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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.
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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-and-error learning. • 2. Possibile genetic resistance to disease and parasites. • 3. Efficient location of food resources • 4. Increases the reproductive fitness of group members.
Polygyny: one reproductively mature (RM) male, several RM females Gelada baboon
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 • 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.
Genetic similarities and differences Human and ape chromosomes
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