# data[].attributes.body
Main Contribution
Author of On the Origin of Species (1859).
Darwin (1859) conceptualised and proved the theory of evolution by natural selection, a foundational idea in modern biology. He embarked on a five year world-travelling voyage in 1831, during which he was fascinated by fossils and the unique adaptations of different Galapagos island tortoises and finches, among other things, all of which helped prove his theory (Cain et al., 2020).

Advancements in Ethology and Wider Field
While Darwin’s ideas were criticised when first proposed they are now widely accepted and form the basis of modern evolutionary biology. Darwin’s third substantial exploration of evolutionary theory The Expression of the Emotions in Man and Animals (1872) was highly influential to ethologists of the time, where he investigated if the origins of certain human behaviours can be found in the world of animals. In an article Bara, Lazcano and Peretó (2009) discuss how Darwin’s critical thinking and doubt of the theory of spontaneous generation of organisms allowed him to devise his revolutionary theories about evolution which still heavily influence many fields of modern biology, including ethology.

Modern Research Example
Carvalho, C. F. D., Crespi, B. J., Farkas, T. E., Feder, J. L., Gompert, Z., Nosil, P., … Villoutreix, R. (2018). Natural selection and the predictability of evolution in Timema stick insects. Science, 359(6377), 765-770. https://doi.org/10.1126/science.aap9125

A group of scientists use Darwin’s theory of evolution by natural selection in an attempt to determine the predicability of evolution. They used Timema stick insects and measured how their colouration and patterning changed over generations to test if they could predict the course of the change in the colouration, but our limited understanding of the many selective pressures in our environment made this prediction difficult to make.

# data[].attributes.headline
Ivan Pavlov 1902 - Classical Conditioning

# data[].attributes.subject
Ivan Pavlov 1902 - Classical Conditioning

# data[].attributes.body
Main Contribution
Clark (2004) explains how Pavlov accidentally demonstrated the concept of classical conditioning. While investigating salivary responses in dogs Pavlov recognised that the dogs learned that footsteps of an approaching scientist meant it may be time for food, and so salivated more when they heard said footsteps. This led to further experiments in 1902 where Pavlov’s conditioning resulted in dogs associating the sound of a bell with food and so salivating at only the sound of the bell.

Advancements in Ethology and Wider Field
Now, classical conditioning is a fundamental framework of the study of learned behaviour in humans and other animals. Brom, Both, Everaerd, Laan, and Spinhoven (2014) discuss the widely accepted belief that classical conditioning contributes significantly to the etiology of both expected and unexpected animal behaviours, showing how Pavlov’s investigation into this type of conditioning has contributed hugely to the development of the field of ethology and others like psychology and cognitive science.

Modern Research Example
Antemann, V., Chakroborty, N. K., Eisenhardt, D., Felsenberg, J., Gehring, K. B., Menzel, R., … Stollhoff, N. (2011). Average group behaviour does not represent individual behaviour in classical conditioning of the honeybee. Learning & Memory, 18(11), 733-741. https://doi.org/10.1101/lm.2232711

A study conducted by a group of scientists who classically condition honey bees to accociate certain odours with certain situations to analyse whether or not the learning capabilities of individual bees reflected that of the entire conditioned population.  As is concluded in the title, the scientists found individual bee behaviour did not correlate directly with that of the population as a whole.

# data[].attributes.body
Main Contribution
Author of The Companion in the Environment of Birds (1935).
Lorenz (1935) experimented with the natural phenomenon of imprinting, particuarly in birds, in which chicks associate themselves with the first large moving object they see and view it as a parental figure. His first experimental success involved seperating a dozen eggs before they hatched, leaving six underneath the goose and incubating the rest. Once hatched, six chicks followed the mother goose, and six followed Lorenz. Lorenz’ work inspired a genetic outlook on behaviour still prevalent in ethology today, as his work puts into question which behaviours are learned and which are innate (McLeod, 2018).

Advancements in Ethology and Wider Field
Parental imprinting has since been observed and investigated in other species, such as cows. Kent (2020) explains how female cows isolate themselves from the herd in order to give birth, and spend time alone with their calves immediately after birth in order to develop a mutual bond and so that the calves recognise their mothers. More recently links between imprinting and endochrinology have been established. Biechl et al. (2019) discuss the hormonal regulation of the short time period in which olfactory imprinting in larval zebrafish must occur to allow for proper navigation around a reef, showing how certain ethological concepts related to imprinting can be linked to the physiology of an organism.

