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including Ross McIntyre, Kendall Smith, Steven Gillis,
Paul Baker, Richard Robb, and Margaret Favata, all
played instrumental roles in the identification, isolation,
purification, and characterization of the IL-2 molecule.
In 1960, Nowell made the serendipitous discovery
that kidney bean extract containing a compound called
phytohemagglutinin (PHA) induced the division of
lymphocytes, which were previously thought to be endstage cells that lacked the ability to proliferate. Soon
thereafter in 1965, two seminal papers appeared in the
journal Nature describing the discovery of a blastogenic
activity found in the culture media of stimulated
lymphocytes that promoted their proliferation. However,
the responsible agent in the lymphocyte “conditioned
media” was yet to be characterized as a single molecule.
In 1972, Smith, who had previously been at the
National Cancer Institute (NCI), joined McIntyre’s
hematology research laboratory at Dartmouth as a
postdoctoral fellow. The primary research interest of
the laboratory at that time had been antiviral factors
called interferons. Following a loss of funding in 1973,
Smith traveled to France where he continued his
immunological training with Georges Mathe, who was
using immunotherapy to treat leukemia. By 1974, Smith
had returned to Dartmouth as an Assistant Professor of
Medicine in the Division of Hematology and Oncology.
As head of his own laboratory, Smith recruited Gillis to
join his lab as a predoctoral fellow, and Paul Baker joined
the lab in his own postdoctoral fellowship. In 1976,
a report from the NCI showed that the “lymphocyte
conditioned media” could support the long-term growth
of T lymphocytes in culture. This activity was most likely
caused by the same ingredient that had already been
identified as the blastogenic factor a decade earlier in the
Nature papers.
With his small team at Dartmouth, Smith set out to
find the active ingredient in the lymphocyte conditioned
medium that was responsible for the long-term T cell
growth. Several critical discoveries by Smith’s team
over the next decade eventually led to the isolation and
characterization of the molecule now known as IL-2.
First, Steven Gillis successfully derived long-term T cell
lines using mouse T cells, thereby confirming the earlier
report from the NCI. Next, Paul Baker derived the first
T cell clones (progeny of a single cell). These unique
cellular reagents were instrumental in the construction of
a new bioassay for the T cell Growth Factor (TCGF), as
Smith’s team named it. By 1979, Gillis and Baker had left
the Dartmouth lab, and two new people were continuing
the research. Richard Robb, a postdoctoral fellow,
painstakingly purified the TCGF activity from liters of
lymphocyte-conditioned media, while Smith used the
bioassay to quantify the purified fractions. By 1982,
the recently arrived Margaret Favata had successfully
22
generated monoclonal antibodies reactive with the IL-2
molecule, enabling the purification of milligram quantities
of IL-2 to be purified through a one-step affinity process.
Through these steps and years, Smith and his laboratory
isolated and characterized the IL-2 molecule in addition
to identifying the IL-2 receptor. By 1983, they were able to
publish in The Journal of Immunology on the development
of monoclonal antibodies and their discovery of the IL-2
molecule.
The IL-2 molecule is now known to be a 15.5 kDa
globular glycoprotein of 133 amino acids. Its discovery
and the characterization of its structure and function
have been instrumental in the development of an
entirely new class of “immunological molecules.” IL-2
serves as a prototype for the group, which currently
includes 29 members. These are considered to be the
“hormones of the immune system,” the immunological
equivalent to those in the endocrine system. They serve to
‘communicate’ between the varying cells of the immune
system and lead to their development, reproduction, and
responses to invading, foreign microbes.
The influential discovery of IL-2 brought research
within the medical community to a new level, furthering
the understanding of the complicated human immune
system. The understanding of IL-2 and its functions has
already aided researchers in developing new treatments
for immunological diseases. Most immunosuppressive
therapies used today, such as glucocorticoids and
cyclosporin-A, are now known to act by blocking the
production and activities of IL-2. In addition, applications
of interleukins include new experimental immune-based
therapies, now being pioneered by Smith and others, for
the treatment of cancer and chronic viral infections, such
as those due to HIV and hepatitis C virus. Researchers
have also developed monoclonal antibodies reactive
with interleukins and cytokines as new treatments for
rheumatoid arthritis and inflammatory bowel disease.
