Understanding why and how
The science of human development:
- The science that seeks to understand how and why people of all ages and circumstances
change or remain the same over time
- growth over the life span is multidirectionalm multicontextual, multicultural, multidisplinary,
- development depends on theories, data, analysis, critical thinking and sound methodology
The Scientific Method
- A way to answer questions that requires empirical research and data based conclusions.
1. Ask a question
2. Develop a hypothesis (a specific prediction that can be tested.)
3. Test the hypothesis. Design and conduct the research to gather empirical evidence.
a. Empirical evidence: evidence based on data from scientific observation or experiments,
4. Draw conclusions. Use the evidence to support or refute the hypothesis,
5. Report the results. Share the data, conclusions and alternative explanations.
- Replication- repeating the procedures and methods of a study with different participants is
often a 6 and important step. Conclusions are revised, refined and confirmed after replications.
The nature- nurture controversy
- Nature - the influence of the genes that people genetically inherit from both parents.
- Nurture- the influence of ones environment
- It turns out that neither beliefs are entirely accurate. The question is “how much” not “which
one” , becomes both genes and the environment affect every characteristic
- Epigenetics- the many ways environmental forces alter genetic expression.
Sudden Infant Death
- The term used to describe an infant’s unexpected death, when a seemingly healthy baby,
usually between the age of 2 and 6 months olds, suddenly stops breathing and dies
unexpectedly while asleep.
- Susan Beal, noticed an ethnic variation: Australian babies of Chinese descent died far less
frequently of SIDS than did Australian babies of European descent.
- No genetic relation to SIDS
o because the Chinese babies laid on their backs and not on their stomachs like the
o back sleeping protected against SIDS.
- other risks to SIDS are: low birth weight, a brain stem abnormality that produces too little
serotonin, cigarette smoke in the household, soft blankets and pillows and bed sharing in their
parent’s beds The life-span perspective
- The life-span takes into account all phases of life, not just the first two decades (childhood and
- In this perspective age periods are only a rough guide line to “change over time” and this is
particularity apparent in adulthood.
o 18-25 is considered emerging adulthood
o 25-64 is adulthood
o 65 years and older is late
Development is multidirectional
- When human traits are charted over time, its apparent that some traits appear, disappear,
increase and decrease and zig-zag over the life span.
- Traditionally, the idea is that all development advances until the age 18, steadies and then
declines, but this has been refuted.
- characteristics can be continuous, discontinuous or even don’t change over time
o each characteristic follows a distinct pattern.
Example: when babies begin to talk, they lose the ability to distinguish sounds
from other languages.
- Critical period: A time when a particular type of developmental growth (in body or behaviour)
must happen if it is ever going to happen.
o Example: the human embryo grows arms and legs and feet and fingers and toes each
over a critical period between 28-54 days after conception, after that it is too late. Life
has very few critical periods.
- Sensitive period- a development that usually occurs around a certain time period but can be
o A time when a certain type of development is most likely to happen or happens most
easily, although it may still happen later with more difficulty.
Example: early childhood is considered a sensitive period for language learning.
If children do not start speaking their first language between the ages of 1 and
3, they might not so later, but their grammar is usually impaired.
o Every case is different and there can be fully unimpaired cases
Development is multi-contextual
- It can take place within many contexts including physical surrounding, (climate, nise, population
density) and family configurations (married, couple, single parent, extended families).
- Urie Bronfenbrenner recommended that developmentalists take an ecological-systems
approach or bioecological theory (the person should be should considered in all the context and
interactions that constitute a life)
- This approach recognises 3 nested levels that surround individuals and affect them.
o Microsystems –each person’s immediate surroundings, such as family and peer group.
o Exosystems –local institutions such as school, and church, and external networks, such
as employment o Macrosystems –larger social settings, including cultural values, economic policies and
o Mesosystems –refer to interactions among systems, such as parents and teachers
coordinating to educate a child
o Chronosystem – the dimension of time and how that changes and affects other systems
- Obviously, a contextual approach to development is a complex one and many contexts need to
The historical context
- Cohort: a group defined by the shared age of its members, who, move through life together,
experiencing the same historical events and cultural shifts.
- Ages 18-25 are a sensitive period for consolidation of social values; experiences during emerging
adulthood have a lifelong impact.
o Example: attitudes about war and society differ for the US cohorts who were young
adults during WW1, the conflicts in Vietnam, the Persian Gulf, Iraq and Afghanistan or
during the war on terrorism.
