An omnivore is a species that consumes both plant and animal foods, exploiting whatever energy sources the environment offers. Humans and pigs are textbook examples, alongside bears, rats, and chickens. The omnivorous digestive system is generalised rather than specialised: moderate gut length, versatile dentition with both cutting and grinding teeth, and metabolic pathways able to handle varied macronutrient mixes. This flexibility underpinned human evolution, allowing survival across climates and seasons by switching between hunted, fished, gathered, and later farmed foods. In nutrition, omnivory explains both our adaptability and our vulnerability: we can thrive on many dietary patterns, but the same opportunism makes energy-dense modern food environments easy to overconsume. The ethics and sustainability of omnivorous diets, particularly meat consumption, are among the most debated topics in food policy.