These applications provide hope for future treatments of
immunological diseases, as well as for both cancer and
HIV, through continuing research in the rapidly evolving
field of molecular immunology.
The authors would like to sincerely thank both Dr.
McIntyre and Dr. Smith for their illuminating interviews
as well as Dr. Smith for his kind help with editing.
DARTMOUTH UNDERGRADUATE JOURNAL OF SCIENCE
Invasion of the Red Fire Ant:
A Multi-layered Metaphor for Managing Invasion through
the Study of Behavior
TUCKER MURPHY ʻ04
Unlimited pain. Hormiga brava (fierce ant). Formiga
de fogo (fire ant). Formiga lava-pé (wash-foot ant).
Solinopsis Invictus (invincible ant). These are but a few
of the titles garnered by the infamous red fire ant as
it cuts a swathe of invasion and decimation across the
North American countryside. Beyond a show of human
fear and loathing for these tiny ants (and perhaps, a fair
amount of imagination), these names exhibit a true
desire and passion to describe the behavior related to ant
and human encounters. Admittedly, most fire ant aliases
focus only on their ferocious stings and were probably
coined by those who had the misfortune of coming into
contact with it. But it is likely that the scientific name, at
least, takes into account the “Fiery aggression, voracious
feeding, and prolific nest building” characteristic of this
species of ant (Taber 2000). The anthropomorphic nature
of many of these names suggests that humans also tend
to identify with its social ways. Because of the extreme
and social character of this invasive species one cannot
help but find interest in their behavior. It is no surprise,
then, that fire ants have become a classic case study for
behavioral ecologists as well as those biologists out to
prove the severely damaging nature of invasions.
The destruction and the overwhelming ecological
changes wrought by red invasive fire ants and other
exotic invasives with similar behavioral characteristics
demonstrates to even the most skeptical of critics why a
war needs to be waged against invasive species. Ironically,
because they are such successful invaders and because
they are so late in their stages of invasion in North
America, fire ants also illustrate the near futility that is
often involved in the war against invasive species. The
only real weapon humans have on their side in this war
lies within a thorough understanding of themselves and
the enemy, which, in the case of the fire ants, includes their
behavioral flexibility, their eusociality, and their human
commensalism. The invasion of the red fire ant illustrates
the almost inevitable consequences of global change; it
is also a prime example of how human understanding of
behavior can provide, at the very least, a window into the
future and, possibly, a way of altering this future through
changes in the behavior of both ourselves and other
invasives.
SPRING 2003
E.O. Wilsonʼs War Strategy: A Behavioral
Approach
One cannot speak of invasive red fire ants without
also mentioning E.O. Wilson in the same breath. The
path of the fire ant as it sweeps across Southern United
States is inextricably linked with the career of this
famous behavioral ecologist, evolutionary biologist and
world authority on ants. A very young E.O. Wilson first
discovered this invasive species--accidentally introduced
in shipping from South America--in Mobile, Alabama
in 1942 and was the first to publish on them in a study
undertaken for the Alabama Department of Conservation.
From the very beginning, Wilson placed great emphasis
on examining behavior of this invasive species and noted
key characteristics, such as the tendency of colonies to
sometimes adopt queens from outside their own nests
(Taber 2000). His original research led him to a life long
passion in myrmecology and the conclusion that “Ants
are premier organisms for research in behavioral ecology
and sociobiology” (Holldobler and Wilson 1990). The fire
ants, in the midst of a rapid spread in all directions out of
Mobile at the time Wilson first encountered them, have
now expanded their range to all over the southern United
States and are serious pests (Taber 2000). However,
Wilson’s behavioral approach has remained unchanged
in its utility.
