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Mammalian Reproductive Strategies
Prototheria (monotremes)
Metatheria (marsupials)
Eutheria (placentals)
Patterns of Social Behavior
Sociability: important characteristic for
most primates
Continuous interactions among a group
of individuals
Advantages of Group Living
• 1. Observational learning.
– Reduces necessity of individual trial-anderror learning.
• 2. Possibile genetic resistance to disease
and parasites.
• 3. Efficient location of food resources
• 4. Increases the reproductive fitness of
group members.
Social groupings
What kind of social grouping?
Polygyny: one reproductively mature (RM) male, several RM females
Gelada baboon
Lip retraction: threat display
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Individuals are solitary
Males are intolerant of one another.
Single male establishes a large territory.
Contains several females
Each female has her own separate home range
• Polygyny
• Extensive home ranges
Multi-male; multi-female
groups
Overlapping territories
• Multi-male, multi-female groups
• Non-aggressive
• Human societies extremely diverse
• Monogamy
• Polygamy
– polygyny and polyandry
• For most of human evolution - and for most women in
the world today, menstruation is a rare occurrence
• Repetitive pregnancies and long periods of lactation
Fundamental intersexual reproductive strategies
• Female.
• Maximize resources available to her and her offspring.
• Female primates spend most of their adult lives
pregnant, lactating, and caring for offspring.
• High energy demands.
• Male.
• Produce many offspring and make sure they are yours.
• Non-human primates: androgen levels fluctuate in
response to female receptivity.
Mammalian female reproductive cycle
Female primates
Hormonal suppression of sexual cycles
Nonhuman Cultural Behavior
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Learned behavior shared between generations. t
Chimpanzees: tool use
Spearing of bushbabies
Termite fishing with modified stems and twigs.
Have a preconceived idea of what the finished
tool needs to be in order to be useful.
• May make the tool in advance of the
opportunity for use.
• Preparing for the future. Requires planning and
forethought.
Meat component of chimpanzee diet
Bone review
Genetic similarities and differences
Human and ape chromosomes
A phyletic classification of families
mtDNA
4,700 base sequence
Genes for 11 tRNAs
6 proteins
Human-chimpanzee relationship
1023 more likely than
Chimpanzee-gorilla relationship
Y DNA
Base sequence for
Testis-specific protein Y
Autosomal DNA
Base sequence of
Beta-globin gene cluster
A cladistic classification of families