Genes and Behavior Genes and Behavior Cog. Sci. 1 Cog. Sci. 1 - PowerPoint PPT Presentation

Genes and Behavior Genes and Behavior Cog. Sci. 1 Cog. Sci. 1 Ralph Greenspan Ralph Greenspan rgreenspan@ucsd.edu rgreenspan@ucsd.edu

“It’s genetic. My father was a dog, and I’m a dog.”

Mendel Galton

Mendelian inheritance discrete variation – single gene differences

23 pairs of chromosomes

Galtonian inheritance continuous variation – multiple gene differences

Galtonian inheritance continuous variation – multiple gene differences most human traits

Macmillan's Magazine (1865) vol. 12 pp. 157-166

Prior to concepts of culture, sociology, psychology

How to reconcile Mendel and Galton?

Each of the many small-effect Each of the many small-effect genes seen in continuously genes seen in continuously varying traits are inherited varying traits are inherited as single Mendelian genes. as single Mendelian genes. No single one makes much difference. No single one makes much difference.

But small-effect genes are hard But small-effect genes are hard to detect and identify to detect and identify (because their individual effects are small) (because their individual effects are small)

Twin Studies Twin Studies to get an idea of relative genetic contribution to get an idea of relative genetic contribution

Separated at birth, the Malfert twins meet accidentally. Separated at birth, the Malfert twins meet accidentally.

Genetic Similarity Relationship Identical twins reared together 100% Identical twins reared apart 100% Fraternal twins reared together 50% Siblings reared together 50% Siblings reared apart 50% Biological parent & child, lived together 50% Biological parent & child, lived apart 50% Adoptive parent & child, lived together 0% Adopted siblings, reared together 0%

Twin Correlations Raised apart Raised together

Cloning – – twins across a generation twins across a generation Cloning

Sometimes you can detect single gene (Mendelian) inheritance in humans when you take into consideration and control for non-genetic factors.

Genes do not “ “encode encode” ” behavior, behavior, Genes do not they encode proteins. they encode proteins.

How do genes affect behavior? How do genes affect behavior? • The brain is made up of neurons. All information • The brain is made up of neurons. All information processing takes place within neurons. processing takes place within neurons. – – Therefore, behavior is a product of neuronal activity. Therefore, behavior is a product of neuronal activity.

How do genes affect behavior? How do genes affect behavior? • The brain is made up of neurons. All information • The brain is made up of neurons. All information processing takes place within neurons. processing takes place within neurons. – Therefore, behavior is a product of neuronal activity. – Therefore, behavior is a product of neuronal activity. • The parts/activity of neurons that are important in • The parts/activity of neurons that are important in behavior are made up of proteins or are the result of the behavior are made up of proteins or are the result of the activity of proteins. activity of proteins.

How do genes affect behavior? How do genes affect behavior? • The brain is made up of neurons. All information • The brain is made up of neurons. All information processing takes place within neurons. processing takes place within neurons. – – Therefore, behavior is a product of neuronal activity. Therefore, behavior is a product of neuronal activity. • The parts/activity of neurons that are important in • The parts/activity of neurons that are important in behavior are made up of proteins or are the result of the behavior are made up of proteins or are the result of the activity of proteins. activity of proteins. • Genes encode these proteins • Genes encode these proteins

How do genes affect behavior? How do genes affect behavior? • The brain is made up of neurons. All information • The brain is made up of neurons. All information processing takes place within neurons. processing takes place within neurons. – – Therefore, behavior is a product of neuronal activity. Therefore, behavior is a product of neuronal activity. • The parts/activity of neurons that are important in • The parts/activity of neurons that are important in behavior are made up of proteins or are the result of the behavior are made up of proteins or are the result of the activity of proteins. activity of proteins. • Genes encode these proteins • Genes encode these proteins • Thus, to fully understand the biological basis for behavior • Thus, to fully understand the biological basis for behavior we need to understand the sorts of things genes do, how we need to understand the sorts of things genes do, how they affect the brain, and how the brain produces they affect the brain, and how the brain produces behavior. behavior.

Mendelian

Mendelian

MAO-A degrades neuromodulators dopamine, serotonin, and norepinephrine

Low MAO-A results in more neuromodulator; each stimulus is stronger.

MAO-A variants

MAO-A variants (low) (low)

(low) (high) relatively common

Development of antisocial behavior in adults low high

Prairie vole Montane vole

Prairie vole Montane vole Mating system monogamous promiscuous

Prairie vole Montane vole Mating system monogamous promiscuous Parental care biparental maternal

Prairie vole Montane vole Mating system monogamous promiscuous Parental care biparental maternal Partner preference high low

Prairie vole Montane vole Mating system monogamous promiscuous Parental care biparental maternal Partner preference high low Selective aggression high low

(AVP) (Avpr1a)

Avpr1a receptor pattern Montane Prairie (monogamous)

Avpr1a receptor Effect of pattern vasopressin Montane Prairie (monogamous)

Avpr1a receptor gene structure (monogamous)

Transgenic mouse Prairie vole (monogamous)

Transgenic mouse Prairie vole

A microsatellite “for” monogamy?

Avpr1a microsatellite polymorphisms among Prairie voles microsatellite length

Avpr1a microsatellite polymorphisms among Prairie voles microsatellite length

…but it’s more complex (as usual) microsatellite present microsatellite absent genetic polygamy (paternity) montane vole genetic monogamy (paternity) behavioral polygamy behavioral monogamy prairie vole

…but it’s more complex (as usual) microsatellite present microsatellite absent genetic polygamy (paternity) montane vole genetic monogamy (paternity) behavioral polygamy behavioral monogamy exceptions in both directions: prairie vole microsatellite monogamy = / = prairie voles can be polygamous

“Model” organisms

Aggression in the fruit fly Drosophila

Selective breeding for aggression * * % arena’s with fights

Intensity of fighting # of roll overs * *

80 genes of all sorts

Gene Function Aggr/Neu Gene Function Aggr/Neu Cam synapse 1.161 Snap synapse 1.438 trpl synapse 1.115 Obp56a olfaction 0.4 vri rhythms 0.805 TpnC41C muscle 1.432 Cyp6a20 olfaction 0.683 Mlc1 muscle 1.373 Est1 metabolism 1.34 Chit metabolism 1.165 Pif1 development 0.809 Est8 metabolism 1.534 wun development 1.119 Treh metabolism 1.349 DppIII development 0.882 Drs immunity 2.082 kek4 development 0.721 GNBP1 immunity 0.619 Lk6 development 0.81 Dh immunity 0.615 developme mub development 0.774 CAP nt 1.2 mfas development 1.305 Snap synapse 1.438

) ) Gene Function Aggr/Neu Gene Function Aggr/Neu . . e e c c n n Cam synapse 1.161 Snap synapse 1.438 e e r r e e trpl synapse 1.115 Obp56a olfaction 0.4 f f f f i i Galtonian Galtonian d d vri rhythms 0.805 TpnC41C muscle 1.432 h h c c Cyp6a20 olfaction 0.683 Mlc1 muscle 1.373 u u m m Est1 metabolism 1.34 Chit metabolism 1.165 s s e e Pif1 development 0.809 Est8 metabolism 1.534 k k a a m m wun development 1.119 Treh metabolism 1.349 e e n n DppIII development 0.882 Drs immunity 2.082 o o e e kek4 development 0.721 GNBP1 immunity 0.619 l l g g n n Lk6 development 0.81 Dh immunity 0.615 i i s s developme o o mub development 0.774 CAP nt 1.2 n n ( ( mfas development 1.305 Snap synapse 1.438