The value of his original line of attack has become
apparent over time, as many of his predictions regarding
the invasion have come true (Taber 2000). He understood
the flexible and almost invincible nature of the fire
ant that would allow it to expand into many varied
habitats in the western United States and Mexico despite
humankind’s best efforts at control. In fact, forty years
before Californians discovered a series of infestations in
their own backyards Wilson had predicted their arrival
(Taber 2000). Recently, weight has been added to the
approach Wilson used so well; Holway and Suarez write,
“This information will not only aid control efforts for
particular species, but the identification of behavioral
attributes common to different invasive taxa could
also provide a basis for predicting which species have
the potential to become problematic invaders” (1999).
Essentially, through behavioral studies it is possible to
gauge whether an invading species is like a live warhead
23
ready to explode upon reaching a new ecosystem or
simply a blank.
Perhaps E.O. Wilson’s most prophetic and telling
statement was his labeling of the war against fire ants
as “the Vietnam of entomology” (Taber 2000). Though
those who have mistakenly found themselves in the
midst of a fire ant colony and felt the full fury of their
attacks might see war as an obvious analogy, Wilson’s
comparison operates on a deeper level. The war of which
he speaks is one being fought on a much broader scale
across oceans and continents. It is an effort to prevent
the complete deterioration of the great faunal realms
(Wallace’s realms, corresponding to the main continents)
and subsequent loss of biodiversity throughout the world
due to introduced exotics (Elton 1958). Currently, such
invaders are the second leading cause of extinction in
the world. Though in the case of the red invasive fire ant
most casualties are non-human native species, it is “the
most comprehensive aggressive and costly conflict ever
between man and bug” (Brouwer 2000). Protesters may
not march in the streets over wars with insects, but there
are many a doubter or critic who question whether such
wars are worth the expense. There are still others who
see only inevitability, since humans themselves and their
disturbance and transport have facilitated the invasion.
In the face of such odds, one cannot help but wonder
whether this campaign will end in an outcome similar to
its ill-fated namesake.
Phenotypic Plasticity, High-tech Armaments,
and the Super-Individual
The trouble with the fire ants is that they embody
almost all of the behavioral characteristics of classically
good invaders with the many added benefits derived
from their eusocial behavior. Ignoring for a moment the
social traits particular to the fire ants, there are certain
generalizations that can be made about behaviors that
predispose any exotic to invasion. As outlined by Porter
and Savignano S. invicta posses seven such behaviors:
“(1) It prefers heavily disturbed habitats
associated with human activity. (2) It tolerates a
wide range of climatic conditions and (3) utilizes
a wide variety of food resources. (4) It is relatively
abundant in its homeland. (5) Workers are highly
variable in size, a characteristic that may allow
them to utilize a broader feeding niche. (6) Mated
queens are capable of establishing new colonies
after transport [i.e. effective dispersal]. (7) Finally,
colonies of this species have a high reproductive
capacity; they grow rapidly and can produce
thousands of reproductives per year.” (1990)
100
90
S. invicta discovered in Puerto Rico
80
Mirex registrations withdrawn
70
HECTARES INFESTED x 10
6
EPA started public hearing
on use of Mirex
60
50
Buren's Taxonomic revision
Large-scale program started
to control IFA with Mirex bait
40
30
20
10
Mirex belt developed
IFA control with organochlorine
insectcides discontinued
Federal-state control
program started
0
First survey of IFA distribution
1930
1940
1950
1960
YEARS
1970
1980
1990
Fig. 1. The S-shaped growth curve showing IFA infestation over time as well as some important historical events (Taber 2000).
24
DARTMOUTH UNDERGRADUATE JOURNAL OF SCIENCE
Essentially, these characteristics allow the red fire ant
to adapt a wide variety of habitats, making it a generalist.
Of particular interest is the fourth observation: if a
species is abundant in its homeland (where natural
predators and competitors are present and the species is
confined to a more constricted niche), then there is good
indication that it would be successful if released from its
native restraints.
Of course, it is red fire ants’ social nature that defines
their great capacity for invasion. The success of social
insects across a wide variety of habitats is largely derived
from the added flexibility their sociality allows them.
