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

“r” - Turtles lay & abandon many eggs

“K” - Chimps care for offspring for 5-7 years

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 BrainWernicke’s Area• Receives speech from primary auditory area and decodes

speechBroca’s Area• develops speech and sends it to the motor cortexGeschwind’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

DEFINITIONis 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.