Our reliance on the animal kingdom extends beyond domesticated species and the food supply chain. Understanding this dependency involves examining the immediate resources animals provide, the foundational services they perform for the planet, and their unique contributions to modern health and well-being. The inquiry into whether we need animals to survive is fundamentally an inquiry into the stability of our entire ecological support system.
Direct Resource Provision
Animals serve as a primary source of high-quality nutrition for billions globally. Terrestrial animal-source foods, such as meat, milk, and eggs, deliver protein alongside important micronutrients like vitamin B12, iron, and zinc. These products support the food security and livelihoods of approximately 1.3 billion individuals. In aquatic environments, fish provide roughly 20% of the average per capita animal protein intake for an estimated 3 billion people.
Beyond nutrition, animals furnish materials necessary for agriculture and industry. Livestock indirectly support crop cultivation through the provision of manure, which acts as a natural fertilizer. Hides and wool supply raw materials for clothing and various industrial applications. Although synthetic alternatives exist for some of these products, the current global system relies heavily on animal production to meet the vast demand for these tangible resources.
Essential Ecosystem Services
The foundational contributions of the animal kingdom are the large-scale ecological processes that maintain the planetary environment. One such process is pollination, performed largely by insects and other animals. Approximately 75% of the world’s global crop types benefit from animal pollination, including most fruits, vegetables, and nuts. Animal-pollinated crops account for about 35% of global food production by volume.
The stability of the global climate also relies heavily on animal activities, particularly in the oceans. Marine life contributes to carbon sequestration through the biological carbon pump. Zooplankton consume photosynthetic organisms and produce carbon-rich fecal pellets that sink rapidly to the deep ocean, removing carbon dioxide from the surface waters. Larger marine animals, such as whales, influence this cycle by stimulating the growth of phytoplankton. Ocean biology sequesters an estimated 10 billion tonnes of carbon dioxide annually.
Animals also play a significant role in decomposition and nutrient cycling on land and in water. Detritivores and scavengers break down organic matter, recycling nitrogen, carbon, and phosphorus back into the soil and water. This process is necessary for maintaining soil fertility, which underpins all terrestrial food production systems. Without the constant work of these organisms, ecosystems would become clogged with undecomposed material, halting the nutrient flow that sustains plant life.
Advancements in Human Health
The animal kingdom provides a living laboratory integral to preventing and treating disease. Animal models are frequently used in medical research to understand physiological processes and test the safety and efficacy of new treatments. Rodents, primarily mice and rats, constitute approximately 95% of all laboratory animals used in biomedical research. These species are utilized extensively for studying complex human conditions, including cancer, Alzheimer’s disease, and diabetes.
Research using animal models has been instrumental in almost every major medical breakthrough of the last century. Non-human primates have been used in the development of vaccines for diseases like HIV and in studies during the COVID-19 pandemic. The knowledge gained has led to the creation of antibiotics, the synthesis of insulin for diabetes management, and the refinement of surgical techniques, such as organ transplantation.
The Survival Implications of Biodiversity Decline
The decline of animal populations represents a systemic threat to human survival by compromising the stability of our support systems. Habitat destruction, a major driver of biodiversity loss, increases the frequency of contact between humans and wildlife. This increased interaction elevates the risk of zoonotic spillover, where pathogens jump from animals to people. Over 75% of emerging infectious diseases in humans are caused by pathogens that originated in animals.
The loss of species diversity increases the risk of human exposure to zoonotic pathogens. When ecosystems are simplified, the remaining animal species are often better hosts for pathogens, leading to higher rates of disease transmission. The collapse of wild animal populations translates into compromised food chains and a reduced capacity of natural systems to regulate climate, threatening the long-term viability of human civilization.