Modern Research Example
Kacelnik A., Martinho-Truswell, A., & McGregor, B. (2018). Ducklings imprint on chromatic heterogeneity. Animal Cognition, 22(5), 769-775. https://doi.org/10.1007/s10071-019-01273-2

Three scientists investigate preferential imprinting of mallard ducklings in terms of the chromatic heterogeneity, or difference in colour of stimuli. Ducklings were tested for their preference between two stimuli, one heterogeneous meaning with different colours, and one homogeneous meaning of the same colour. They found that after exposure to a stimulus made up of different colours the average duckling had a preference for the same kind of stimulus later on, and that the same was true when the stimulus was substituted to one made up of one colour.

# data[].attributes.headline
Nikolaas Tinbergen 1951  – The Four Questions 

# data[].attributes.subject
Nikolaas Tinbergen 1951  – The Four Questions 

# data[].attributes.body
Main Contribution
Author of The Study of Instinct (1951).
Tinbergen (1951) investigated the logistics of an organised, hierarchical system of behaviour involving repetitive behaviours dependent upon stimuli and the need for satiation culminating in fixed action patterns of various complexities. The example Tinbergen investigated most would be the reproductive instincts of male three-spined stickleback fish, of which the scientist devised a hierarchical fixed action pattern of behaviours dependent on a host of external stimuli and also dependent on each other.

Advancements in Ethology and Wider Field
As is explained by Davies and Krebs (1993), one of Tinbergen’s most profound contributions to ethology published in his 1963 article ‘On aims and methods of ethology’ was his emphasis of the fact that there are many more ways than one to answer the question ‘Why?’ when studying behaviour, and his subsequent attempt to come up with answers using four questions of his own. Firstly, Tinbergen (1963) ponders behaviour in terms of causation and ontogeny, which study the proximate influences on behaviour such as courtship behaviours and daylight stimulated hormone production. Secondly, in terms of adaptive value and evolutionary history, which study the ultimate influences on behaviour like selective evolution of more attractive birdsongs. These questions led to a modern evolutionary outlook on behaviour, important for the progression of ethology.

Modern Research Example
Calisi, R. M. (2014). An integrative overview of the role of gonadotropin-inhibitory hormone in behavior: Applying Tinbergen’s four questions. General and comparative endochrinology, 203, 95-105.https://doi.org/10.1016/j.ygcen.2014.03.028

Calisi (2014) applies Tinbergen’s four questions framework in an attempt to bridge the gap in understanding between the molecular knowledge of gonadotropin-inhibitory hormone (GnIH) and its influence on animal behaviour. Using the four questions she is able to divulge a more detailed insight into proximate and ultimate behavioural mechanisms influenced by the secretion of GnIH.

# data[].attributes.headline
Burrhus Frederic Skinner 1957  - Operant Conditioning 

# data[].attributes.subject
Burrhus Frederic Skinner 1957  - Operant Conditioning 

# data[].attributes.body
Main Contribution
Co-author of Schedules of Reinforcement (1957).
Ferster and Skinner (1957) revolutionised ethology after publishing their work. They proposed an additional framework of conditioning, operant conditioning, on the basis that organisms could be reinforced according to different schedules, and that different schedules produced an array of different behaviours. They also added that when and how these schedules are reinforced had significant effects on the strength and longevity of the desired result of the conditioning.

Advancements in Ethology and Wider Field
Morgan (2017) states that the operant framework of conditioning has since contributed greatly to the study of behavioural pharmacology, choice behaviour, and behavioural economics. Using the schedules proposed by the authors above, scientists are now able to take more informative deductions when observing animals make choices in order to better understand how exactly the animal makes choices. Reinforcement schedules are also commonly used in trials to evaluate the abuse potential of new pharmaceuticals, showing how greatly this framework has contributed to the many subdivisions of behavioural science.

Modern Research Example
Costa, R. M., DeRusso, A. L., Fan, D., Gupta, J. Shelest, O., & Yin, H. H. (2010). Instrumental uncertainty as a determinant of behaviour under interval schedules of reinforcement. Frontiers in Integrative Neuroscience, 4. https://doi.org/10.3389/fnint.2010.00017

A group of scientists use different schedules of reinforcement on mice to assess the effect of uncertainty on habit formation. They found that after a small amount of conditioning, mice conditioned with both random and fixed interval schedules could learn to press a lever for a food pellet, but that this behaviour wasn’t a habit and was susceptible to devaluation. After more conditioning, mice conditioned with random interval schedules with more uncertainty exhibited habitual lever pressing, while mice conditioned with fixed interval schedules with less uncertainty continued to only be goal driven. This led them to hypothesise that schedules with higher uncertainty contribute to the development of habits.

# data[].attributes.headline
Nobel Prize in Physiology or Medicine 1973

# data[].attributes.subject
Nobel Prize in Physiology or Medicine 1973

# data[].attributes.body
Awarded to Lorenz, Tinbergen and von Frisch for ‘discoveries concerning organisation and elicitation of individual and social behaviour patterns’ (Karolinska Institutet, 1973).