Sibling rivalry is a phenomenon that fascinates our culture and
is the subject of fiction and Satellite Movies as well as how-to parenting magazines. Our Evolutionary past sheds some light on the world of sibling relationships-
why some siblings exhibit altruistic behavior and some exhibit
a ongoing competitive attitude. Parents want to prevent their
offspring from developing antagonistic especially in our culture
today, where small successful families have replaced large ones.
From examining our Evolutionary tendencies and psychological studies, I have gathered that
one strategy in preventing sibling rivalry is large birth spacing.
A major factor, however, in sibling relationships (in an Evolutionary perspective) is also the reSources available to the siblings, and logically the more reSources there are, the more children can be thrown together with minimal
conflict. On the other hand, smaller reSources would accommodate few successful, peaceful offspring, and large
birth spacing would facilitate this situation.
I am conducting a Study to test the resource size, family size and birth spacing to understand
the conditions under which large birth spacing would be beneficial.
I assert that siblings with large birth spacing and low reSources will dramatically less sibling rivalry than those with low reSources and small spacing. On the other hand, siblings with large parental
reSources and small spacing will still be more rivalrous than those with
larger spacing, but not so drastically as those families with
small reSources. If this turns out not to be the case, our Evolutionary need for parental reSources is overshadowed by social and cultural influences on sibling
relationships
Theoretical Background
The Research behind this claim begins with Hamilton’s law of kin selection
that is still being tested and studied by scientists. His premise
is that your sibling has half of your genes, so you are more likely
to help him/her than someone unrelated to you, but you will help
yourself first. This can be expressed in the following equation:
c < br
c= the cost of altruistic behavior
b= the benefit to kin of altruistic behavior
r= the percent of relatedness (for human siblings r= .5) (Wright
170)
One recent study on this theory revealed how in a certain population
of salamanders in which one will occasionally break out and start
eating his neighbors, this cannibal morph appeared less often
and later in a tank made up relatives. Also, in tanks of mixed
families, the morph would eat its non-kin before its kin. This
illustrates how inclusive fitness works and what makes sibling
relationships so complex (Gonnick 124).
The question remains: How do we use this basic principle for kin
relationships to make environments that lower the cost of altruism,
and therefore maximize altruistic feelings. From examining ethnographic
and psychological studies of sibling relationships it seems that
when siblings are spaced far apart, the older sibling takes on
a socializing/caregiving role that curbs rivalry. On the other
hand, closer spaced siblings form more intense bonds and more
intense conflicts.
Many of these studies are cross-cultural examination of sibling
behavior. Patricia Zukow, for example, studied low-income Mexican
families, and came to the conclusion that, “Siblings act as socializing
agents throughout the world” (Zukow 80). Another study examined
the Kwuarua culture in the south Pacific islands. This study revealed
how important older sibling were in giving child care, and there
sibling rivalry was practically non-existent (Gregeo 75).
Large birth spacing makes a big difference in how children react
to these roles of teacher and novice. One psychological study
rated the playing of sibling pairs with varying age differences
by its effectiveness in socialization. Topics like “linguistic
skills” and “artistic development” were used to distinguish the
types of play, and not surprisingly, the pairs with larger age
differences engaged in more effective play (Bond, Gibbs, and Teti
166-7).
Frank Sulloway supports this assertion that large birth spacing
decreases sibling rivalry in his book, Born to Rebel. While this
book (quoted by Wright), focuses on how the younger sibling can
project his role in the family (fighting into the pre-made establishment)
onto his/her future career and ideology, he also notes how birth
spacing affects this phenomenon. He describes how older sibling
of newborn birds will, with the help of the mother, kick the rookie
out of the nest (Sulloway 133).
His main point deals with how younger siblings find individual
“niches” to gain the attention of parents without going for the
same resource area as an older sibling. Sulloway shows how this
happens more successfully in families of large-spaced children.
While younger siblings generally have more revolutionary mindsets
than their older siblings, this trend was more pronounced in siblings
of differing ages. Large birth spacing can pave the way for siblings
to find their niches more easily (Sulloway 134).
Popular parenting magazines offer the same kind of advice for
stopping sibling rivalry such as not to compare siblings and not
to take sides in a fight. Perhaps a more preventive form help
would be useful considering our tendency to compete with siblings
for resources while protecting them as carriers of half our genes.
Large birth spacing can be worth the reproductive costs for parents
by putting their offspring in a position to help each other with
little cost, and in a position to find successful individual niches.
Method
As I mentioned earlier, I will conduct a survey to test for the
resource size, family size and birth spacing. The results of this
survey constitute the evidence to prove or disprove my hypothesis
I will survey about 40-50 individuals about their family situations.
The first part of my survey will deal with resources which I will
measure by asking about the number of parents in the household
and the household income while growing up.
I will then ask the participants how many siblings they have,
and the differences in the ages. I also want to know if either
the participant or his/her sibling are handicapped or were requiring
special medical attention. Lastly, I want to asses the nature
of the participant’s relationship with his/her sibling. In the
case of multiple siblings, I will ask the participant to answer
questions in terms of the sibling closest in age. This is the
most difficult part of the study, since individuals’ relationships
vary so greatly. The survey will contain questions concerning
the participants memories of playing with their siblings, and
how the relationship has developed into adulthood.
Analysis
This survey should contain about 20 questions, and I hope to show
how resources and sibling numbers and spacing correlate. If my
predictions hold, then the participants with one parent at home,
and small income should show more rivalrous attitudes towards
their siblings and even more rivalrous attitude if the family
is large and the birth spacing small. If their is no pattern in
where sibling rivalry rears its ugly head, then it is mainly an
issue of personality, family, or cultural influence.
I will show my results by putting the factors together on in Stat-view
much in the fashion of the survey at the beginning of the semester.
Bibliography
Gonick, Larry. “Fine Young Cannibals.” Discover. October, 1993. pp. 124-5.
Kent, Debra. “How Even Good Parents Fuel Sibling Rivalry.” Good
Housekeeping.
March, 1997. pp.80-3.
Leder, Jane Mersky. “Adult Sibling Rivalry.” Psychology Today.
January, 1993.
pp. 56-(8 pages).
Samalin, Nancy. “How to Cure Sibling Fights.” Parents. May, 1993. pp. 146-50.
Sulloway, Frank J. Born To Rebel. Pantheon Books: NewYork, 1996.
Teti, Douglas; Gibbs, Elizabeth; and Bond, Lynne. “Sibling Interaction,
Birth Spacing,
and Intellectual/Linguistic Development.” from Sibling Interaction
Across Cultures.
edited by Patricia Zukow. Springer-Verlag: New York, 1989.
Watson-Gregeo, Karen Ann and Gregeo, David W. “The Role of Sibling
Interaction in
Child Socialization.” from Sibling Interaction Across Cultures.
edited by Patricia Zukow. Springer-Verlag: New York, 1989.
Wright Robert. The Moral Animal. Vintage Books: New York, 1994.
Zukow, Patricia G. “Siblings as Effective Socializing Agents:
Evidence From Mexico.”
from Sibling Interaction Across Cultures. edited by Patricia Zukow.
Springer- Verlag: New York, 1989.
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