Biology of Human Behaviour
Lecture 1: Riedstra – Lateraliza2on of human behaviour
Lateraliza*on → behavioural asymmetry.
Black box model → behavioural input received by sensory systems, transferred/translated
in black box/brain, output to adapted behaviour. Two hemispheres differ in func*on and
structure.
Corpus callosum → bundle of fiber exchanging signals from one hemisphere to the other.
Le3 hemisphere → symbols, right visual field, logic.
- Sensory s*mulus from right side of the body
- Motor control of right side of the body
- Speech, language, and comprehension
- Analysis and calcula*ons
- Time and sequencing
- Recogni*on of words, leHers, and numbers
Right hemisphere → emo*ons non-verbal, leI visual field.
- Sensory s*mulus from le( side of the body
- Motor control of le( side of the body
- Crea*vity
- Special ability
- Context/percep*on
- Recogni*on of faces, places and objects
Motor laterality → cross-over
- Emo<onal expression starts on le3 size of the face as emo<ons happen right.
- Facial expressions more pronounced in leI.
- Language in one hemisphere for specializa*on, more precise func*oning. - Other
brain func*ons migrate for more space along with specializa*on
Three condi*ons for evolu<on → change in the inherited characteris*cs of biological
popula*ons over successive genera*ons.
1. Heredity → DNA/RNA, genes
2. Variability → mutaLons, recombinaLon, gene flow
3. Selec<on → natural/sexual selecLon, driO
Side preference in birds, light can manipulate lateraliza*on of birds (egg). Lateraliza*on
widespread in animal kingdom, therefore must have benefits?
• Benefits/advantages → Avoidance hemispheric conflict, increased capacity
through specializa*on, increased speed (avoid cc), parallel processing (mul*tasking)
→ Increased cogni*on?
, • Cost/disadvantage → predictability, damage, loss of func*on, mismatch with
popula*on bias
Differences in strength and direc<on lateraliza<on. Strength is devia*on from chance.
Lateraliza*on at individual level → makes beHer/more efficient forager, biologically
relevant, beHer survival, produce more offspring and ‘beHer’ offspring. LH less lateralized.
Correla*on between lateraliza*on and cogni*on.
Dual tasking → using two tasks in different hemispheres. Chicks incubated at light
become lateralized for food discrimina*on and predator recogni*on.
Testosterone decreases speed of growth of leI hemisphere, and size corpus callosum. First
reduces lateraliza*on, second increases.
Measurement for dual task with func<onal transcranial doppler, measures blood
flow/ac*vity.
Handedness determined by parents, perinatal stress increases chance on sinistral,
male/testosterone higher chance sinistral, iden*cal twins can mirror and cradling posi*on.
Handedness heritable but not mendalian, reason for polymorphism.
Expecta*ons: dual task
• Stronger lateraliza*on associa*on with beHer task performance in single- and dual
task condi*ons.
• Two task performed simultaneously: performance beHer when tasks are located
contralaterally instead of ipsilaterally.
• Typical lateraliza*on of func*on results in beHer task performance in single- and dual
task condi*ons.
Handedness → heritable, but mendalian right
= 90%, leI = 10%.
Evolu*on handedness measure by environment where evolu*on took place.
Complexi*es → direc*on/strength intertwined, preference or skill (weak correla*on),
focus western society.
LeI-handed nega*ve frequency dependent selec*on. LeI human benefit during fight,
increases survival and social dominance. This affects reproduc*ve success. LH high in combat
sports. Indirect evidence for LH advantage, associa*on between LH propor*on and
aggression in pre-industrial socie*es.
Lecture 2: van de Berg - Evolu2on of social behaviour and Cultural Evolu2on
Social behaviour → behaviour that has fitness consequenses for both the individual that
performs the behaviours (actor), and at least one other individual (recipient) The ini*al
condi*ons will indicate which social behaviour will eventually fixate in the popula*on
, Coordina<on → most common type at the start is fixated
Evasion → results in polymorphic popula*on with an interal equilibrium (regardless of the
star*ng condi*ons
Altruism → common interest, individual interest
Cultural diversity → generated through *me by processes of descent with modifica*on, like
species diversity
Lecture 1: Riedstra – Lateraliza2on of human behaviour
Lateraliza*on → behavioural asymmetry.
