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Lecture 6

ANTHROP 3HI3 Lecture Notes - Lecture 6: Alarm, Group Selection, Natural Selection

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Priscilla Medeiros

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Chapter 1
1. What role does consciousness have in governing altruistic behavior?
In Chapter 1, Dawkins states that his definition of selfishness and altruism are
behavioral and do not concern conscious or unconscious motives
He does comment that in human society, we can consciously override our
genetically encoded selfishness through social learning
2. Why are alarm calls altruistic?
Definition of altruism: An entity is said to be altruistic if it behaves in such a way
as to irease aother suh etits elfare at the epese of its o
Welfare is defied as haes of surial, ee if the effet o atual
chances of survival SEEMS negligible
So, what is important is whether the effect of an act is to lower or raise
survival prospects of the presumed altruists and beneficiary
Ma sall irds, he the see a predator, gie a alar all, upo
which the whole flock takes evasive action
There is indirect evidence that the bird who gives the alarm call puts itself
i dager eause it attrats the predators attetio
This is only a slight additional risk, but seems to qualify as an altruistic act
by our definition
3. What is wrong with the argument that traits evolve for the good of the group or the
An erroneous explanation for altruism that is that living creatures evolve to do
thigs for the good of the group
Perpetuation of the species is a consequence of reproduction, so the
futio of reprodutio is to perpetuate the species
Evolution works by natural selection, and natural selection means
differetial surial of the fittest
Basically, a species has a better chance of survival if individual members
are prepared to sacrifice themselves for the good of the group
The problem with this argument is that even in a group of altruists, there will be
a small minority who are selfish; if there is even one selfish rebel, they can
eploit the altruists ehaior ad selfish idiiduals are ore likel to surie
and have children
Eah of the hildre ill hae the selfish reels traits - after many generations,
the altruisti group ill e oerru  selfish idiiduals
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Selfish individuals can also migrate into a group from neighboring groups and
through inter-marriage
So, eventually, there will be no evolution of traits FOR THE GOOD OF THE GROUP
because there will be too many selfish individuals
4. What is individual selection?
Dawkins calls individual selection, GENE selection
Individual selection: Even in a group of altruists, there will almost certainly be a
dissenting minority who refuse to make any sacrifice
If there is just one selfish rebel, prepared to exploit the altruism of the rest, then
he, by definition, is more likely than they are to survive and have children
The individual-selectionist believes that groups do die out, and whether or not a
group dies out is determined by the behavior of the individuals within the group
He might even admit that IF ONLY individuals in a group had the gift of
foresight, they could see in the long run that their own best interests lay
in restraining their selfish greed, to prevent the destruction of the whole
5. Does evolution work more rapidly between competing groups or between
competing individuals?
Group extinction is a slow process compared to individual competition, so even
in the long-term process of group extinction, selfish individuals will prosper in
the long term
That is, a group of altruistic individuals will take longer to be overrun by selfish
individuals, than the lineage of a selfish individual to progress
6. What is a unit of selection and what is the main one? Why is this important?
A uit of seletio is…
The fundamental unit of selection, and of self-interest, is the GENE, the unit of
A gene is defined as any portion of chromosomal material that potentially
lasts for enough generations to serve as a unit of natural selection; it is a
replicator with high copying-fidelity
A gene is also a genetic unit that is small enough to last for a large
number of generations and to be distributed in the form of many copies
The more likely a length of chromosome is to be split by crossing-
over or altered by mutations, the less likely it is to qualify as a
This is iportat eause…
7. What is group selection? added this oe i eause its proal good to ko
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Basically, the theory of group selection says that a group (species) has a better
chance of survival if individual members are prepared to sacrifice themselves for
the good of the group, rather tha a group i hih eeroe has selfish
As a result, groups consisting of self-sacrificing individuals populate the world
Deeply ingrained in people, schools, etc. as a good evolutionary idea, but now is
not heavily endorsed by biologists
This theory has moral and political appeal - we may behave selfishly as
individuals, but we do honor and admire those who put the welfare of others
Young men are expected to die as individuals for the welfare of the
country as a whole
The leaping of gazelles in front of a predator is similar to bird alarm calls,
arig opaios of dager hile allig the predators attetio to
the stotter himself
Selfish behavior has the opposite effect of altruism - an entity is said to be
altruisti if it ehaes i suh a a to irease aother suh etits elfare at
the expense of its own; a selfish individual is one that behaves in a way to
increase his/her own welfare at the epese of aother etits ell-being
Nest in large colonies; nests only a few feet apart
When the chicks hatch, they are small and easy to swallow
It is oo for a gull to eat its eighors hiks - obtains a good
meal without having to leave its own nest unprotected
Mantises will attack almost anything
When a male and female mate, the male mounts the female and
copulates; often, the female will eat the male by biting his head
off, either as the male is approaching, or immediately after he
mounts, or after they separate
The loss of the ales head does ot thro hi off his seual
stride - the insect head is the site of some inhibitory nerve
eters, so its possile that the feale iproes the ales
sexual performance by eating his head (this is an added benefit, in
addition to the fact that she gets a good meal)
Have been seen standing on the edge of the water, hesitating
before diving in, because of the danger of being eaten by seals
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