Evolutionary Adaptiveness and Human Psychology

Environment of Evolutionary Adaptiveness (EEA)

• EEA refers to the specific environmental conditions that shaped a species' adaptations
• It explains why certain traits evolved in response to environmental challenges and needs
• Factors in the EEA include food availability, climate, social structures and predators

Examples of Adaptations

• Fins in Whales: Whales evolved fins due to the need to navigate water efficiently
• Eyes in Animals: Eyes evolved independently in multiple species due to the presence of light

EEA of Human Psychology

• The EEA refers to the conditions in which human psychological traits evolved
• Identifying when traits emerged can reveal the environmental pressures that shaped them
• Human brains' massive changes over evolutionary time are contextually explained by the EEA

Biological Changes in Humans: Brain Expansion

• Human brains expanded dramatically in evolutionary terms.
• Our closest relative, chimpanzees, have brains around 350 cubic centimeters
• Modern humans have brains averaging 1,450 cubic centimeters
• Most significant brain growth occurred between 2 and 6 million years ago, with the steepest rise in the last 2 million years

Changes in Brain Shape

• Human skulls evolved with a higher forehead and a more rounded shape, contrasting with flatter skulls of early ancestors.
• This change reflects an expansion of specific brain regions like frontal lobes

Frontal Lobe Development

• Frontal lobes are responsible for planning, high-level thinking, executive function and social intelligence
• The other brain areas, like the occipital lobe, responsible for sensory input did not grow as significantly during human evolution.

Role of EEA in Brain Expansion

• The environmental and social pressures that early humans faced, such as hunting and gathering, cooperation, and survival in small groups, likely drove the expansion of their brains and associated cognitive abilities

Neanderthals and Human Brain Comparisons

• Neanderthals had even larger brains (1,550-1,600 cubic centimeters) than early humans, but their brain anatomy varied.
• Despite the larger brain size, anatomical differences, social intelligence and adaptability contributed to the eventual outcompeting of Neanderthals by humans

Mismatch Theory

• Explains the disconnect between human adaptations of the past and rapid changes in modern environments
• Evolution is too slow to keep up with changing conditions
• This creates "mismatches" between evolved traits and lifestyles

Evolutionary Time Lag

• Evolution takes several generations to produce significant genetic changes

Evolutionary Background

• Humans evolved in small, close-knit groups (50-200 individuals)
• Nomadic lifestyle, relying on food sources in frequently changing environments
• Faced scarcity, necessitating resourceful and efficient energy storage, and close-knit social interactions.

Modern Environment

• Development of agriculture and technology accelerated changes in the human environment.
• This rapid change creates environmental mismatches
• Modern lifestyles and urbanization differ significantly from the environment in which humans evolved.

Examples of Mismatch

• Diet and Cravings: Evolution favored cravings for calorie-rich foods when they were scarce, but modern environments make these foods readily available, leading to health problems.
• Social Interaction: Modern, intricate social networks—online and in person—can stress our brains, which are not adapted to this kind of magnitude of interaction and comparisons.
• Stress Responses: Modern stressors, like work or societal pressures, trigger the same fight-or-flight responses as the immediate threats our ancestors faced but often without resolution.
• Cognitive Challenges: Humans struggle with processing complex societal challenges since these tasks are very different from the kind of survival problems humans evolved to solve.

Small Changes Over Time

• Lactose tolerance: Populations that domesticated milk-producing animals developed lactose tolerance.
• Spleen Adaptations: Some human populations have developed spleen adaptations for increased diving ability.
• Vision Correction: Glasses and contact lenses mitigate the disadvantage of poor eyesight.

Addiction and Behavioral Traits

• Exposure to addictive substances for many generations may lead to increased tolerance.

Art and Creativity

• Artistic expression may be a by-product of other complex traits, like pattern recognition

Evolutionary Timeframes

• Major physical changes require thousands of generations under persistent selective pressure

Sex and Sex Differences

• Evolutionary success hinges on survival and reproduction
• Reproduction is complex; involving selection of mates who will increase survival chances for offspring

Sexual Motivation and Behavior

• Males are often more driven to compete for mates
• Females are typically more selective

Parental Investment

• Parental investment refers to resources a parent allocates to raise offspring
• Females typically invest more in offspring, leading to greater mate selectivity
• Males often have lower parental investment, leading to more competition

Sexual Selection and Mating Strategies

• Differences in parental investment lead to differences in mate selection strategies
• Males often exhibit more elaborate traits to attract females
• Females tend to be more selective and prioritize traits signaling good genes and resources

The Sexual Division of Labor in Reproductive Costs

• Parenting costs: Energy, resources, and effort put into raising offspring; primarily borne by females.
• Mating costs: Effort put into finding and securing a mate; primarily borne by males.

Biological Continuity

• Aggression and dominance behaviors likely derive from a common evolutionary ancestor

Cultural Reinvention Hypothesis

• Humans are culturally shaped blank slates
• The substantial consistency of gender differences across multiple species would appear to contradict or weaken this account.

Interaction of Biology and Culture

• Human aggression—both patterns and cultural expressions—are shaped by a complex interplay between biological predispositions and cultural influences.

Sex Differences in Earning Potential

• Women prioritize earning potential in partners
• This preference is consistent across cultures and levels of gender equality
• Underlying reasons may include historical economic disparities, evolutionary factors and a potential offset for gender disadvantages.

Sex Differences in Age Preferences

• Men generally prefer younger women
• Women generally prefer slightly older men or men near their own age

Why Do Men Like Younger Women?

• Evolutionary explanation points to links between women's facial symmetry and perceived youthfulness and fertility, which are attractive to men.

Sources of Sexual Conflict in Relationships

• Sex differences in desires related to short-term versus long-term relationships and sexual novelty

The Eerie Fact About Affairs

• Men and women's levels of happiness are not noticeably different whether or not they had experienced an extramarital affair.

This quiz explores the concept of the Environment of Evolutionary Adaptiveness (EEA) and its influence on species adaptations, particularly in humans. It delves into examples of adaptations and discusses the evolutionary pressures that shaped human psychological traits and brain expansion. Test your understanding of these crucial evolutionary concepts.