Such flexibility is extremely beneficial to new invaders
“that must quickly learn about, exploit and respond to
new resources and challenges in receiving communities”
(Moller 1996). Individual ant workers can survive on
their own and perform most tasks as competently as
individual insects of more solitary species: red invasive
fire ants, each with their own powerful stings that can
be used multiple times, provide a good example of this
competence (Holldobler and Wilson 1990). However,
sociality takes an ant’s ability to perform almost all of
these tasks far beyond mere competence. It permits a fire
ant to switch its behavior between two options: to act
alone or to act as super-individuals within their colonies
(Moller 1996). Not only is their niche broadened by their
eusocialty, but ants are alone in this niche: they are the
only eusocial predators occupying the soil and ground
litter (Holldobler and Wilson 1990).
More specifically, some of the additional benefits of a
social life in red invasive fire ants include better dispersal,
higher reproductive rate, greater longevity, a broader niche,
more effective predator defense, enhanced competitive
abilities and a lack of intraspecific competition (Moller
1996). Underlying behaviors behind all of these traits
are communication, cooperation, and division of labor.
A closer look into the mechanics of predator defense
reveals how these behaviors result in such a wide variety
of benefits and function to increase flexibility. Ants can
“communicate with one another about predation risks
encountered within the colony’s foraging range and then
adjust their use of such areas according to feeding rewards
and risks of starvation” (Moller 1996). Also, because the
colony as a whole is the key reproductive unit, only nestcentered predation is a substantive threat to established
colonies (Moller 1996). Death or mutilation of single
ant means little to the functioning and propagation the
super-organism of the colony. This truth is even more
apparent in fire ant colonies where masses of ants resting
or patrolling function as reserves, an activity which
permits “fine-tuning to the inevitable wide shifts that
occur in the requirements of the brood” (Holldobler and
Wilson 1990).
SPRING 2003
Genetic Plasticity, More High-tech Armaments
and the Super-Colony
As if the red invasive fire ants did not already possess
enough firepower and behavioral flexibility, they also have
an history of genetic plasticity. They have undergone two
metamorphoses of particular concern since their arrival
in the United States. The first such genetic alteration was
for greater cold tolerance (James et al. 2002). This new
and improved invader arose from the hybridization of the
black (S. richteri) and red imported species (S. invicta)
of fire ants. S. richteri arrived in the United States before
S. invicta, but has since been largely overwhelmed by
its more vigorous cousins (Taber 2000). The additional
ability of fire ants to withstand temperatures below
freezing would prove catastrophic, since as E.O. Wilson
originally predicted, one of the few (and therefore
important) factors limiting fire ants’ distribution to the
southern States is their inability to tolerate severe cold
(Taber 2000).
The second, perhaps even more serious, genetic
change undergone by red imported fire ants harks back
to one of E.O. Wilson’s original observations that “IFA
[invasive red fire ant] colonies sometimes adopt queens
from outside the nest” (Taber 2000). With this apparently
minor insight into behavior Wilson hit on one of the
most intensely studied topics today regarding fire ants:
the steadily increasing abundance of polygynous and
unicolonial colonies among S. invicta in the USA since
the 1970s (Bourke 2002). Though multiple-queen
colonies do exist in the red fire ants native habitat, they
differ consistently and dramatically “in their social
organization and contain relatively few queens that are
close relatives, whereas colonies in the United States
contain high numbers of unrelated queens” (Ross et al.
1996).
The extreme social nature of the polygynous form
makes it much hardier and more hazardous than the
original monogynous invader. Polygyny takes the concept
of super-individual one step further with the creation of a
“super-colony,” in which the flexibility is amplified. Since
there is no intraspecific territoriality between colonies
this new form of ant is able to exist at densities often ten
times as great as the monogyne form (Porter and Savigno
1990). Such high numbers lead to a much improved
ability to compete against and repel individuals of other
species. Porter and Savigno report that polygynous ants
are more capable of wreaking havoc on an ecosystem
and decimating native ants than are their monogyne
predecessors (1990). Perhaps, most alarmingly, polygyny
increases the ants invincibility to human attack since “the
presence of two or more queens seems to help colonies
recover from an attack by pesticides” (Unlimited Pain
2000). In polygynous colonies, if one queen is killed there
is still another to keep producing more fire ants.
