Natural Behaviour Is Not Enough: Farm Animal Welfare Needs Modern Answers to Tinbergen’s Four Questions

**Background:** The term 'natural behaviour' is widely used by food companies and retailers as a metric for good animal welfare, despite decades of scientific criticism. This reliance stems from outdated ethological models—particularly Konrad Lorenz's drive theory and W.H. Thorpe's connection between instinct suppression and suffering—which assumed that preventing natural instinctive behaviours causes emotional disturbance. The author argues that on the 60th anniversary of Tinbergen's Four Questions framework (1963), this approach needs updating with modern evidence on what animals actually value.

**Methods:** This is a narrative review that applies Tinbergen's four questions (ontogeny, causation, adaptation, phylogeny) to critique the natural behaviour concept and synthesise evidence from animal welfare science on methods for assessing what animals value. The author reviews published studies using spatial distribution, time spent near resources, approach/avoidance tests, choice and preference tests, conditioned place preference/aversion, and instrumental (operant) conditioning.

**Key Results:** The review presents several lines of evidence: (1) Lorenz's drive theory has been largely discarded because it fails to explain real behaviour and relies on unspecified 'motivational energy'. (2) Natural behaviour can indicate poor welfare—behaviours such as hiding from predators, scratching, or constant food-searching occur during fear, discomfort, or nutrient deficit. (3) Modern methods show what animals value: laying hens will peck a key for access to straw; pigs, calves, and shorn sheep operate switches for heat; heifers learn to operate a panel for 15 min of lying down; calves push a panel for social contact. (4) Dairy cows at a choice point chose pasture over indoor stalls 66.2% vs. 33.8% of the time, though overall they spent more time indoors depending on weather and time of day. (5) Pigs and chickens avoid ammonia at concentrations as low as 10 ppm. (6) Dairy cows will pay as high a price (pushing heavy gates) for access to automated rotating brushes as they will for food when food-deprived for 1.5 h. (7) Sheep showed progressive slowing and reluctance to approach a corridor endpoint after experiencing electro-immobilisation, indicating strong aversion. (8) Artificial selection—e.g., for rapid growth in broiler chickens—has caused skeletal problems, obesity, and feed restriction needs, showing that modern farm animals differ substantially from wild ancestors.

**Clinical Implications:** The paper concludes that natural behaviour alone is an unreliable welfare indicator because it lacks evidence of whether performance or non-performance matters to the animal. Instead, welfare assessment should prioritise what animals value, measured through their willingness to work for rewards. This requires: (a) using existing scientific evidence on species-specific rewards; (b) conducting new collaborative research between academia and commercial farms to find practical, scalable ways to provide valued resources; and (c) recognising that welfare involves balancing what animals value in the moment with long-term physical health. The author emphasises that Tinbergen's framework remains valuable but must be updated with modern knowledge of behavioural causation, development, adaptation, and the effects of domestication through artificial selection.