Tinbergen's Four Questions
In 1973, Nikolaas Tinbergen won the Nobel Prize in Physiology or Medicine alongside Karl von Frisch and Konrad Lorenz for their discoveries in organizing individual and social patterns of behavior in animals. An eminent ornithologist and ethologist, Tinbergen studied biology at Leiden University and later taught at the University of Oxford. During this time, Tinbergen elaborated four complementary categories of explanation for animal behaviors. These categories are colloquially called ‘Tinbergen’s 4 Questions,’ and include a comprehensive overlap of evolutionary psychology, sociobiology and behavioral ecology. The four categories posited by Tinbergen are phylogeny, ontogeny, mechanism, and adaptive value.
Phylogeny is the history of the evolutionary changes in a species. It is essentially the examination of a species across multiple generations and traits retained by the species from earlier evolution. Ontogeny is the developmental explanation for changes in an individual organism. It is the gene-environment interaction of individuals, including imprinting and other acquisitions of new behaviors as a combination an individual’s genetics and environment. Mechanism refers to the mechanistic causal and functional explanations for how an organism exhibits a given behavior in a biochemical context. Brain neurobiology and the release of neurotransmitters, hormones and pheromones are mechanistic explanations of an animal behavior. Adaptive value is the value of a trait that evolved over time in a population as a means of improving survival or sexual fitness in an environment. It is the Neo-Darwinism’s synthesis of Mendelian genetics and Darwin’s theory of evolution by natural selection that helps describe adaptive value.
Tinbergen’s four questions are also grouped into two categories describing scope: proximate or ultimate. The proximate view is concerned with describing how an individual organism’s structures function, and encompasses both ontogeny and mechanism. Ontogeny describes how an individual functions in terms of the relationship between its genetics and its environment. Mechanism describes the biochemical source of an evolved behavior. The ultimate view describes why a species evolved the given structures or adaptations it has, and includes phylogeny and adaptation. Adaptive value demonstrates the purpose of evolutionary traits as an improvement in overall fitness of the individual through the modification of behaviorally expressed phenotypes. The unique history of a species’ evolution in phylogeny helps to describe why a species evolved specific structures.
This categorical examination of animal behavior allows us to closely explore the different aspects of what a particular animal behavior is, why it happens and what purpose it serves for the animal. By using Tinbergen’s four categories, we can consider the behavior of Emperor penguins kidnapping offspring in the context of developmental history, fitness, environment and genetics.