Greg Detre
30/5/01
MS Dawkins
pregnancy blocking � stud males very sensitive to other males� kids
if female reabsorbs the embryos, cuts her losses
penguins � males �, females fish � have to find their own way back
sticklebacks
seahorses � male gets pregnant
males are haploid � unfertilised eggs
females diploid � fertilised eggs
if queen bee chooses to let eggs be fertilised � females
all sperm from given male are identical
diploid � pairs of chromosomes aren't identical
females are more closely related to their sisters (75%) than own offspring (50%)
some females �/span> sterile workers, others � queens (number/group varies with species)
termites � different haploid/diploid genetics (but very inbred)
same with maked(???) mole rats
but Damaraland � why kin groups
Hamilton�s original equation
degree of relatedness
balance of cost/benefit
degree of certainty
mole-rats need to be in a group to survive
so might as well be in a group of kin
Jains: showed eusociality (some individuals never reproduce, castes)
human are slightly eusocial � eunuchs???
flexible, not fixed
we�re more like birds � young stay behind for c. 1 year, then leave
if rare gene for being nice to children
the nice-parent gene will eventually proliferate
green beard altruism-to-this-gene would be best
a green beard gene needs to be a dual-function single gene
if >1 gene, then you�d get deception
what is a gene???� for AB:
�a functional unit, e.g. gene for � maternal care, extra dose of hormone
could encompass many nucleotide bases
variable length of chromosome that �/span> identifiable difference phenotypically
probably 1 nucleotide stays within a single sequence
wouldn't expect sibling care unless you had a much older sibling looking after you
Hamilton equation � benefits, as well as certainty
there needs to be a benefit/role for the sibling to add
are most social animals genetically similar/kin-based???
many animals are careful to breed outside the groups, e.g. young male elephants get kicked out, female birds, chimps
to avoid in-breeding (e.g. negative imprinting in humans)
in-breeding vs the survival value of groups
genetic similarity vs selfish group advantage
either one sex disperses, or incest taboo of some sort
or be so inbred that there�s no lethal recessive genes left (e.g. naked mole-rats, lab rats)
anti-greenbeard argument
genetic outlaws � the rest of the genome loses out because the greenbeard gene benefits at the expense of the genome (e.g. helping a non-relative with a green beard at the expensive of overall genetic similarity)
so the rest of the genome would suppress it
MHC � so concerned with immune system + disease
Hamilton thought that the whole of disease is explained by sexual reproduction
disease can mutate so much faster than a larger organism
so � promiscuity than originally thought (in humans somewhere between 4-40%)
maybe babies have evolved to look uniform
birds are much less monogamous than thought (Tim Birkhead) � social not sexual monogamy, even in females
variation is one reason
why aren't more genes contributed > 2 genders
blue-haired ras(???) � can be fertilised by > 1 male at one time
spiders � store sperm from >1 male in pockets
trade-off between promiscuity and male caring for children
current consensus re MHC
tendency to prefer genetically-different individuals (in humans) � children resistant to wide range of diseases
women on the pill seem to lose the ability to discriminate on the base of MHC (Wedekind)
which sweat most pleasant???
on-the-pill random, pill better at chosen
base pair
why don't you get free-rider greenbeards???
look for evidence of altruism � cheat-proof
social behaviour = a sort of greenbeard
you group together with other social animals
what if evolved a nestling with a big mouth???
= a greenbeard = a differential effect by genotype, would �/span> lots of big-mouths