25
MONOGYNOUS COLONY
POLYGYNOUS COLONY
Queen number
One
Many
Genotype of queen(s)
BB
Bb
Queen phenotype
High fat reserves, rapid oogenesis
Low fat reserves, slow oogenesis
(advantageous under monogyny)
Worker phenotype
Invasion of the Red Fire Ant:
Bb workers tolerate multiple queens, but
A Multi-layered Metaphor for
only if they bear the b allele; Bb workers
Managing Invasion through the
detect and kill BB queens; all bb quenns
Study of Behavior BB workers in
(and workders) die early because b is a
absence of
recessive lethal.
Bb workers are intolerant of
multiple queens
Table 1. Genetic and phenotypic traits of monogynous and polygynous colonies in introduced Solenopsis invicta fire ants (Bourke 2002).
If the consequences of the spread of the polygyne
form are as disagreeable as they appear, the question
for invasion biologists attempting to look into the
future becomes: why is it increasing in frequency
and can the tide of increase be stemmed? The answer
can only be discovered through an interdisciplinary
approach combining genetics, behavior, and the ecology
surrounding S. invicta. In a noteworthy paper, Krieger
and Ross found a rather simple feature underlying a
fairly complex behavior (1998). They established the
genetic basis of gyny variation in fire ants and pinpointed
the shifting of two alleles (B and b) at a particular locus
(see table 1). According to Krieger and Ross, all fire ants
known to be polygynous contain b-like alleles, while
those that are monogynous only have the B allele (1998).
In discovering the often searched-for bridge between
genetics and social behavior, molecular biologists have
demonstrated the true complexity of this invasion and
developed predictive models. As to whether they are
any closer to stopping the spread of polygynous ants
is debatable. Herein lies the problem with a behavioral
approach: each time the picture gets more complete it
also becomes more complex. Even so, it is the best weapon
humans currently have in their conflict with fire ants.
Ravages of Invasion
Long before the fire ant invasion, the often
overwhelming effects of ants on an ecosystem were
known. It does not necessarily take a lifetime devoted
to the study of myrmecology to learn that ants “alter
their physical environment profoundly” (Holldobler and
Wilson 1990). The fire ant has more than lived up to this
billing. In an aptly titled article “When Fire Ants Move In,
Others Leave” looking at the impact of an invasive species
on a broad ecological scale, Elizabeth Pennisi reports that
S. invicta severely disrupts the gradient of ant species
across the East Coast of the United States (2000). Biologist
expected to find an increase in the number of ant species
26
with decreasing latitude (diversity tends to increase closer
to the tropics) and they did in all places except those
where the red invasive fire ants were present. Here, native
ants were either locally extinct or very rare. In a much
smaller scale study, limited to a single field, Porter and
Savigno determined that competitive replacement is the
primary mechanism behind the decimation of native ants
(1996). The fire ant also directly (through predation) and
indirectly (through induced behavioral changes) disrupts
arthropod, invertebrate and vertebrate communities;
of particular concern are the many endangered species
negatively affected by S. invicta (Forys et al. 2001).
Such an overpowering invasion can only end in the
simplified environment in which S. invicta becomes the
dominant population regulator. This domination and
simplification, in turn, might lead to complete ecosystem
collapse or greater susceptibility to invasion.
Human Fortifications
The only hope for humans in their battle against red
invasive fire ants is management and control. Recently,
several good candidates for this purpose have been
brought forward, including a microsporidian disease
(Thelohania solenopsae), a parasitic ant (Solenopsis
dagerri), and probably the most promising candidate to
date, a parasitic phorid fly (Pseudacten curvatus) (Lockley
1996). Essential to the implementation of any of these
agents of biocontrol is a thorough behavioral analysis of
the interactions between them, their hosts, and the rest of
the ecological community. For example, Oi and Williams
show that the introduction of the disease T. solenopsae
chronically debilitates S. invicta queens (2002). Studies
on S. dagerri have found that this workerless, social
parasite redirects fire ant workers to its own brood to the
detriment of the colony’s larvae (Lockley 1996). Porter’s
analysis of behavioral risk is so exhaustive as to address P.
curvatus’s possible negative effects on agriculture and on
native ants (2000). Based on observations of fly behavior,
DARTMOUTH UNDERGRADUATE JOURNAL OF SCIENCE
he concludes that it poses only a small risk. However, even
this limited risk needs to be balanced against “potential
benefits to numerous other native organisms and a high
probability that release of this fly will actually benefit
native fire ants because impacts on imported fire ants will
almost certainly be much greater than those on native fire
ants” (Porter 2000).