- Cohorts can really reflect the historical contexts
o Example: the cohort born between 1946-1964, called the baby-boom generation
because it represented a sizeable spike in the birth rate. Because of this, they will
experience quite a different because there is so many of them. This is especially true in
the Western nations, where the birth rate was very slow during the Great Depression
and WW2. This cohort is already affecting policies regarding social security
The Socioeconomic Context
- Reflected in a person’s socioeconomic status or SES (a person’s position in society as
determined by income, wealth, occupation, education and place of residence)
o A US family is composed of an infant, an unemployed mother, and father who earns
$15,000 a year. Their SES would be low if the father was an illiterate dishwasher in the
slums, but it would higher if the wage earner is a postdoctoral students living on campus
and teaching part time,
- Income alone does not define SES, especially when one considers the historical context
o Who qualifys to lives above or below the poverty depends on many factors that are still
- When compared to the traditional measures, the revised definition finds increase rate of
poverty among people (1) who live in cities, (2) who were born outside the US, (3) who are
Asian, (4) who pay taxes or (5) who are olders than 65.
- SES brings advantages and disadvantages, opportunities and limitations, all of which affect
housing, health, nutrition, knowledge and habits.
o Although low income obviously limits a person, other factors are also important. Annual
wages are inadequate to measure wealth.
Childrens learning is affected by family assets
- the US the gap in life expectancy between rich and poor has been increasing over the past
decades. This could be related to better health and nutrition and less stress. Development is multicultural
- all cultures must be included
- Culture- a system of shared beliefs, norms, behaviours and expectation that persist over time
and prescribe social behaviour and assumptions.
o Social construction- an idea that is based on shared perceptions, not on objective
o They affect how people think and behave and what they value, ignore, and punish.
- Each family, community and college has a particular culture and these cultures make clash.
- Often people use the word culture to refer to large groups of people such as Asian culture, or
Hispanic culture. But this invites stereotyping and prejudice, since large groups of people like
those, can include people from many cultures.
o There are differences in Korean and Japanese cultures even though they may both be
considered Asian cultures. For this reason, the word culture needs to be used carefully.
Deficit or just different?
- People tend to think that their nation and culture are a little better than others. This belief can
become destructive if it reduces respect and appreciation for others.
- difference-equals deficit error: the mistaken belief that a deviation from some norm is
necessarily inferior to behaviour or characteristics that meet the standard.
- This concept is one reason a multicultural approach is necessary.
o Various ways of thinking or acting is not necessarily wrong or right, better or worse. We
need empirical data for accurate assessments.
o For example, cultures that discourage dissent also foster harmony. But the opposite is
also true in the fact that cultures that encourage dissent also value independence. A
multicultural understanding requires recognition that some differences signify strengths
Learning within a culture
- Lev Vygotsky noticed that parents of the Soviet Union taught their children whatever beliefs and
habits they might need as adults.
- He believed that guided participation is a universal process used by mentors to teach cultural
knowledge, skills and habits.
o Guided participation can occur via school instruction but more often happens
informally, through mutual involvement.
Ethnic and Racial Groups
- People of an ethnic groups share certain attributes, almost always including ancestral heritage
and usually national origin, religion and language.
o Some people of a particular ethnicity differ culturally, and some cultures include people
of several ethnic groups
- Ethnicity is a social construction, affected by the social context, not a direct outcome of
biology. This means it is nurture not nature.
o Example: African-born people who live in North America typically consider themselves
African, but African-born people living on that continent identify with a more specific
ethnic group. o Ethnic identity becomes strengthened and more specific when other of the same ethnic
group are nearby and when members of other groups emphasize differences.
- Race is also a social construction- by a misleading one.
o Race –a group of people regarded as a distinct from
- Most beople believe in catigorizing race based on physical differences, particularly outward
appearance. Most North Americans believed that race was real, an inborn biological
characteristic. Races were categorized by colour: black, white, red and yellow.
o Social scientists now believe that race is a social construction and that colour terms
exaggerate minor differences.
o There are no Genetic differences within these “races”
Skin colour is misleading because dark skin people who ancestors were not
African have `high levels of genetic population diversity and because dark skin
people whose ancestors were not African share neither culture not ethnicity
o Race is a destructive concept. The concept of Race was used to justify racism which was
used with slavery lynching and segregation.
o labels encourage stereotyping, and labeling people by race leads to the notion that
superficial differences in appearances are significant.
