Lecture 22: Human and animal Flashcards Preview

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How did Darwin define communication in 1872?
What was the problem with this definition?

He said it was the expression of emotions in man and animals.
It doesn't focus on the communication itself, or cognition, it just focuses on the mind, emotion and feelings that are expressed via behaviour.


Do we know that communicate?

We communicate intentionally, however this is hard to study and it isn't important to study.


Define communication

When actors use specially designed signals or displays to modify the behaviour of reactors. Ecologists are concerned with how and why these signals evolved to make them specialised.


What are the three main questions about communicative behaviours?

Why have the signals evolved?
What function do they serve?
How have they evolved?


Describe some constraints that can cause the specialisation of certain behaviours

Ecological constraints; it constrains which modalities, aka types of signals, are useful. This can affect auditory, olfactory, visual and tactile signals because of energy, location, obstacles etc. This was found by Alcock 1984. The signal type depends on need and function in relation to ecology.
Receiver constraints; The sense of the receiver can also constrain the evolution. Signals evolve from existing behaviour, aka receiver senses. If receivers respond to behaviour before it happens, they will be favoured by evolution, this can happen with intention movements.


Describe the communication for ants that were specifically created via ecological constraints

Also called leptothorax. They feed on large dead beetles that require 2 ants to carry. The ant that finds the beetle, goes to the nest, regurgitates and produces a chemical signal. They then lead the helper to the site via tandem (antennae resting on the other ant's abdomen), this is tactile.
Fire ants feed on mobile prey, to get the other ants to carry the prey, they release a chemical scent trail that disperses quickly so the ants must follow promptly.
Leaf cutter ants have permanent patches of food, long lasting chemical scents and visual paths through vegetation.


What ecological constraints did Waser and Waser 1977 find in grey cheeked mangabeys?

They whoop-gobble between groups and scream within the group. They're the same volume but the whoop-gobble is deeper so it travels further, this is because they live in dense woodland so evolution selected the pitch that travelled furthest.


Discuss communicative behaviours shaped by receiver constraints in primates
What about displacement activities?
What about ritualisation?

A silent-bared teeth display. It's a ritualised intention movement that is a reaction to aversive substances, it's also a signal of submission or affiliation, Hooff 1973.
Tinbergen 1952 found that fish showed displacement activities during courtship, threat displays and territorial behaviour. It involves zig zagging behaviours.
Humans also have this, it's produced by the ANS and it involves blushing, urination, sweating etc. It can also indicate stress, like scratching. It could be associated with a conflict between motivations.
It involves intention movements or displacement activities that become highly stereotyped, repetitive, exaggerated and augmented by physical changes like plumage, they improve the signal function of a display.


What are the three hypotheses about ritualisation?

Reduction of ambiguity


Describe the reduction of ambiguity hypothesis

Ritualised signals are less ambiguous and more clear. For example tree frogs have species specific calls for species recognition. However, the increased clarity can reduce the information shared about the motivation of the actor, but this can be good.


Describe the manipulation hypothesis

The signals are beneficial to the signaller, this creates an evolutionary arms race between the actor and the receiver. The actor manipulates the receiver's senses via ritualisation and the receiver evolves strategies to avoid this. This could mean that the signals get louder, or cooperative signals are quieter.


Describe the honesty hypothesis

This involves Zahavi's handicap hypothesis. The ritualisation allows the signals to becomes reliable and show quality. Honest signals are the only ones that will prevail, the others will die out via sexual selection. An example of this is stotting, developed by Fitzgibbon in 1988. Stotting is better in the wet season.


Does communication need complex cognitions?

No but it can involve cognition. For example, Cheney found this in 1990 with vervet alarm calls. Slocombe 2005 found that chimps give different calls depending on the type of food. Furthermore, social bonding is associated with increased communication. Also, group size is related to the growth of relative brain size, Dunbar 1996.


Can animals intentionally deceive others?

Tanner 1993 found that gorillas hide their play faces.


How is language different from animal communication?

It's intentional, complex and productive. It can change the way we think about things and they form a core of human culture.


Why did language evolve?

Traditional theories believe in information exchange about the environment (tools), for example, Pinker.
However, new theories believe in the social aspect. For example, Dunbar 1996, he believed that it's important for the exchange of social information. People talk about social things, hunting doesn't require language, tool construction is easiest by demonstration and brain size doesn't correlate to complex tool use. It evolved to support cohesion