Levels of Organization and Causation
1) Levels of Organization
a) Composition
b) Interactions
2) Time Scale
a) Composition
b) Interactions
3) Scientific Perspectives and Organization
4) Causation
a) Aristotle’s Four Causes
i) Material Cause
ii) Efficient Cause
iii) Formal Cause
iv) Final Cause
b) A Reformulation of Aristotle’s Four Causes
i) Material Cause => Composition
ii) Efficient Cause => Proximate Cause
iii) Formal Cause => Organization
iv) Final Cause => Function
(1) System Function
(2) Evolutionary adaptive function
5) Army Ants
page 2
1.A. Levels: Composition
Video: Fall webworms
One meaning of the term Levels is composition: A thing X is at a higher level of
organization than a thing Y if X is composed of Ys (and possibly other things). For
example, cells are at a higher level of organization then DNA molecules, because
among other subcellular structures, cells are composed of DNA.
Galaxies
Planets
Ecosystems
Societies
Groups, Populations
Multicellular Organisms
Cells
Subcellular
Structures
Proteins, DNA
Subatomic
Particles
Notes:
page 3
Compositional Levels do not reveal how the components at one level interact to
produce the behavior and organization of things at a higher level. Thus, for
example, merely knowing that a group is composed of individuals of a particular
species (e.g., army ants, wild dogs, or humans), tells us very little about the social
structure of the group or how the individuals develop in the context of the group.
1.B. Levels: Interactions
Another meaning of Levels is the number, strength, and kinds of interactions
among components at different levels of composition. The interactions of
components at a given level constitute levels of organization. Organization often
emerge from simple interactions of components as we saw with fall webworms
and as we will see with army ants below.
Example: Aggregation Rules
Complex systems, however, are not limited to interactions (i.e., interactional
complexity) with components at one level of compositional. For example,
oxytocin, is a peptide hormones, involved in the process of birth and nursing in
mammals and social behavior, but there are many other physiological processes
and behavioral interactions required for these processes to occur. The particular
function of a hormone such as oxytocin on the state and environment of an
organism, i.e., its context or the situation. Vasopressin, a peptide hormone closely
related to oxytocin is best known for regulating kidney function. If the vasopressin
gene is defective, mammals such as rats will develop diabetes insipidus. But, it
also plays a role in social behavior and anxiety and appears to modulate early
locomotor and social development in rats. It may also modulate early sensorimotor
development, making it a prime candidate for playing a role in autism.
The figure above is a rather rough ordering of different systems in terms of the
levels of complexity of their interactions. Note, for example, that although
galaxies are at a very high level of composition (i.e., they are composed of many
different kinds of things) they are at a low of interactional complexity. That is,
many of the things that a galaxy is composed of do not directly interact other than
overall gravitational forces. For example planets and any living things that may be
Notes:
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on them have negligible influences on the organization of galaxies—of course
galaxies are composed of complex systems, it is just that they are not complex
systems by virtue of being composed of complex systems.
Groups, Populations
Multicellular
Organisms
Societies
Proteins, DNA
Subatomic
Particles
Galaxies
Planets
Cells
Subcellular
Structures
Simple
Ecosystems
Complex
Interactions
A. Composition ! Interactions
If we plot systems in terms of their compositional level versus their interactional
level, we see that there is not a simple relationship between the two.
Confusing these two levels can and has led to oversimplifications of the
relationships between behavior and development, genes and development, and
evolution and development.
Later we will see that these two levels have different meanings of Causation
associated with them.
Notes:
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Composition
Galaxies
Planets
Ecosystems
Societies
Groups, Populations
Multicellular Organisms
Cells
Subcellular
Structures
Proteins, DNA
Subatomic
Particles
Interactions
Notes:
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2.A. Time Scale ! Composition
When we look at the time scale of processes, we see that compositional level and
time scale are closely correlated (the figure below is only an approximate
representation of the relationship).
Composition
Galaxies
Planets
Ecosystems
Societies
Groups, Populations
Multicellular
Organisms
Cells
Subcellular
Structures
Proteins, DNA
Subatomic
Particles
Time Scale
Notes:
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2.B. Time Scale: Interactions
Interactions
As I mentioned last time, a myth of developmental psychobiology is that if systems
(e.g., the development of an organism, ecological systems, species) change on
different time scales, then one can study one type of system relatively
independently of the other. This can lead to error, as we will see in this course.
Notes:
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3. Scientific!! Perspectives and Organization
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Earlier I said that the function of a hormone such oxytocin depended on the state of
an organism (e.g., whether it is pregnant) and its environment (including social
context). From a researcher’s point of view, questions of function and mechanism
Notes:
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lead to different views or perspectives of a system. Depending on how we view a
system can lead to different ways of decomposing a system that is at the same
level of composition.
In the diagram above, I have illustrated different perspectives one may take in
studying a piece of granite and a fruitfully. In the case of the piece of granite,
taking different perspectives leaves us with the same, relatively simple description
of components. However, with the fruitfully, depending on the perspective and
questions asked, we get descriptions of complex systems, which differ according to
perspective.
4. Causation
By our ordinary meaning of causation, we understand the relationship between
cause and effect as one of conditions that bring about certain effects. For
example, throwing a ball and thereby breaking a window. The summation and
integration of excitatory and inhibitory postsynaptic potentials bring about action
potential in a neuron.
Causation in this sense is proximate, which means that the conditions bringing
about an effect are near their effects in space, time, and typically at the same
level of organization.
