increasing the chance that an organism will survive to reproduce. For example, the function of chlorophyll in a plant is to capture the energy of sunlight for photosynthesis, which contributes to evolutionary success. In ethology The ethologist Niko Tinbergen named four questions, based on Aristotle's Four Causes, that a biologist could ask to help explain a behaviour, though they have been generalised to a wider scope. 1) Mechanism: What mechanisms cause the animal to behave as it does? 2) Ontogeny: What developmental mechanisms in the animal's embryology (and its youth, if it learns) created the structures that cause the behaviour? 3) Function/adaptation: What is the evolutionary function of the behaviour? 4) Evolution: What is the phylogeny of the behaviour, or in other words, when did it first appear in the evolutionary history of the animal? The questions are interdependent, so that, for example, adaptive function is constrained by embryonic development. In philosophy of biology Function is not the same as purpose in the teleological sense, that is, possessing conscious mental intention to achieve a goal. In the philosophy of biology, evolution is a blind process which has no 'goal' for the future. For example, a tree does not grow flowers for any purpose, but does so simply because it has evolved to do so. To say 'a tree grows flowers to attract pollinators' would be incorrect if the 'to' implies purpose. A function describes what something does, not what its 'purpose' is. However, teleological language is often used by biologists as a shorthand way of describing function, even though its applicability is disputed. In contemporary philosophy of biology, there are three major accounts of function in the biological world: theories of causal role, selected effect, and goal contribution. Causal role Causal role theories of biological function trace their origin back to a 1975 paper by Robert Cummins. Cummins defines the functional role of a component of a system to be the causal effect that the component has on the larger containing system. For example, the heart has the actual causal role of pumping blood in the circulatory system; therefore, the function of the heart is to pump blood. This account has been objected to on the grounds that it is too loose a notion of function. For example, the heart also has the causal effect of producing a sound, but we would not consider producing sound to be the function