“In the future I see open fields for far more important researches. Psychology will be based on a new foundation, that of the necessary acquirement of each mental power and capacity by gradation.”  (Charles Darwin. The Origin of Species, 1859, p. 449.)

BEHAVIOR was neglected for many years because it was ephemeral, not fixed like bones or beaks, feathers or fossils and museum specimens, in ways that allowed systematic study by many observers.   It was the great insight of ETHOLOGY that observations of behavior have great power to inform ideas about how organisms change.  Ethologists (looking for diversity and adaptive change) and comparative psychologists (looking for fixed rules of behavior independent of environments) appeared to compete.

The INTEGRATIVE BIOLOGY of BEHAVIOR involves the coordinated activities of four broad areas (as biologists study them): DEVELOPMENT, ECOLOGY, EVOLUTION, and PHYSIOLOGY and how they are brought to bear on BEHAVIOR (“DEEP ETHOLOGY”

  • EVOLUTIONARY BIOLOGY is concerned with …  study of change across generations — In Art & Organism, evolution emphasizes the “ultimate” causes and consequences of behavior — it looks to ancestors and ancestry of traits and forward to descendants.  The confidence in our beliefs about the (hard to know) past and (ultimately unknowable) future diminishes with time.  Most simply put, evolution studies “descent with modification” that involves “small-scale evolution (changes in gene frequency in a population from one generation to the next) and large-scale evolution (the descent of different species from a common ancestor over many generations).” (Basic evolutionary theory is surveyed nicely in Evolution 101, Berkeley University)
  • A Key concept in evolutionary theory is that of ADAPTATION –a fundamentally simple concept that can quickly become complex as its thread of meaning is followed through the levels of biological organization and their hypothetical scenarios and complexities.  A critical concept: read more
  • Among the most powerful demonstrations of the workings of evolution is Ritualization: the “improvement” of a behavioral pattern that evolved to meet a specific biological need coming to be relevant to meeting another, often very different need.  For example, the selection pressure of sexual selection (natural selection serving traits important in courtship and reproduction) may select for a trait may is an effective or efficient means of communicating–especially the sexual development or motivational state of the actor.
    • A common example is the change in a motor pattern reflecting a homeostatic adjustment to ambient temperature (e.g. feather fluffing to retain heat in a cold atmosphere).  Such behavior is generally the function of the autonomic nervous system.  Such a signal may also function to communicate that the actor is under mild stress.   If it is adaptive to communicate the underlying stress response, exaggeration of some specific aspect (size or shape of feathers) would improve that function. (read more)  When a behavioral pattern is no longer under the control of stimuli which originally evoked it, it is said to be “emancipated.” Amongst the most fascinating examples are signals that began as reflexes of the autonomic nervous system that eventually come under the control of a social stimulus.  That is, a shared causation for adapting to challenges to meeting physiological needs and those to meet social needs (aggression, courtship, reproduction) is often the autonomic nervous system.  (read on). 
  • Exaptation:  “Stephen Jay Gould‘s proposed replacement for what he considered the teleologically-loaded term “pre-adaptation” and the related term co-option describe a shift in the function of a trait during evolution. For example, a trait can evolve because it served one function, but subsequently it may come to serve another.
    • Exaptations are common in both anatomy and behaviour. Bird feathers are a classic example: initially they may have evolved for temperature regulation, but later were adapted for flight. Interest in exaptation relates to both the process and products of evolution: the process that creates complex traits and the products (functions, anatomical structures, biochemicals, etc.) that may be imperfectly developed.” (Wikipedia)


“We are all tattooed in our cradles with the beliefs of our tribe; the record may seem superficial, but it is indelible.”

Oliver Wendell Holmes Sr.  The Poet at the Breakfast Table (1872).


why should an individual relinquish resources (including time and energy) that might contribute to its fitness —

why should it endanger meeting its own needs or promotion of its own offspring? go to  ALTRUISM  (link needs repair)


COMPETITION and COOPERATION. “Evolution is based on a fierce competition between individuals and should therefore reward only selfish behavior. Every gene, every cell, and every organism should be designed to promote its own evolutionary success at the expense of its competitors. Yet we observe cooperation on many levels of biological organization. Genes cooperate in genomes. Chromosomes cooperate in eukaryotic cells. Cells cooperate in multicellular organisms. There are many examples of cooperation among animals. Humans are the champions of cooperation: From hunter-gatherer societies to nation-states, cooperation is the decisive organizing principle of human society. No other life form on Earth is engaged in the same complex games of cooperation and defection. The question of how natural selection can lead to cooperative behavior has fascinated evolutionary biologists for several decades.

A cooperator is someone who pays a cost, c, for another individual to receive a benefit, b. A defector has no cost and does not deal out benefits. Cost and benefit are measured in terms of fitness. Reproduction can be genetic or cultural. In any mixed population, defectors have a higher average fitness than cooperators. Therefore, selection acts to increase the relative abundance of defectors. After some time, cooperators vanish from the population. Remarkably, however, a population of only cooperators has the highest average fitness, whereas a population of only defectors has the lowest. Thus, natural selection constantly reduces the average fitness of the population. Fisher’s fundamental theorem, which states that average fitness increases under constant selection, does not apply here because selection is frequency-dependent: The fitness of individuals depends on the frequency (= relative abundance) of cooperators in the population. We see that natural selection in well-mixed populations needs help for establishing cooperation.” 

 fromFive Rules for the Evolution of Cooperation” Martin A. Nowak 2006:


Here Nowak discussed five possible mechanisms for the evolution of cooperation:

  • kin selection (relinquish personal fitness for others with whom you share more-or-less genes)
  • direct reciprocity (exchange of favors with another individual, probably frequently encountered)
  • indirect reciprocity (offering favors with expectation of reciprocity as a cultural norm; enhances reputation)


LOOKING more DEEPLY: Like humans, mice can feel each other’s pain … and comparable brain areas are involved (see Smith et al. 2021)


“For the first time in 4 billion years a living creature had contemplated himself and heard with a sudden, unaccountable loneliness, the whisper of the wind in the night reeds.”

Loren Eiseley