Unit 5 Flashcards
dependent variable
the variable predicted to change in response to changes in the independent variable
independent variable
variable that is altered to measure the changes in the dependent variable
allometric relationships
Undrestanfing growth patterns explain how biological traits scale with size across individuals and species for understanding growth patterns, metabolic rates, and structural adaptations in different organisms.
alloparental care
care of offspring by individuals other than the biological parents
infantacide
the deliberate killing of an infant by a parent, caregiver, or other individuals. It occurs in both human societies and the animal kingdom for various social, economic, or evolutionary reasons.
provisioning
supplying and providing resources or protection
2 pair bond hypothesis
1) bonds evolved to become more stable in response to increased need for male provisioning
2) pair bond stability has varied/evolved in response to differing degrees of male competition resulting from variation of female availability
Trivers Parental Investment theory
– Humans evolved to form stable bonds to increase offspring survival by ensuring bi-parental care.
- predicts the amount of paternal care a male contributes depends on a # of factors
- time is determined by success or survival of offspring
- offspring survival highly dependent on external care= selection pressure for best female
- if not externally dependent there is a decrease in parental care and post conception pair bond.
who is expected to invest more in parental care of off spring
females allocate more time and energy, with gestation and lactation taking up a lot of energy, with less reproduction opportunity each off spring is more valuable.
what factors effect the amount of paternal investment of a male
- personal fitness benefit
- paternal confidence
- male/female ratio other mating chances
- the measured increase in survival rate of infant (if more will help)
- social structure/mating system
- availability of resources
MALES INVEST WHERE THERE IS THE BIGGEST PERSONAL PAY OUT
Polygyny
mating system where one male has multiple female partners and females typically just have one male.
when does Polygyny result in stronger bonds
- females having strong support systems decreasing conflict and allowing males to provision
- reduced male competition w/in the group
- defined social roles
- shared parenting
mens show off work
engagement in high risk behavior in highly visible fashion to show off their mating qualities. typically in early mating stage.
why do males need to provision through breast feeding
- lactating females use a lot of energy
- females carry the baby and have reduced capacity to provision
- single mothers would see a reduction in fitness and risk survival without male
- female is less able and then there is also shared energy consumption
factors that strengthen pair bonding
- form stable bonds to increase offspring survival by ensuring bi-parental care.
Sexual Dimorphism & Mate Guarding
Cooperative Breeding – Humans evolved with alloparental care
Extended Juvenile Dependency
Resource Sharing & Division of Labor –
factors that weaken pair bonding
Reproductive Strategies – Males evolved to maximize reproduction through multiple partners, while females prioritized selective mate choice for resources.
Paternity Uncertainty – Males may abandon partners
Resource Scarcity & Stress break to seek better survival strategies.
Age & Fertility Differences
Social & Cultural Evolutionary Shifts – marriage norms changed,
Polygyny & Status Competition – high-status males monopolized multiple mates, reducing long-term bonding incentives.
Opportunity for Better Mates (Mate Value Shifts)
Increase in female provisioning male not needed
predictability of resources leads to:
stable/reliable leads to increased family structure and bonding
unpredictable leads to decreased family structure increasing male abandonment and short term strategies for mating
traits females are attracted to
resource gathering
strength
deep voice
traits males are attracted to
cues related to fertility eg. age, hips, health
The Handicap Principle
- suggest that male traits such as muscles are costly to produce and to maintain and only the fittest males are able to produce and maintain them
- testosterone is a key factor but costs energy and surpresses immune function= vulnerability
- flashy traits like muscles or a peacocks tail advertise male fitness and probability of survival
why are human voices and faces signs of underlying mate value
voices and faces are a result of hormones = genetic quality and overall heath
testosterone
estrogen
factors that contribute to cross cultural variation in mate perference
- resource predictability
- socioeconomic factors
- norms and socialization
- parental investment
- reproductive strategies
