Language evolution Flashcards
what are the challenges in studying language
complex cognition, no evidence in fossil record, hard to compare human speech to anything else
what is thought to be the main precursor for language / main trait of language
Referentiality : words stand for things
what is the traditional view of animal communication
communication expresses the signals inter state / affect, now it is known it can also be referential
what is an animal signal
the signal refers to an object and is given in its presence
what are the traits of functionally referential calls in animals
have specific acoustic structure, produced in specific context, elicit a specific response from the listeners
what is the criteria for functional referentiality
there is a signaler who clearly signals the object and meaning of object (production specificity), and a receiver who understands the signal and behaves accordingly (perception specificity)
describe the vervet monkey alarm call system
they have different calls to signal different kinds of predators, each call elicits specific behavioural response
evidence of language learning in chimps
Keith and Cathy Hayes trained chimp to say papa, mama, cup. Chimps have intentional gestures signifying different things (play, food, request care). Chimps trained to learn signs, but not spontaneous use. Chimps used lexigram boards to communicate through visual symbols → learnt to use words in combination and had spontaneous use.
what is the gestural hypothesis and its supporting evidence
language evolved from gestures. Non-human primates use gestures in intentional, referential and flexible ways. Gestures are under great vocabulary control
what are the challenges with the gestural hypothesis
If language started with gestures, why switch? → maybe speech allowed for greater spatial reach and better communication at night, allowing for free hand use. How did the switch occur in the brain?
what is the vocal origin of language
language arose from vocal calls → evidence = alarm system in monkeys and animals songs (complex learnt vocalisations)
what are the neuroanatomical precursors to language
broca’s (language production), wernicke’s (language comprehension), arcuate fasciculus (connects the two)
what kind of area change happened to brocas
greatly expanded in humans, development of mirror neurons (also in homologous area in chimps F5) Area may have evolved to control facial movement in non-human primates and then evolved to control speech in humans
which pathway is more prominent in the arcuate fasciculus in humans
the dorsal pathway (sensory-to-motor) is more prominent and also have more fibres in comparison to chimps, left lateralized!
what is vocal usage learning
ability to control production of pre-existing calls. Ability to learn the appropriate social/ecological contexts in which the call is produce
what is vocal production learning (vocal learning)
the ability to modify acoustic and syntactic structure and/or sounds produced, including imitation and improvisation as a result of experience / interaction with the environment
what is the difference between innate and learnt signals
Innate signals are things we know from birth, often associated with internal affect and emotional aspects (don’t require external auditory input). Learnt is speech and song we learn through experience with environment (required external auditory input and auditory feedback from oneself)
what is the difference between a call and a song
calls are simpler acoustic structure often used to communicate coordination and responses to threat, songs are more complex acoustic structure used for mate attraction or defending territory
how are zebra finches similar to humans in terms of vocal learning
both show evidence of a sensitive period and the need for exposure to environment to learn songs or language → baby birds without tutors will not ever learn their proper song, children experiencing neglect from young age never able to properly learn language
what are the 2 hypothesis about why humans are capable of articulating sounds
it may be due to the position of the larynx (it is positioned much lower compared to other primates), or it could be due to better control resulting from differences in the brain
what is the limbic vocal control pathway
controls voluntary innate emotional vocalisation. Pathway = anterior cingulate cortex → PAG → reticular formation
what is the laryngeal motor cortical pathway
controls learned vocalisations. Pathway = motor cortex → brain stem phonatory nuclei
what is similar about human and bird brains that is not the same in primate brains
the direct connections between the motor cortex and laryngeal nuclei in the brainstem. Birds have direct connection in forebrain and the nuclei which innervate the syrinx
what is the Jungers-Kuypers hypothesis
Direct connections between motor cortex and laryngeal nuclei in the brain stem are only present in humans.
what is the function of the dorso-lateral part of the striatum
: part of the sensorimotor loop, involved in the processing of motor input and output
what is the function of the dorso-medial section of the striatum
it is the associative section, has circuit that go the association cortices projecting from caudal nucleus
how many amino acid changes have occurred to the FOXp2 gene
3 since the human/mouse split and 2 are unique to humans
what do mutations to the FOXp2 gene tells us about its function
mutation associated with heritable speech and language deficits (the Ke family had unintelligible speech, articulatory impairment). May be involved in the interaction between declarative and procedural learning systems. Affects striatum physiology
what abnormalities were found in the KE family
changes in density of brain matter in broca’s, motor area, wernickes, angular gyrus, caudate nucleus, putamen and cerebellum
what happened to songbirds when manipulating the foxp2 gene
limited song learning, reduced plasticity and spine density of the striatum, had fewer dendritic spines associated with plasticity)
how does the basal ganglia work in song learning
Motor—basal ganglia (striatum/area X in birds)—circuit for song learning
