they are separated from their caregivers. By the pre-
school years, children are able to identify emotions in
others and can seemingly empathize with the feelings
of others, as reflected, for instance, by a three-year-
old bringing his tearful mother his teddy bear to com-
fort her. Although toddlers are interested in other
children, friends typically do not become important
until the early school years, at which time children
enter the peer group and establish dominance hierar-
chies, often based on physical strength, especially
among boys. Typically during this time, boys and girls
segregate themselves into same-sex play groups. In
adolescence, the peer group becomes increasingly
important (although the family rarely loses its influ-
ence), and, coupled with the onset of puberty, hetero-
sexual interests and behavior commence.
A milestone approach to development provides
a quick glimpse at important acquisitions that chil-
dren over the world experience. There is still much
variability in when children attain these milestones,
because of both biological (genetic) and environmen-
tal (societal) factors. And many culturally important
phenomena that arise only with specific experiences
(e.g., reading, religious practices) are not captured by
knowledge of milestones. Nonetheless, milestones
show what is universal in human development and
give parents and educators an idea of how quickly
children are progressing relative to a species-typical
standard.
See also: STATES OF DEVELOPMENT; THEORY OF
MIND
Bibliography
Belsky, Jay, Lawrence Steinberg, and Patricia Draper. ‘‘Childhood
Experience, Interpersonal Development, and Reproductive
Strategy: An Evolutionary Theory of Socialization.’’ Child De-
velopment 62 (1991):647–670.
Bogin, Barry. Patterns of Human Growth, 2nd edition. Cambridge,
Eng.: Cambridge University Press, 1999.
Wellman, Henry M. The Child’s Theory of Mind. Cambridge, MA:
MIT Press, 1990.
David F. Bjorklund
Jesse M. Bering
MISCARRIAGE
Miscarriage is a synonym for ‘‘spontaneous abortion’’
or ‘‘spontaneous pregnancy loss.’’ A miscarriage oc-
curs because of an abnormal fetus (usually within the
first twelve weeks) or disruption of the uterus as a safe
environment (more prevalent after thirteen weeks).
Miscarriages are common, occurring in up to 19 per-
cent of pregnancies.
Miscarriage usually leads to vaginal bleeding, ab-
dominal cramping, and occasionally severe pelvic
pain as the disrupted fetus and placenta pass through
the cervix. The major concerns are the health of the
mother; there are no medical interventions that will
mitigate against fetal death.
Miscarriages are unanticipated and occur early
during a time of frequent maternal ambivalence re-
garding the pregnancy. Grief is often prolonged, with
self-reproach as to the cause of the miscarriage. Sib-
lings usually experience turmoil due to various com-
binations of previous jealousy of the pregnancy, lack
of parental emotional availability, and processing the
reality of death.
See also: BIRTH; PREGNANCY; PRENATAL
DEVELOPMENT
Bibliography
Reindollar, Richard H. ‘‘Contemporary Issues for Spontaneous
Abortion: Does Recurrent Abortion Exist?’’ Obstetrical and Gy-
necological Clinics of North America 27 (2000):541–554.
Scroggins, Kathleen M., William D. Smucker, and Adarsh E. Kris-
hen. ‘‘Spontaneous Pregnancy Loss: Evaluation, Manage-
ment, and Follow-up Counseling.’’ Primary Care 27
(2000):153–167.
Simpson, Joe L. ‘‘Fetal Wastage.’’ In Steven G. Gabbe, Jennifer R.
Niebyl, and Joe L. Simpson eds., Obstetrics: Normal and Problem
Pregnancies, 3rd edition. New York: Churchill Livingstone,
1996.
Michael StorrMITOSIS
Mitosis is the stage of the cell cycle at which chromo-
somal division occurs. This division precedes cytoki-
nesis, or cell division, which leads to two daughter
cells with identical nuclear DNA content. Between mi-
totic events, chromosomal DNA is replicated during
the synthesis stage of the cell cycle. The process of mi-
tosis is required whenever a somatic cell divides. In
contrast to meiosis, which occurs in germ cells prior
to the reproductive process, mitosis does not involve
exchange of DNA between homologous chromo-
somes or a reduction in DNA content.
See also: MEIOSIS
Bibliography
Oak Ridge National Laboratory. ‘‘The Science behind the Human
Genome Project.’’ Available from http://www.ornl.gov/hgmis/
project/info.html; INTERNET.
David W. Threadgill
Robert E. BoykinMONTESSORI METHOD
The Montessori Method is a system of education
based on the beliefs of Maria Montessori. The most
critical components of her method include the pre-MONTESSORI METHOD 275