Aristotle, a famous ancient Greek philosopher, had a more general notion of
causation. He thought of causes as reasons or factors explaining the objects and
processes that exist in the world. For Aristotle there were four basic causes:
1. Material Cause: The material of which a thing is made.
2. Efficient Cause: The conditions that combine to produce an effect from a
cause.
3. Formal Cause: The shape, configuration or type of thing something is.
4. Final Cause: The purpose or end of a thing or process.
Notes:
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Aristotle held that anything could be explained in terms of these four causes. For
example, the material cause of a statue is the stone it is made of. Its efficient
cause is all the chiseling required to transform the stone into a shape or
configuration, its formal cause, which was the purpose or aim of the sculptor who
produced it, its final cause.
There is a ring of truth to Aristotle’s four causes as explanations for why a thing is
the way it is, but Aristotles four causes require a modern reinterpretation in light
of modern science.
Indeed, there are modern ideas that correspond neatly to Aristotle’s four causes.
They are:
1. Composition: Composition corresponds very closely to Aristotle’s notion of
material cause. It is the components, entities and processes that compose a
system at some level of organization. For example, DNA, RNA, and Proteins
are among the components making up cells.
2. Proximate Cause: Proximate cause also corresponds very closely to
Aristotle’s notion of efficient cause. These are the causal conditions specified
in mechanisms for how things work, such as the firing of a neuron, or hormonal
factors that modulate reproduction and maternal care of young.
3. Organization: Is one aspect of Aristotle’s notion of formal cause, namely the
idea of configuration. But, specifically we are primarily concerned with the
configuration of interactions. Interactions connect organization to composition
and proximate cause.
A. Interactions are among components of a systems, and
B. Interactions are proximate causal relationships among components.
4. Function: The notion of function is the biggest departure from Aristotle’s
system. Final causes assume a purpose for a component or system. This is fine
for ordinary human artifacts. A purpose of a table is to set things on, and this is
a reason for it existence, but final causes are neither testable nor explanations of
natural systems. Thus, in biology and psychology we replace Aristotle’s notion
Notes:
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of final cause with two related concepts of function. Functions in either sense
are understood in terms of their consequences.
A. System function: This is the role of a component in a system. For
example, a function of a neuron is to modulate action potentials. A
function the heart is to circulate blood. System functions depend on the
composition of components, their proximate causal interactions, and
how these interactions are organized (e.g., the configuration of
excitatory and inhibitory inputs into a neuron, branching nature of the
circulatory system).
B. Evolutionary adaptive function: This is the role of a component in the
survival and reproduction of a system in a larger ecosystem or
environment. Typically, adaptive functions are ascribed to components
and characteristic of individuals, but they may apply to entities at other
levels of organization such as groups, ecosystems, and species.
Army Ants
Army ants are an interesting example of the complexities of organization and the
different kinds of causes operating during development.
What makes this example especially interesting is that individual insects such as
ants are in many respects much “simpler” (this is a relative term, ants are
nevertheless quite complex systems) than birds or mammals in the complexity of
their nervous systems, their behavioral repertoires, and in their capacity to learn.
T. C. Schneirla studied army ants (Eciton hamatum and E. burchelli; other
websites 1, 2, 3) throughout the 1940s. Army ants are nomadic foraging social
insects. Unlike many other social ants, wasps and bees they do not build
permanent nests. [Videos: 1 2 3 4]
One of the more remarkable aspects of army ant social behavior is that individual
development is highly coupled with social behavior and individual development
drives social behavior.
Notes:
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Cycles of Behavior
Army ants (50,000-120,000 in a colony) exhibit daily or diurnal cycles of
functional activity. Functional activity includes daytime foraging (when light,
temperature and humidity are best), thermoregulation and climate control in the
bivouac. These functional cycles are largely under external control of the daily
light cycle, temperature and humidity conditions. These are external Zeitgebers.
They go through Nomadic and Statary phases of colony behavior that are tightly
coupled with development of offspring. Interestingly, these cycles are not driven
by external Zeitgebers but emerge from the individual interactions of workers,
new workers and pupae.
Notice that all four types of causes are present Schneirla’s representation.
! The Colony Functional Cycle refers to the functions performed by the colony
such as foraging and incubation, care and feeding of the next generation.
! The Brood Cycle corresponds approximately to the notion of proximate
causation, though later we will distinguish types of proximate causal relations
that occur at different time scales such as ontogenetic causation.
The Typical Raiding Pattern illustrates one aspect of the organization in army
ants, particularly, foraging search patterns, which are the result of simple
individual rules of behavior.
Notes:
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Notes:
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How are these functional cycles, and synchronous reproduction and development
generated? According to Schneirla they are due to local interactions between
newly emerged workers and the current work force and subsequently reciprocal
interactions between workers and the developing brood.
1. Newly eclosed brood (first spike above threshold): Newly emerged works
increase the activity levels of old workers in the workers lick and groom the
newly emerged workers due to chemical signals.
Notes:
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2. Developing larvae (the second more gradual rise): Workers are attracted in
the presence of larva pheromones and nutritive secretions that the workers
ingest. Larva also become more active in the presence of workers, who feed
them. Activation of workers spreads throughout the colony.
This process of behavioral excitation and activation of workers is not merely timed
by the length of time it takes the larva to develop. Increase activation stimulates
the nomadic phase, foraging activity is increased, increasing the food supply
needed for growth and maturation of larvae.
Notes:
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The contents of Psychology 113, Developmental Psychobiology, as taught by Dr. Jeffrey C. Schank during the winter
2012 academic quarter at the University of California, Davis, are COPYRIGHT Jeffrey C. Schank (c) 2000-2012.
All federal and state copyrights are reserved for all original material presented in this course through any medium,
including lecture or print.
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