Evolution and Behaviour Flashcards
What can psychologists gain by studying animal behaviour?
What is psychology?
Psychology: The scientific study of the human mind and behaviour
Behaviour: Co-ordinated responses of whole living organisms to internal or external stimuli
Why study animal behaviour?
- interesting
- to inform conservation (massive extinction crisis)
- to inform animal welfare
- to understand universal threads in behaviour (general organisation of behaviour)
- to compare behaviour and mind across species (different suggest explanations)
- to provide models for understanding human behaviour
What are the universal threads in behaviour?
Universal threads in behaviour
All organisms face common, recurrent problems that must be solved…
- Acquiring energy for life (nutrients,water)
- Reproducing
- Ensuring offspring reach sexual maturity
…Surviving long enough to achieve all of the above!
Studying a range of different solutions to these common problems sheds light on possibilities and constraints facing any organism –including humans
We can also gain insights into commonalities and differences in solutions between individuals (or groups of individuals):
•Why are there differences between sexes?
•Why do the males of so many species fight more than the females?
•Why do males of most species die younger than females?
•Why do individuals choose the mates they do?
•Why are females/males sometimes promiscuous and sometimes monogamous?
What approaches do we use to study animal behaviour?
Early Natural History
Gilbert White focuses on animals in their environment, but descriptive; not generating and testing hypotheses
Observation is a useful starting point to generate hypotheses, and track long-term changes.
Behaviourism:
views all behaviour as a response to a specific stimulus
Pavlov’s experiment with dogs, when he rang a bell the conditioned stimulus gave the dogs its dinner, the unconditioned stimulus it would soon start to salivate when it heard the bell before seeing or smelling the food, an example of classical conditioning.
Classical conditioning: association of 2 stimuli
Skinner who believed in operant conditioning (learn to perform behaviour based on consequences of actions) - positive and negative reinforcement.
Experimental approach, but ultimately aim to understand behaviour so it can be controlled –and applied to humans; limited range of species; methodology based on learning: assumes all behaviour is learned.
Approaches to studying animal behaviour:
Comparative Approaches
Comparative Approaches:
We gain insights into behaviour through comparing solutions between groups of species that share common variants on these problems (e.g. ecology, habits, diet).
This approach is especially useful for understanding humans since all our immediate ancestors are extinct, and because behaviour does not fossilised. Comparative approaches are particularly useful in understanding the evolution of humans and our minds.
But we can compare patterns of behaviour among ~490 species of primate:
Bonobos- closest living genetic relative
(separated~5-7mya)
Cousins, NOT ancestors
For example, we can explore tool use and social learning in apes, draw interesting parallels and we can make interesting comparisons with other groups of animals too. A general problem with applying the comparative method to behavior and cognition is getting enough independent comparisons.
Comparative psychology began with Darwin’s claim—profoundly shocking at the time—that humans are similar to other species in mental as well as physical characteristics. this approach can be characterized as anthropocentric because it is concerned primarily with issues related to human psychology.
so why study animal behaviour?
- when using a comparative approach it pays to carefully choose the species that you are comparing to suit the type of question you want to ask.
- We can sometimes ask questions about behaviour in animals that are challenging to ask in humans (e.g. how experiences during development can affect you later on)
- We can’t study behaviour in our direct ancestors (they are extinct) –but we can in our ‘evolutionary cousins’.
- We can learn general principles of behaviour (and its evolution) that apply across groups of animals (including humans).
- We can often test ideas about behaviour in animals that may be challenging to test directly in humans.
Ethology and Behavioural Ecology
Study of animals “being animals”, behaving in their natural environment
Heyday in 1930s-1970s
Focused on core behaviours as “innate”
Ethology (the study of animal behaviour)
interested in patterns of behaviour:
Ritualisation, e.g. swans dancing
Ethology often started with careful observations of natural history, but it went further to formulate hypothesis.
Konrad Lorenz (1903-1989):
He found that those birds would imprint on the first thing they saw:
•Rapid learning
•Independent of the consequences of behaviour
•Sensitive period
Niko Tinbergen (1907-1988) Helped to make the scientific study of animal behaviour part of modern biology. a supernormal stimulus - the concept that an artificial object could be a stronger stimulus for so called instinctive behaviour than an object for with that instinct original evolved.
Karl von Frisch (1886-1982)
waggle dance language of bees
understanding the physiology that drives behaviour
Behaviour Ecology:
- Emerges the mid-1970s onwards
- Strong underpinning in Darwinian theory and modern genetics
- Recognises the variation in behaviour that is affected by situation (ecology, social environment, populations).
- Interested in variation in behaviour, and the fitness consequences of this variation
- (Very similar to ‘sociobiology’ which is no longer used much–it became associated with the naturalistic fallacy: the argument that if something is ‘natural’ it is justified or “good”)
Classical Ethology vs. Behavioural Ecology:
Classical Ethology
Formulation of questions - Inductive: hypotheses follow observation
Methodology- Detailed description and quantification of behaviour
Level of selection - Mostly species or group
Influence of development - Strong
Behavioural Ecology
Formulation of questions - Hypothetico-deductive: Hypotheses sometimes precede observation, sometimes generated by models
Methodology - Performance measurement (fitness), Experimental approach, Molecular tools
Level of selection - Individual, gene
Influence of development - Variable
Behavioural ecology: two challenges
1) Measuring fitness is hard!
