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 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. DEFINITION is a loss of the ability to produce and/or comprehend language

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.