L13 - Behavioral genetics

What behaviors did Galton say showed habitability

• He thought intelligence was habitability - to an extent was correct

• He also thought being a criminal in hereditary so got prisoners and over-layed there faces to come up with averaged face of a prisoner but this is not accurate

What other simple behaviors have a genetic component

• Chemo taxis in E.coli

• Drosphila - if put them on plate on to of a lump of food some will stay on the lump pf food - called sitters and some will go and rome around to find other sources of foo - they are called romers

• both have 2 different genotype: sitter or romer

Genetics of human behavior

• soem behaviours ahve shown a clear egnetic component ;

Fragile X :

• increase in number of CGG repeats, more common in males

Huntingtons:

• associated with increase in CAG repeats, increases in certain pathways over generations

• dominate and neuro-degenrative disorder

Alzhimers:

• build up of beta amaloid plaques in brain - early and late onset

• associated with Chromosome 21 has a gene that codes for Apolipoprotein - involved in digestion of fats

• has 3 alleles

  • E2 - cis, cis

  • E3 -Arg, Arg

  • E4 - Cis , Arg

• with E4 allele by age of 80 all most half of people with it develop Alzheimer’s

• With E3, E2 only 5% develop Alzheimer’s by age of 80

Twin studies

• Jim twins - seperated at birth but still grew up to be very similar

• Have been used to study behavior like schizophrenia :

• Cannabis increases likelihood of it

• MZT : 50% get it , DZT: 1/16, cousins: 1/50

• thought that was due to bad mothering now know has a big genetic component and not due to environment

Autism

• is inability to cope in society

• associated with many traits e.g. poor social behavior, language skills, repetitive behavior (stacking things up)

• many loci involved associated with deletions

• Wise autism →have incredible talents e.g. Stephan Wilster drew St pancreas station 2 years after seeing it , got it all right down to smallest detail

Behavior of animals - mice

• out bread line leave then in an arena with door open

• some mice will be shy and not leave and so stay inside

• where as other mice more confident and leave and go explore the arena

• so have daring mice and shy mice

• If we continue to select and breed shy mice with each other will get mice that are so shy and scared will never go out

Behavior of animals - dog behavior

• dogs are domesticated wolfs

• Pit balls where bed in order to herd cattle, they just and bite their noses in order to get the cattle to do what they want them to do - this is why they are dangerous to humans

• Colidogs herd sheep instead of biting nose bite legs in order to get it to do what it wants

• Pyrenean mountain dogs really dumb and gentle they think they are sheep and so when put with sheep just act like them, good as it scares off wolfs

• Dashshuds → have an inbred genetic disease called narcolepsiy causes them to fall asleep at any point - also in humans

• Basset hound - also have a disease due to inbreeding leading to extreme paranoia - lots of genes are involved poly genetic condition

• Silver foxes → scared of humans , mutant of wild fox with white hair is an example of selection of extreme behavior

• if has wild type population of silver foxes if select the friendliest foxes - the ones that interact with humans can produce domesticated foxes

• have dominate white spotting → less melanin produced → less aggressive