What is fitness? (we can also use the term reproductive success)
Capacity of the phenotype that expresses the behaviour in question to produce mature descendants relative to other phenotypes in the same population at the same time.
Phenotype: Any measurable aspect (physical/physiological/behavioural) of an individual that arises from an interaction of the individual’s genes with the environment.
Fitness ‘proxy’: something that can be measured easily, quickly, accurately in order to test model predictions or for use in experiments etc.
- Foraging: energy gain per unit time, gain/risk ratio
- Mate choice: 1/time taken to find suitable partner
- Mate quality: intensity of sexual displays, body size, social status, immune responsivity etc
- reproductive success: number of offspring per breeding event, or per season
2) We don’t know the genetic basis of given behaviours - Behaviours are usually polygenic (influenced by many genes)
- So understanding how they are inherited “as a whole” is challenging
- Plus evolution is about “selfish genes” and propagation of genes that confer particular characteristics: counting offspring is not measuring fitness at the correct level
The ‘phenotypic gambit’ - In behavioural ecology: the gambit is to sacrifice realism for again intractability
We assume for the sake of simplicity only that individual fitness correlates with fitness of the genes responsible for a given behaviour, that behaviour is underpinned by a single gene (with two alleles)
Complex behaviours can be modelled as if controlled by single distinct alleles, representing alternate strategies. (e.g.“genes for behaviour X”).
Take-home and going forward:
- Scientists use approaches of Ethology and Behavioural Ecology
- Fitness is hard to measure –we often use fitness proxies - Gene-level selection is hard to measure -we make heavy use of simplifying assumptions (phenotypic gambit)
Understand that we can make use of the behavioural ecology and evolutionary perspective when thinking about human behaviour, but:
•Comparisons between human and animal behaviour should not be carelessly extrapolated.
•Avoid committing the naturalistic fallacy of assuming that ‘natural’ equates to ‘good’ when thinking about human
Levels of analysis of behaviour - Tinbergen’s 4 questions
‘founding father’ of ethology
Ethologists have asked questions about almost every conceivable aspect of animal behavior—feeding, mating, fighting, and so on. At a broad level, ethologists pose four distinct types of questions.
His 4 questions:
•Mechanism–How does behaviour work? (proximate cause), What stimuli elicit behavior? What sort of neurobiological and hormonal changes occur in response to, or in anticipation of, such stimuli?
•Development–How did behaviour develop during individual’s life? How does developmental variation affect behavior later in life?
•Function–What does behaviour do for survival and reproduction? (ultimate cause)
•Evolution–What is behaviours history? When did a behavior first appear in the evolutionary history of the species under study?
Thousands of studies have been undertaken on each of these four types of questions. Tinbergen’s four questions can be captured in two different kinds of analyses—proximate analysis and ultimate analysis. Proximate analysis focuses on immediate causes, whereas ultimate analysis centers on evolutionary forces that have shaped a trait over time. As such, proximate analysis incorporates Tinbergen’s first two types of questions, and ultimate analysis covers the latter two types.
e.g. Why do Bird's Sing? Mechanism: How is it caused? - ‘Proximate cause’ - ‘mechanism of control’ - Internal or external causes Including: •Brain structure and chemistry •Physiology and hormones •Molecular mechanisms and gene expression •External state of environment
Development: How did it develop in the individual’s lifetime? ‘Ontogeny’ Including: •Learning •Genetic predispositions •Environmental or social factors
Function: What is the value for reproductive success? (i.e. fitness benefit) - ‘Ultimate cause’ - ‘Current utility’ - ‘Adaptive significance’
Evolution:
How did it evolve from ancestors?
Phylogenetic history Including:
•How ancestral species radiated to fill niches
•How competition from other species influenced its evolution
•Cultural evolution
A framework to combat confusion:
e.g. “Is aggression the result of society, the brain or of evolution?”
this question is wrongly putting the different types or levels of explanation against one another.
In this case, understanding the role of society could be asking questions about how aggressive behaviour develops during an individuals life.
understanding the role of the brain is thinking about the internal mechanisms.
understanding the role of evolution could be about function (how aggressive behaviour might help someone survive or reproduce) or about evolutionary history (aggression in our primate ancestors)
all valid questions, just different types of questions we must ask to understand the mechanism, developmental, functional and evolutionary causes of behaviour.
not mutually exclusive.
inform one-another
aids to clarity of thinking
considering all 4 provides a fuller understanding
what was Tinbergen’s experiment for testing the proximate hypothesis on the orientation in bee wolve wasps? (5)
- female bee wolf provisions underground nest with honey bees
- she covers entrance before hunting
- she circles to memorise landmarks near entrance to navigate nest
- set up with pine cones as landmarks and moved them
- female followed centre of pine cones not nest
what was Tinbergen’s experiment for testing the proximate hypothesis on egg shell removal by parent birds? (6)
- removed after the chick hatches
- white inside of the egg may catch predator attention
- artificial gull nests set up with broken eggshell at varying distances from the nest
- closer shells are to gull nests greater the predation
- broken shells increased predation by crows when placed near black headed gull eggs
- supports the idea that removing shells after hatching increases fitness
Conceptual, Theoretical, and Empirical Approaches
Conceptual Approach
Different approaches to ethology. Ethology can be studied from a conceptual, theoretical, or empirical approach: the best studies tend to use all three of these approaches to one degree or another.
