Monogamy, Polygyny,
Polyandry
Kelly D. Parungao
PSYC 141
April 07, 2011
Mating Systems



Monogamy - 1 male
to 1 female
Polygyny - male
mating with more
than 1 female
Polyandry - female
mating with more
than 1 male
Monogamy
When only a single
parent is not enough to
raise offspring, both
parents are necessary.
 Example of species in
Monogamy:

– Birds (Doves, Albatross)
– Fish (Cichlid Fish)
– Monkeys (Golden Lion
Tamarins)
Albatross




Will remain faithful to
one another for life.
Baby birds cannot fly
and due to this, both
parents are needed.
One bird will protect the
nest while the other
retrieves food.
Essential for birds to be
monogamous.
When Life Gets Easier


In certain species, when
life gets easier, one
leaves. But who?
Based on three factors:
– 1. Internal or External
Fertilization
– 2. Who has more to gain?
– 3. Who is more depleted?
Polygyny

Lions - exists as a pride
– One male will be dominant in
the pride, and be in charge
for about 1 - 3 years
– When males fight for
dominance, if one is evicted
from dominance position, the
newly arrived male will kill
the cubs of the previous
males.
– Males protect pride from
hyenas.
Polyandry

Sandpiper Birds
(arctic)
– Making eggs is
easy due to the
abundance of food.
– Males become
protectors of eggs.
Polyandry

Acorn Woodpecker
– Acorns need to be
stored, and so these
woodpeckers create
deep holes in the trees
and store them within.
– Each hole is specific for
each acorn, this is a
hard job to collect and
store, so a
monogamous pair is not
enough.
– Correlation between #
alive clutch to # of
parents.
Polyandry is necessary for
this species for both male
and female fitness to be
optimal.
BUT WHY?
“Monogamy unnatural for our sexy
species” Christopher Ryan



Proposes that
monogamy is not
natural.
“Fierce Egalitarianism” in
hunter-gather societies.
When we started to
settle in communities,
there was a bigger need
to know who owned
what.
Turning Towards Monogamy


10th Commandment:
“Thou shalt not covet
thy neighbor’s house,
thou shalt not covet thy
neighbor’s wife, ….”
Not until we got into
agriculture were we
able to have wealth be
kept in the family. Thus
paternity became a
concern.
Primate Species


The two species that
we are closest to are
chimpanzees and
bonobos.
Both sexually active
with one another, in a
non - monogamous
society.
QuickTime™ and a
decompressor
are needed to see this picture.
Human Body
Large male testicles.
 Male sex organs outside of body to
regulate a cool temperature.
 Males reach orgasm before women.
 Women’s breasts, vocals and multiple
orgasms.

Not Natural
We choose to live a life of monogamy
and that does not make us naturally
monogamous.
 A life choice.
 What’s your opinion? Are humans
naturally monogamous?

Questions
What are your thoughts on altruism and
its relation to monogamy? Could it be
that we care more for that one
individual, causing us to only want to
support and be with the other? And vice
versa?
 What are your thoughts on arranged
marriages? Is it a successful mating
system?

Sources
Evolutionary Analysis, 4th Edition Freeman
 Monogamy unnatural for our sexy
species http://www.cnn.com/2010/OPINION/07/
27/ryan.promiscuity.normal/index.html
