Knowt 7.2 - Primate Behavior

Part 2 - Reproductive Behaviors and Modeling Evolution

Reproductive Strategies

1. Behaviors that have been naturally selected to increase individual reproductive success.

2. r/K selection Theory (i.e., K-selected vs. r-selected species)

3. Life history traits more important

r-selected species

Minimize parental investment with many offspring

K-selected species

Maximize parental investment with one to two offspring

Parental Care

1. Mother-Infant connection is the basis of all primate social groupings

2. Fathers rarely help rear offspring, b/c uncertainty

3. "Mothering” is a learned behavior (not innate)

Sexual Selection

The competition for mates that leads to evolution of certain traits

Dimorphism

The existence of two distinct forms within a species

Two Types of Sexual Selection

1. Intersexual Selection

2. Intrasexual Selection

Intersexual selection

1. Mate choice, often females

2. exaggerated (ornamental) traits

3. Between different sex

Intrasexual Selection

1. Competition for mates, often between males

2. Males typically much larger than females

3. Between same sex

Infanticide

The killing of young offspring

Infanticide Info

1. Male more common perpetrator

2. Frequently occurs when unfamiliar males enter a new group

3. Other possible explanations:

   • Competition for resources?

   • Accidental killing?

Alloparenting

The practice of caring for other’s offspring

Alloparenting Info

1. Also considered an affiliative behavior

2. Why alloparent?

   • To teach juvenile females

   • direct reciprocity (cohension)

   • Increase indirect fitness

   • Mothering

Model Development

1. Examining behavior

2. Drawing correlations

3. Development hypothesis

1. Examining Behavior

Patterns that have evolved as adaptive responses

2. Drawing Correlations

Between those behaviors and human behavior

3. Developing hypotheses

To test the ecological and genetic factors that produced modern human behaviors

Encephalization

Larger brain weight relative to body mass over time

Index of Encephalization

The predictable relationship between brain and body size

Hominin Brains developed in response to….

1. Diet

   • Provisioning strategies

     • Process, think, engage, create, innovate

2. Social Living

   • Higher fitness, larger brains

Language

A standardized system of arbitrary vocal sounds, written symbols ,and

gestures used in communication.

NHP’s Call Systems

Patterned sounds and utterances that convey meaning

NHP’s Call Systems Info

1. Limited

2. Stimuli-dependent

3. Discrete meanings

4. Nearly-identical species wide

NHP’s Info

1. They cannot speak, but they can learn and use language

2. Examples

   • Washoe and Loulis - ASL

   • Sarah - Arbitrary markers as signs

   • Chantek - used ASL to refer to out-of-view

   • Sherman and Austin - symbolic categories

Broca’s Area

1. Frontal Lobe

2. Speech Production

3. Translates inputs into muscle movements

4. Broca’s Aphasia (“non-fluent aphasia”)

Wernicke’s Area

1. Temporal lobe

2. Language comprehension

3. Wernicke’s aphasia (“fluent aphasia”)

Aphasia

A language disorder that affects a person’s ability to communicate

FOXP2 Gene

1. Regulatory gene

2. Highly conservative

3. Chromosome 7

Human & Primate Comparison Image

Cultural Behaviors

1. Behaviors that are learned and transmitted

   • E.g. Japanese macaques and their taters (you know, '“po-tay-toes”)

2. Variation observed between groups

   • E.g. Orangutans and chimpanzees

3. Tool Use

   • Implies Planning and forethought

   • preconceived ideas

The Evolution of Prosocial behaviors

1. actions that benefit other individuals or the group

2. includes assistance, sharing, caregiving, and compassion

3. Altruism

4. Empathy

Altruism

Helping others at great risk to oneself

Empathy

The ability to identify with the feeling and thoughts of another individual

Why? - The evolution of prosocial behaviors:

1. To ensure offspring or relative lives to reproductive age

2. Reciprocation

3. Kin selection ("for the good of the family!")

4. Group selection ("for the good of the group!")

Main Ideas

• Some behaviors increase an individual's reproductive success – we call these behaviors"strategies"

• reproductive strategies depend largely on life history traits and other ecological factors

• primates are described as K-selected species; females give birth to very few highly dependent offspring over the course of their lives

• sexual selection and dimorphism is the result of different strategies

• infanticide is a strategy often perpetrated by males entering new groups

• alloparenting is another reproductive behavior with positive impacts on an individual's reproductive success

• anthropologists develop models by making observations, comparisons, and hypotheses.

• models to explain the difference between human and nonhuman primate characters that can be tested as hypotheses about human evolution

• examples include encephalization, symbolic thought, language, and culture

• our goal is to apply knowledge gained in the present to our understanding of hominin evolution in the past