The necessity of animals for human existence extends far beyond simple matters of food and companionship. Animals provide complex, interwoven ecological functions, profound scientific advancements, and significant psychological benefits. Their roles encompass maintaining the planet’s fundamental stability, advancing medical knowledge, and supporting human mental well-being. Understanding this necessity requires recognizing the pervasive, often unseen, roles animals play in sustaining the systems that support life on Earth, from enriching the soil to developing life-saving treatments in laboratories.
Ecological Services Maintaining the Planet
Animals function as the operational machinery of global ecosystems, performing biological roles that govern soil fertility and plant life. A primary function is the movement of plant genetic material through seed dispersal, often performed by vertebrates like birds and mammals. This dispersal occurs either through endozoochory, where seeds pass through a digestive tract, or epizoochory, where seeds cling to fur or feathers. Large or migratory animals facilitate long-distance seed dispersal, promoting gene flow and allowing plant populations to adapt to changing environmental conditions.
The movement of nutrients and the aeration of soil rely heavily on invertebrate activity. Earthworms create intricate underground pathways that allow oxygen and water to penetrate the soil structure. Their castings are rich in nutrients, significantly enhancing soil fertility.
Insects, including millipedes and beetles, contribute to the breakdown of decaying matter by physically fragmenting dead plants and animals. This accelerates decomposition, making essential nutrients like nitrogen, phosphorus, and potassium available for plant absorption. In arid environments, macro-arthropods such as termites create burrows that enhance water infiltration and buffer temperature extremes. These actions are fundamental to the global cycles that sustain terrestrial biomass.
Direct Resources: Food, Materials, and Labor
Animals serve as a direct source of sustenance and industrial raw materials for human civilization. Food provision includes basic meat and dairy, as well as specialized products like honey from bees and fish and shellfish supplying essential omega-3 fatty acids. Dairy products from cows, goats, and sheep are processed into nutritional staples like cheese and yogurt, providing concentrated sources of calcium and protein.
Animals also yield a range of materials used in manufacturing and industry. Natural fibers integral to the textile industry include wool, cashmere, and silk. Animal byproducts contribute to non-food items:
Gelatin derived from collagen, used in pharmaceuticals and photography.
Tallow from cattle fat, used in the production of soaps and lubricants.
Specific animal components historically used in medicine, such as insulin extracted from pigs and cattle before synthetic alternatives were available.
Animals provide a tangible source of power through labor and transportation, a utility still relevant globally. Draft animals, including oxen, water buffalo, and horses, are trained to pull heavy loads. Oxen are suited for heavy tasks like plowing in wet soil and are still used in agricultural regions of Africa and Asia. Furthermore, animals can be used for generated power, such as walking on a treadmill to run small machines for grinding grain or irrigation.
Advancements in Human Health and Science
The scientific understanding of human biology and the development of modern medicine rely extensively on animal models. Animals provide complex, whole-organism systems due to their genetic and physiological similarities to humans, systems which cannot be fully replicated by cell cultures or computer simulations. Mice and rats are the primary models used in research because 98% of human genes have a comparable gene in the mouse. Their short life cycles and rapid reproductive rates allow researchers to study biological processes across generations and model human diseases effectively.
Specialized animal models are selected based on unique physiological traits that mimic specific human conditions. Rabbits have been instrumental in studying cardiovascular diseases like hypertension and were historically used to develop the rabies vaccine. Non-human primates are irreplaceable for studying complex neurological and infectious diseases, such as Alzheimer’s, Parkinson’s, and HIV, because these diseases do not occur naturally in other models.
New treatments, including vaccines and pharmaceuticals, must be rigorously tested in a living system before human trials commence. For example, the polio vaccine was developed and tested using monkeys. Furthermore, studying animals with unique biological features, such as nerve regeneration in salamanders, offers insights that may inform future human therapies for injuries.
Psychological and Therapeutic Roles
The presence of animals offers measurable benefits for human psychological and emotional health, extending beyond simple companionship. Pet ownership is associated with reduced stress and anxiety, as interaction with an animal can trigger a physiological calming effect and boost mood. For individuals dealing with long-term mental health problems, a personal pet often provides security and stability, offering a reliable, non-judgmental presence.
Animals are formally integrated into healthcare through Animal-Assisted Therapy (AAT) programs for physical and psychological rehabilitation. This structured approach uses the human-animal bond to help patients achieve specific therapeutic goals. Examples include improving fine motor skills by brushing an animal or enhancing social skills through interaction with a therapy animal. The non-judgmental nature of animals, such as horses used in equine-assisted psychotherapy, encourages individuals with anxiety or trauma to engage more openly in treatment.
Assistance animals provide highly specialized support, allowing humans to navigate the world with greater independence and safety. These include seeing-eye dogs for the visually impaired or service dogs trained to detect oncoming seizures or low blood sugar levels. These animals perform specific tasks that mitigate a person’s disability, directly improving their quality of life. The bond formed in these relationships also provides emotional support, contributing to the human partner’s overall mental resilience.