Black box model → behavioural input received by sensory systems, transferred/translated
in black box/brain, output to adapted behaviour. Two hemispheres differ in func*on and
structure.
Corpus callosum → bundle of fiber exchanging signals from one hemisphere to the other.
Le3 hemisphere → symbols, right visual field, logic.
- Sensory s*mulus from right side of the body
- Motor control of right side of the body
- Speech, language, and comprehension
- Analysis and calcula*ons
- Time and sequencing
- Recogni*on of words, leHers, and numbers
Right hemisphere → emo*ons non-verbal, leI visual field.
- Sensory s*mulus from le( side of the body
- Motor control of le( side of the body
- Crea*vity
- Special ability
- Context/percep*on
- Recogni*on of faces, places and objects
Motor laterality → cross-over
- Emo<onal expression starts on le3 size of the face as emo<ons happen right.
- Facial expressions more pronounced in leI.
- Language in one hemisphere for specializa*on, more precise func*oning. - Other
brain func*ons migrate for more space along with specializa*on
Three condi*ons for evolu<on → change in the inherited characteris*cs of biological
popula*ons over successive genera*ons.
1. Heredity → DNA/RNA, genes
2. Variability → mutaLons, recombinaLon, gene flow
3. Selec<on → natural/sexual selecLon, driO
Side preference in birds, light can manipulate lateraliza*on of birds (egg). Lateraliza*on
widespread in animal kingdom, therefore must have benefits?
• Benefits/advantages → Avoidance hemispheric conflict, increased capacity
through specializa*on, increased speed (avoid cc), parallel processing (mul*tasking)
→ Increased cogni*on?
, • Cost/disadvantage → predictability, damage, loss of func*on, mismatch with
popula*on bias
Differences in strength and direc<on lateraliza<on. Strength is devia*on from chance.
Lateraliza*on at individual level → makes beHer/more efficient forager, biologically
relevant, beHer survival, produce more offspring and ‘beHer’ offspring. LH less lateralized.
Correla*on between lateraliza*on and cogni*on.
Dual tasking → using two tasks in different hemispheres. Chicks incubated at light
become lateralized for food discrimina*on and predator recogni*on.
Testosterone decreases speed of growth of leI hemisphere, and size corpus callosum. First
reduces lateraliza*on, second increases.
Measurement for dual task with func<onal transcranial doppler, measures blood
flow/ac*vity.
Handedness determined by parents, perinatal stress increases chance on sinistral,
male/testosterone higher chance sinistral, iden*cal twins can mirror and cradling posi*on.
Handedness heritable but not mendalian, reason for polymorphism.
Expecta*ons: dual task
• Stronger lateraliza*on associa*on with beHer task performance in single- and dual
task condi*ons.
• Two task performed simultaneously: performance beHer when tasks are located
contralaterally instead of ipsilaterally.
• Typical lateraliza*on of func*on results in beHer task performance in single- and dual
task condi*ons.
Handedness → heritable, but mendalian right
= 90%, leI = 10%.
Evolu*on handedness measure by environment where evolu*on took place.
Complexi*es → direc*on/strength intertwined, preference or skill (weak correla*on),
focus western society.
LeI-handed nega*ve frequency dependent selec*on. LeI human benefit during fight,
increases survival and social dominance. This affects reproduc*ve success. LH high in combat
sports. Indirect evidence for LH advantage, associa*on between LH propor*on and
aggression in pre-industrial socie*es.
Lecture 2: van de Berg - Evolu2on of social behaviour and Cultural Evolu2on
Social behaviour → behaviour that has fitness consequenses for both the individual that
performs the behaviours (actor), and at least one other individual (recipient) The ini*al
condi*ons will indicate which social behaviour will eventually fixate in the popula*on
, Coordina<on → most common type at the start is fixated
Evasion → results in polymorphic popula*on with an interal equilibrium (regardless of the
star*ng condi*ons
Altruism → common interest, individual interest
Cultural diversity → generated through *me by processes of descent with modifica*on, like
species diversity