- Need to bring confidence to those who have been told in the past that their race is below others
o Particularity in adolescences, people who are proud of their racial identity are more
likely to do better in school, resist drug addiction, and have higher self-esteem.
Development is Multidisciplinary
- Human development requires insights and information from many scientists, past present, in
many disciplines. The understanding of human development really benefits from research from
many different disciplines.
Genetics and Epigenetics
- Genetics came into play after he human genome project happened
- Genes do affect every aspect of behaviour, but even identical twins with identical genes, differ
biologically, socially, and psychologically.
- all important human characteristics are epigenetic. This refers to the effects of environmental
forces on the expression of an individual`s genetic inheritance.
o Some epigenetic influences that occur impede development, such as, injury,
temperature change, drug abuse and crowding. But some influences facilitate
development such as, nourishing food, loving care, and active play.
- Epigenetic research is especially important in treating diseases that impair the brain and
devastate human development.
o the brain contains an epigenetic `hotspot` with a unique potential to not only better
understand its most complex functions, but also to treat its most vicious diseases
o Genes are always important, some are expressed, affecting development, and some are
never noticed from generation to generation. Multidisciplinary research on depression
- depression is partly genetic and neurological, certain brain chemicals make people sad and
uninterested in life.
- there is no doubt that depression is developmental, it increases and decreases throughout the
o For instance, clinical depression usually rises in early adolescence, particularity among
females. Throughout life, whether or not a person becomes depressed is affected by
chemicals in the brain, not only by neurotransmitters such as dopamine and serotonin,
but also by growth factors such as GDNF (glial cell line-derived neurotropic factor), the
product of one gene that makes neurons grow or stagnate.
- Child-rearing practices also have an impact of depression as well.
o depressed mothers smile and talk to their infants less and in turn the infants become
less active and verbal. Depressed 1 year olds tend to become much happier by age 6 if
their mother`s mood had lifted.
o Physiological, psychological and social data showed that the mother`s depression
throughout early childhood had a major impact.
Children of the mother whose depression decreased were less aggressive
- Nature is affected by nurture. A person with depressive relationships and experiences is likely to
develop the brain pattern characteristics of depression.
o At least 12 factors are link to depression, some are:
Low serotonin in the brain (neuroscience)
Childhood caregiver depression (psychopathology)
Low exposure to daylight as in winter in higher latitudes (biology)
Malnutrition, particularly low hemoglobin (nutrition)
Family history of eating disorders (genetics)
o Each of these factors arises from research in a different discipline (the disciplines are in
the brackets). Making a multidiscipline approach crucial in alleviating every type of
Development is plastic
- The term plasticity denotes two complementary aspects of development: human traits can be
molded and yet people can maintain a certain durability of identity.
- A view of human development as an ongoing, ever changing interaction between a person`s
physical and emotional being and between the person and every aspect of his or her
environment, including the family and society.
- Plasticity cannot erase a person`s genes, childhood or permanent disabilities, but experiences
can give people lifelong strength. Nurturing parents and family, a comprehensive education to
help with the disabilities, are just some ways that someone with disabilities can change and
improve their lifestyle. Differential sensitivity
- Plasticity has emphasized that people can and do change and that predictions for people are not
always accurate. 3 insights about human development have improved predictions:
o Nature and nurture always interact
o Sensitive periods more affect by particular events than others and differential sensitivity
aids prediction and intervenes more quickly. People are sensitive to different things
because of genes.
Differential sensitivity - The idea that some people are more vulnerable than
other are to certain experiences, usually because of genetic differences
- Generally scientists have found that genes or circumstances, that both ways – they predispose
people to being either unusually successful or severely pathological.
11 year old African American boys in rural Georgia. When they hit puberty it is a
sensitive time when young teens seek to rebel against parents and teachers,
and when the allure of booze and, pot and sex is strong. But if a young boy can
resist these hazards until he is more mature, his future will be much brighter.
They had a seminar for ½ the boys on rules and stuff
The first follow up 5 years later, was disappointing. The intervention didn’t have
an effect, both groups drank, smoked and had sex at similar rates. They
assessed whether each boy had the short or long version of a particular gene, 5-
This difference in genes was very important. Those with the long version
developed just as well whether they were in the intervention group or not, but
those with the short version who attend the seminar were less likely to have
early sex and use drugs than those who also had the short version who didn’t
have the intervention.
The sensitivity provided by nature (the difference in genes) allowed the special
nurture (the intervention) to have an