Conceptual approaches to ethology involve integrating formerly disparate and unconnected ideas and combining them in new, cohesive ways.
One conceptual breakthrough is W. D. Hamilton’s ideas on kin selection (chapter 9). Kin selection expanded the bounds of classic natural selection models by
demonstrating that natural selection not only favors behaviors that increase the reproductive success of individuals expressing that behavior, but also favors behaviors that increase the reproductive success of those individuals’ close genetic kin. Hamilton’s work has a strong theoretical component to it as well.
Hamilton proposed that fitness is composed of two parts: direct fitness and indirect fitness.
- Direct fitness is measured by the number of viable offspring produced, plus any effects that individual 1 might have on the direct descendants of its own offspring.
- Indirect fitness effects are measured by the increased reproductive success of individual 1’s genetic relative (not including its offspring and any lineal descendants of offspring) that are due to individual 1’s behavior. These actions indirectly get copies of individual 1’s genes into the next generation.
An individual’s inclusive fitness is the sum of its direct and indirect fitness.
For example,
Three vervet monkeys—a mother, her juvenile
offspring, and her older female offspring. Mother helping either daughter would be an example of a direct fitness effect. Siblings helping each other, or helping their mother, would represent indirect fitness effects.
Conceptual, Theoretical, and Empirical Approaches
Theoretical Approach
A theoretical approach to animal behavior often entails the generation of some sort of mathematical model of the world. During the formative years of modern ethology, much theoretical work focused on animal foraging behaviors. One foraging-related question of particular interest was “which food items should an animal add to its diet, and under what conditions?” To tackle this question, a mathematical tool called optimality theory was used (see chapter 11). Optimality theory searches for the best (optimal) solution to a particular problem, given that certain constraints exist in a system.
For example:
Mathematical optimality theory and foraging - Cheetahs can feed on many different prey items, including a gazelle fawn. Ethologists have constructed mathematical models of foraging that determine which potential prey items should be taken. The value
assigned to each prey is a composite of energy value (e), handling time (h), and encounter rate (λ).
Conceptual, Theoretical, and Empirical Approaches
Empirical Approach
Empirical work in ethology can take many forms, but boiled down to one of two types—either observational or experimental studies. Both have been, and continue to be, important to the field of animal behavior.
Observational work involves gathering data on what animals do, without attempting to manipulate or control any ethological or environmental variable.
In order to examine causality, experimentally manipulating the system must be done.
Example:
Observation and experimentation - Imagine your observations led you to predict that red-winged blackbirds will decrease foraging when under predation pressure. However, correlation does not lead to causation. To experimentally examine causality, you could allow a trained falcon to fly over a red-winged blackbird area and observe how its presence affects the amount of foraging.
Sociobiology, Selfish Genes, and Adaptation
The sociobiological notion that genes—in our case, genes associated with behavior—are the units upon which natural selection acts, is often referred to as the “selfish gene” approach to ethology. The phrase “selfish genes” was popularized by Richard Dawkins in 1976. As Dawkins makes clear, genes aren’t “selfish” in any emotional or moral sense. But, genes can sometimes be treated as though they were selfish in that the process of natural selection favors those alleles that increase the expected relative reproductive success of their bearers
We will define adaptations as traits associated with
the highest relative fitness in a given environment.
A summary to the study of evolution and adaptation.
A claim that any character is adaptive can be tested in three ways:
-by modeling, to discover how well the character serves a hypothesized function;
- with the comparative method, to test whether variations in the character across many species are related to variations in ecology;
- and by experiment.
Ideally two or more of these methods can be used
together.
Using the comparative method requires good inferences about the phylogeny of the species being compared. Evolutionary psychologists claim that
understanding how cognitive mechanisms evolved and what they are for can help us to understand how they work. However, testing evolutionary hypotheses about
cognition can be difficult because cognitive processes affect fitness indirectly, through the medium of behavior.
We have encountered three sets of contrasts that seem intuitively to have much in common:
- Mosaic vs. concerted evolution,
- modularity vs. connectedness,
- adaptive specialization vs. general process.
All seem to express a tension between a focus on parts with their specific properties and a focus on a whole with what its parts have in common. In the long (or maybe not so long) run, the kinds of processes they refer to may be linked mechanistically; developmental modularity is already being linked with evolution (West-Eberhard 2003; Schlosser and Wagner 2004).
In any case, the conclusion to be drawn from discussion of each of these contrasts is that the truth is usually a mixture of both. It may be human nature to
focus on only particularities or only wholes, but ‘‘It would be difficult to overemphasize the importance of agility in being able to appreciate both the modularity and the connectedness of biological organization’’ (West-Eberhard 2003, 83).
