Animal Biology #13
Simple behaviors include growth movements (tropisms) and locomotor movements (taxes, kineses). Complex innate behaviors are called instincts; they tend to be inflexible, and no time is wasted in learning them. Learned behaviors vary more with circumstance, but a learning period is a necessary prelude.

Tropisms are growth or turning movements in plants or sessile animals. Tropisms and taxes directed toward a stimulus are called positive; those directed away from the stimulus are called negative.
  • Phototropism: growth or turning toward light (positive phototropism) or away from light (negative phototropism).
  • Geotropism (gravitropism): growth toward or away from the earth's center.
  • Chemotropism: growth toward or away from a chemical; special types include halotropism for salt or hydrotropism for water.
  • Anemotropism: growth toward or away from a source of wind.
  • Thigmotropism: growth toward or away from something touched.
Taxes: Oriented locomotor behaviors.
  • Phototaxis: motion toward or away from light.
  • Geotaxis: motion toward or away from the earth's center.
  • Chemotaxis: motion toward or away from a chemical; special types include halotaxis for salt or hydrotaxis for water.
  • Anemotaxis: locomotion upwind (positive) or downwind (negative).
  • Rheotaxis: swimming upstream (positive) or downstream (negative).
Kineses: Non-oriented locomotion, with no particular direction.
  • Photokinesis: locomotion in response to light.
  • Chemokinesis: locomotion in response to chemicals.
  • Thigmokinesis: locomotion in response to touch.
Instincts: Complex, innate behavior patterns.
  • "Complex" means that several acts need to be done in proper succession.
  • "Innate" means inborn or genetically programmed. A standard test is whether animals raised alone from birth can perform the behavior correctly.
  • Usually stereotyped, meaning that the behavior does not vary from one occasion to another or one performer to the next (good for courtship and species-recognition behavior).
  • Advantage: No time or effort is wasted in learning or in making mistakes; behavior is correct the first time.
  • Disadvantages: Cannot be modified to suit circumstances.
  • Examples: Most aggressive or submissive postures and movements; courtship and mate-attracting behaviors (songs, etc.), nest-building behaviors in many species, web-weaving in spiders, territoriality.
Learned behavior: Behavior that improves with practice. Learned behavior is more variable, an advantage in interactions with the local environment, but a disadvantage in mate recognition or courtship.
  • Advantages: Can be varied to suit local circumstance; can become more complex than instincts.
  • Disadvantages: Learning (and mistakes) must take place first; youthful inexperience is a price. The amount of possible learning is limited by neural complexity.
Imprinted behavior: Behavior learned very early in life.

Conditioned learning: Any behavior with a pleasant result will be reinforced and repeated; behavior with an unpleasant result is discouraged. If the outcome depends on pre-existing stimuli, subject will learn to discriminate on the basis of those stimuli.

"Insight" or "rational" learning (mostly in mammals): Solution occurs all at once, in a "flash of insight" (or "aha!"). Much learning occurs in play and exploratory behavior and by imitation.

Symbolism and language: Primates can be taught that a stimulus has an arbitrary meaning (if it stands for something else). The highest form of symbolism is language.

Learning and intelligence: Intelligence is a capacity for learning increasingly complex behaviors. It correlates with brain size only if species of similar size are compared. Mammals are generally the most intelligent animals. Symbolic behavior and language are keys to human intelligence.

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