13: Adaptation

Frugivory

• Exploiting short-lived, patchy resources

• Fruit properties

• Complex spatial representations

• Good memory

Extractive foraging

• Exploiting foods that are difficult to process may have favored special cognitive skills

• Consumption of difficult to process foods (need to use tools)

• Complex, multi-step activities

• Fine motor skills

Social intelligence

• Many small-brained animals are extractive foragers and frugivores, so the ecological hypotheses don’t necessarily explain intelligence

• Triadic awareness of rank and friendship

  • Is A better friends with B than A is with me?

  • This matters if I have a fight with B and ask A for help!

Episodic intelligence - monkeys

• Good observational skills, situational awareness, and recall, but no evidence that they can reflect on their knowledge or make predictions

Self-awareness – apes, Australopithecines

• Problem-solving, tool use, cultural behaviors, political and moral behaviors

• Humans the only ones with foresight (ability to plan and predict)?

• Theory of mind? – perhaps chimps and Australopithecines have this on a limited scale

Mimetic intelligence – H. erectus

• At time of H. erectus (~2 mya), major changes – more complex emotional expressions and communication, more varied sounds, more elaborate culture

• Type of cognition needed to learn music, crafts, and sports (imitation, without language)

• Takes episodic fragments and connects them into linear sequences

• Underlies body language, gestures – group and mood synchronization, emotional expression, laughing, crying, shouting, etc.

Mythic intelligence – Neanderthals, Cro-Magnon

• Language possibly developed to support distinctions that need to be made in increasingly complex social organizations

• Motor cortex controlling movements in face, mouth, tongue, and larynx becomes Broca’s area

• Wernicke’s area – sound sequences and vocal calls

• New kind of culture – mimetic culture becomes governed under integrative myths (stories of how things are)

Theoretic intelligence – modern H. sapiens

• External information storage tools (writing, computers)

Reflexivity – we can use language to talk about language itself

Displacement – ability to discuss past and future

Arbitrariness – relationship between object and word is arbitrary

Productivity – ability to create new words and use existing resources to describe new objects/concepts (ex: google)

Cultural transmission – passed from one generation to the next, including accents and expressions

Duality – distinct sounds and distinct meanings (sounds do not have meaning when isolated…combination of sounds produces a distinct meaning)

Multiregional hypothesis

• Homo sapiens evolved multiple times, separately on different continents (convergent evolution)

Out of Africa hypothesis

• Homo sapiens originated in Africa and migrated to Eurasia

• More support and DNA evidence for this hypothesis

In North America, human hunters played a part in the extinction of 135 species of mammals

• Mammoths, mastodons, giant sloths, etc.

• Rapidly changing climate at end of ice age?

Disrupted relationship between top predators and prey species (saber-toothed cats, dire wolves)

Similar extinction of marsupials in Australia, New Zealand

• Up to 90%

After Pleistocene: Holocene

• 11,700 years ago

• Warmer climates, but uniform across globe

• Population explosion

Bergmann’s Rule

• If two mammals have similar shapes but different sizes, smaller animal will lose heat more rapidly

• Larger mammals – adapted to cold climates

Allen’s Rule

• Mammals in cold climates have shorter, bulkier limbs

• Mammals in hot climates have longer, narrower limbs

Adapted to hot, open environments

Adaptations

• Increase in sweat glands

• Loss of hair

• Loss of hair meant that more of the body was exposed to the sun

• Skin color adaptations

Cline

• Measurable gradient in the frequency of a gene

Darker skin pigmentation in tropical latitudes and non-forested regions

• Ultraviolet radiation more intense, protects skin

Lighter skin pigmentation in northern latitudes

• Solar radiation is weak, increases vitamin D absorption

Lactose tolerance is rare, worldwide

• Lactase genes allow for digestion of dairy products

• Most mammals stop producing lactase after weaning infants

Humans created selection pressures for lactose tolerance

• Cultures that relied on milk experienced selection for lactose tolerance

Acclimation

• Short-term changes that occur quickly after exposure to stress

• Reversible

• General term describing any change to reduce negative effects of environment

• Ex: Sweating in hot temperatures

Acclimatization

• Physiologic changes that take longer (days to months)

• Reversible

• Artificially induced and short-term

• Ex: Visiting a location with a high elevation for an extended period of time will lead to changes in red blood cell production, lung volume.  If you then return to your home environment, your body will adjust back to a lower elevation.

Adaptation

• Changes to reduce negative effects of environment

• Occur over multiple generations

• Not reversible

• Adaptive physiologic or behavioral changes

• Ex: Being born with genes that affect red blood cell production