound awareness and change our behaviors, policies, and cultures to accommodate the threats posed by and associated with biodiversity loss. Examples might include taxing the production of animal products, eliminating subsidies to animal agriculture and fisheries sectors, campaigns to bring attention to the costs of meat consumption, and supporting innovative, plant-based brands and markets. These are all angles that animal advocates have been working on and will do well to continue, in hopes of creating a more just, sustainable future.