In spite of the optimism generated by Porter’s study
and the subsequent release of phorid flies, humans
should not begin their victory dances across abandoned
fire ant mounds too soon because there is always the
chance that fire ants will return. This possibility was the
main concern of Oi and Williams , who suggested that
“long-term suppression of S. invicta populations under
field conditions may be dependent on increasing the
ratio of infected to uninfected colonies and/or limiting
the rate of reinfestation by uninfected colonies” (2002).
Because of their invincible social nature and many modes
of rapid dispersal, once fire ants gain a foothold they are
almost impossible to extinguish or expel. Even Porter
qualifies his results with the statement, “A concern is that
no one has ever successfully used classical biocontrol
agents against any social insect” (2000). Such reservations
bring into question what management and control really
entail. In the end, behavioral studies of biocontrol agents
in the laboratory can provide invasion biologists with
predictions only up to a certain point. After that, scientists
must take the leap of faith necessary to introduce the
control agent and continue their experiments on a much
larger scale in which post-control field observations
become of paramount importance.
Combating the Enemy Within
Matters of control are further complicated by fire ants’
close relationship with humans. In fact, many biologists
have observed that fire ants thrive in exactly the areas
from which we are trying to eradicate them (Forys et al.
2001). Walter Tschinkel, a biologist with a good grasp of
insect behavior, provides a definitive opinion on the issue:
“The fire ant is clearly and dramatically associated with
ecologically disturbed habitats, created mostly by man. .
.It is abundant in old fields, pastures, lawns, roadsides, and
any other open, sunny habitats. It shares these habitats
with many other ‘weedy’ plant and animal species . . .
Man is the fire ant’s best friend’” (Brouwer 2000). This
“friendship” is dependent on two main aspects of human
interaction with the environment. First, transport by
humans, including the movement of colonies with mated
queens in plant nursery stock or construction fill and
transportation of newly mated queens in vehicles and
even ballast tanks, creates a dispersal corridor for fire
ants (Forys et. al 2001, Taber 2000). Second, the result
of human disturbance is a habitat with reduced native
predators and competitors that can be easily colonized by
SPRING 2003
human commensals or early succession species such as
the fire ant (Forys et al. 2001). Solenopsis Invicta’s affinity
for human habitats adds to both the element of futility
and of hope in the fight against fire ants, for the success
or failure of a management program is largely dependent
on how we behave.
Not only do fire ants seek human company, it is no
secret that these ants are mirrors of ourselves in many
aspects of their social behavior and in their effects on an
ecosystem. E.O Wilson recognized this truth and took
much of what he learned in his years of studying ants and
applied it to humans in books such as, On Human Nature
(1978). Consider the homogenization of the environment
by fire ants greatly amplified; that is an idea of what the
future could hold in store should humans continue their
current destruction of habitat and not attempt to control
and prevent invasions. The picture of the earth converted
into a giant fire ant mound should be reason enough for
why “refuge, beauty and interest, and security” (Elton
1958) are worth fighting for. Luckily, unlike fire ants, we
are not so genetically programmed in our actions and
tasks that we do not have behavioral flexibility to alter
our damaging ways and provide the possibility for a
better future, less full of fiery stings.
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Vinson, B. (1994). Impact of Invasion of Solenopsis Invicta (Buren)
on Native Food Webs. Exotic Ants: Biology, Impact, and Control of
Introduced Species. ( D.F. Williams, Ed.). San Francisco: Westview P.
