Transcript Body Size, Brains and Stuff

The Biology and Origins
of Language
Part 1
Body Size, Brains and Stuff
Smaller Body Size
• Short lifespan
• R selected
• Brain functions
integrated
• Reliance on instinct
• Stimulus bound
learning
• Rigid response to
environment
• Less adaptable to
change
• Short neurons lead
to short reaction
time
Larger Body Size
• Long lifespan (for
learning)
• K selected
• Brain functions
specialized
• Reliance on learning
• Transferable learning
• Flexible response to
environment
• More adaptable to
change
• Long neurons lead to
delayed reaction time
r and K selection
“K” - Chimps care for
offspring for 5-7 years
“r” - Turtles lay &
abandon many eggs
Animal vs. Human Brains
• Animals have much less
cortex (gray matter)
and much shorter
nerve fibers than
humans.
• The Cortex is where
higher brain functions
like thinking take
place.
• The non-cortical brain
is involved in reflexes
and emotional
reactions.
Brain to Body Ratio
Brain Specialization
Of all
animals,
only
humans
and apes
have been
found to
have
lateralized
brains
Language Parts of the Brain
Wernicke’s Area
• Receives speech from primary auditory area and decodes
speech
Broca’s Area
• develops speech and sends it to the motor cortex
Geschwind’s Territory
• at the junction of the auditory, visual, and somatosensory
cortexes
• neurons in this lobule can process different kinds of stimuli
(auditory, visual, sensorimotor, etc.) simultaneously.
• doesn’t fully develop until about five years of age
• classifying, labeling, thinking abstractly, forming concepts.
Arcuate fasiculus
• Bundle of neurological connections between three areas
Left Cortex Language Areas
Inferior parietal lobule AKA
Geschwind’s Territory
Aphasia
DEFINITION
is a loss of the
ability to
produce
and/or
comprehend
language
Two forms of Aphasia:
GRAMMAR PROBLEMS
Damage to Broca’s Area
results in the inability to
complete grammatically
complete sentences.
PROBLEMS IN MEANING
Damage to Wernieke’s Area
results in speech that has a
natural-sounding rhythm
and normal grammatical
patterns but is meaningless.
How do we know what parts
of the Human Brain
Control Language?
Videos on Damage to
Human Brains
Physical Injury
Stroke Patients
Language Activity Brain Scans
Genes and Language
Two links between specific genes and
language:
1. The FoxP2 Gene
2. ASPM and Microcephalin Genes
FoxP2
• Discovered through one family(the
“KE” family), half of whom had a
defect in that gene and could not
speak
• The KE family was of Pakistani origin
living in Britain
• In 37 members in 4 generations, 15
suffered specific language
impairment
FoxP2
• Patterns of inheritance indicated
standard dominant/recessive
inheritance, not sex chromosome
inheritance.
• Fox P2n is Located on a short segment
of chromosome 7
• each of us inherits two copies of the
FOXP2 gene: one from our mother,
and one from our father
• both copies must be intact for our
language functions to be normal.
FoxP2
• responsible for producing a protein
called a transcription factor.
• transcription factors bind to DNA
molecules to turn other genes off and
on.
• Broca’s area and the caudate nuclei
(regulates motor control) are
smaller than in normal people
• trouble in identifying some
elementary sounds of language,
• trouble in understanding sentences
and using grammar
ASPM and Microcephalin
• These genes are associated with increased
brain size
• Mutations at these sites cause primary
microcephaly, a developmental defect with
severe reduction in the cerebral cortex—
(planning, abstract reasoning and other
higher brain functions).
• Microcephalin was more involved in
evolution of primate brain size (prosimians
to monkeys)
• ASPM more involved in late evolutionary
step leading to humans.
ASPM and Microcephalin
Both genes are thought to affect
brain development.
Older versions of these genes are
found in tonal language
populations. (Half of the world’s
language are tonal including
many in Asia, Southeast Asia
and Sub Saharan Africa).
New versions of these genes are
found in non-tonal language
populations.