Wilson, E.O. (2002). Only Humans Can Halt the Worst Wave of
Extinction Since the Dinosaurs Died, available at http://raysweb.net/
specialplaces/pages/wilson.html.
FACULTY: Have an undergraduate working in your lab? Has a
student of yours produced an especially well-written class paper?
Encourage him or her to submit to the DUJS.
28
DARTMOUTH UNDERGRADUATE JOURNAL OF SCIENCE
The Self: The Cruise Control of
Social Interaction
CAROLINE TARNOK ʻ02
Introduction
During the last hundred years, the self has become an
increasingly important topic of research in psychology.
Although it has been studied extensively and should
be a subject with which we are personally familiar, the
actual nature of the self is still widely debated. Given
the number of subtopics that have arisen and the paths
that this research has taken, Higgins asserts the value of
adopting an explicit perspective on the self and exploring
the implications of that perspective (1996). In this paper,
I develop an evolutionary framework of the self based on
the idea that we rely on others in our social groups for
protection and reproduction. I propose that the self is a
false exterior created by the brain. It is a system that exists
to facilitate presentation strategies, which in turn secure
an individual’s place in society. Higgins presents the idea
of a self-digest that summarizes a body of information
about the individual for the purpose of serving selfregulatory functions (1996). My theory embraces the
idea of the self as a survival tool, but I hypothesize that
the self functions not to regulate an individual’s role with
respect to the general environment, as Higgins states, but
with respect to other individuals.
Evolutionary Background
Dawkins puts forth several ideas that might help
explain an evolutionary view of the self. The first idea is
that of the selfish gene. He maintains that “. . . we, and all
other animals, are machines created by our genes. . . . Our
genes have survived, in some cases for millions of years,
in a highly competitive world. This entitles us to expect . .
. that a predominant quality to be expected in a successful
gene is ruthless selfishness” (1989). Animals, as the carriers
of these genes and having evolved by natural selection,
also exhibit selfish behavior. A selfish act is defined as an
act that increases the chance of survival of the agent, no
matter how slim, and regardless of whether or not it is to
the advantage of others (Dawkins 1989). This idea says
nothing about the motives of the individual; it simply
implies that animals act so as to increase the survival
prospects of their genes.
In order to propagate our genes, however, we must not
only protect ourselves, but also succeed in reproduction.
This struggle for existence includes being dependent on
the environment and on other beings (Darwin 1859).
SPRING 2003
Human ancestors were social beings, and membership
within the complex group structures probably aided
survival. Improved predation, defense against predators,
and defense against rival groups were all beneficial for
these individuals, who may have been “underequipped
to deal with their environment” (Sedikides & Skowronski
2000). As in other animal groups, members differ in
social status, where those of higher status have access to
more resources and higher-quality mates. To propagate
their genes, then, humans and other animals rationally
(although not necessarily consciously) strive to maintain
or advance their status within the group (de Waal 1998).
In humans, I propose that the Self developed to facilitate
the self-presentation that this position-maintenance
requires.
The Evolution of the Self
Other animals are also able to self-regulate in
response to the environment, albeit using simpler and
more automatic mechanisms. Still, they influence others’
opinions of themselves and engage in social protection
and reciprocation. Yet we do not say that they have a self
in the same way that humans do. The key difference may
be that the social structures of lower animals are less
complex, with status often being more obvious within a
comparatively stable hierarchy.
Sedikides and Skowronski argue that only humans
developed a symbolic self, which includes the mental
representation of one’s traits, executive functions, and
reflexive potential (2000). This self was the outgrowth
of (1) a general evolution in cognitive capacity due
to environmental changes and (2) the evolution
of a complex, flexible social structure. The second
development was arguably the crucial antecedent for the
self humans possess today. Other animals can determine
their current social standing with relative ease. With a
more complex and flexible social organization, however,
it is much more difficult for an individual to determine
his status at any one time. In addition, it is even more
difficult to determine—and remember—the status of
others with whom he will need to interact (Sedikides &
Skowronski 2000). Facing numerous and complex costbenefit analyses that would require more brain power and
time than is typically available, an organism would benefit
from developing automated agendas and scripts as soon
29