HUMAN DEVELOPMENT

Human development – the study of the human over the life span

Genes – our biological blueprints

Many of our characteristics are determined at the moment of conception, when 23 chromosomes on the egg pair up with 23 chromosomes on spermGenotype – all information stored in genesPhenotype – observable characteristics

The likelihood of traits being expressed can be worked out with a Punnett Square

Chromosomes contain DNA, which is made up of 1,000s of genes (total of ~100,000)•Each gene is a self-replicating segment of DNA capable of synthesizing proteins

•Genes are composed of NUCLEOTIDES – a linear sequence of structural units that form DNA – these biochemical bases combine to form 3 billion pairs that determine your individual biological development

The nucleotide base letters are:•A adenine•C cytosine•G guanine•T thymine

Some Genetic Abnormalties:

1. Turner’s Syndrome – X - karyotype

Sterile, limited secondary sex characteristics, short “webbed” neck 1 in 2,500 live births

2. Klinefelter’s Syndrome – XXY karyotype

Sterile, tall, small testicles, passive, reclusive 1 in 1,000 live births

3. Jacob’s Syndrome – XYY karyotype

Tall, lower mental ability, high level of testosterone1 in 1,000 live births

4. Super female – XXX karyotype

No specific abnormalities 1 in 1,000 live births

Webbed neck

5. Edward’s Syndrome – Trisomy of 18th chromosomeSevere mental retardation, most die in infancy6. Down Syndrome – Trisomy of 21st

chromosomeMocaism – some do not have the abnormality in every chromosome; affects level of mental retardation and expression of characteristics

WHO ARE THE PERFECT SUBJECTS FOR STUDYING HUMAN DEVELOPMENT?

•Identical twins

HOW DOES PSYCHOLOGY STUDY HUMAN DEVELOPMENT?

•Twin studies, adoption studies, temperament research, heritability studies

Monozygotic twins: Dizygotic twins:

Twin studies show remarkable similarities in intelligence, temperament, stress response and rates of mental illness**Most ideal twins? Identical twins separated at birth – offer both nature and nurture opportunity for study

3 major issues researched by developmental psychologists:

1. Nature vs. nurture2. Stability vs. change3. Continuity vs. stages

PRENATAL DEVELOPMENT:

•Female is born with 500,000 O ocytes – cells with potential to develop into ovum. 10,000 remain at puberty and approx. 400 will be ovulated in a lifetime•Male begins producing sperm at puberty, and produces it for the rest of his life

One ejaculation contains 200 to 400 million sperm!!The odds against you being you are billions to one!

When is a female most fertile and likely to conceive?

**14 days from the start of her last period

Conception occurs! Newly fertilized cell is called a zygote

Stages of Prenatal Development:

1. Germinal Period – Conception through 14th day•Ends when zygote implants into the

wall of uterus (or cells are sloughed off)

2. Embryonic Period – 2nd through 8th week

Development is cephalo-caudal (from the head to the trunk)

Critical period of pregnancy (though entire pregnancy is important) – time when environment can have the greatest effect on the organism

6 week embryo

3. Fetal Period – 9th through 40 weeks 20 week fetus

Development shifts to Proximo-distal (from trunk outward to limbs)

Teratogen – agent that can cause damage to embryo/fetusMost infamous teratogen:thalidomide

Age of viability – time when fetus has a 50 – 50 chance of survival if premature: 24 weeks

24 week premie

THE NEWBORN:

Reflexes: sucking

rooting

grasping

stepping

Babinsky

Moro

Infant intelligence:

Recognize mother’s voice

Recognize mother’s milk

Prefer faces to patterns

Imitate facial expressions at 2 weeks

Physical Development:

Motor milestones of the first 2 years:

1-2 weeks Turns head to follow moving object6 weeks Rolls from stomach to back3 months Rolls from back to stomach6-7 months Sits alone for 1 minute8-9 months Crawls10 months Says da da8-10 months Walks while holding on to something12 months Takes first steps14 months Walks alone, says several words18 months Climbs stairs, says many words18-24 months Runs, combines two words24 months Puts on shoes

**All require biological maturation

Cognitive Development:

Jean Piaget’s Theory of Cognitive Development

Child develops thinking abilities through stages as their SCHEMAs grow and change

Schema – framework for organizing information

•New information fits easily into schema sometimes - assimilation•New information requires a change of the schema - accomodation

1. Sensorimotor Stage – 0 to age 2

Babies understand their world through their senses and motor activities

Abilities they develop:

* Object permanence – an understanding that objects exist when no longer visible

* Stranger anxiety

* Language develops

•All take place at age 8-9 months

2. Preoperational stage – ages 2 through 6

The child is EGOCENTRIC – cannot take another person’s point of view

The preoperational child loves to :pretenduse animismuse artificialism

3. Concrete Operations 7 - 12

The school aged child now uses LOGIC

•Egocentrism, animism and artificialism break down•Concrete (not abstract) types of activities such as multiplication and division are possible

•Conservation – the understanding that quantity remains the same regardless of shape

•The concrete operations child rejects the magical beliefs in Santa, tooth fairy, etc.

4. Formal Operations 13 and up•The child can now use ABSTRACT reasoning

•Abstract math and science are possible

•Interest in world affairs, religion and politics increase

**Critics of Piaget say all of the ages in the stages should begin earlier**

Self-concept Development

Babies recognize themselves by 15 months

Social Development

ATTACHMENT – intense infant love for caregiver

It lies at the heart of the nature vs. nurture issue

•Studied by Harry Harlow

•Baby rhesus monkeys were raised in individual cages, away from mother with fabric for a blanket

•They were distressed when he took the fabric out to wash it; he thought about what it meant

•It made him question the conventional idea that babies attach to mothers because they provide food

He created surrogate figures: one covered in cloth, the other with a bottle

The babies became very attached to the cloth-covered figure

He called this need for soft, loving contact CONTACT COMFORT

Good news for dad – he can provide contact comfort too!

Another key to attachment: familiarity

Konrad Lorenz discovered a rigid attachment process in animals:

•The bird followed him like he was the mother

•He made himself the first thing baby geese or ducks saw after hatching

IMPRINTING

He also identified a critical period for imprinting

Mary Ainsworth studied mothers and toddlers - mothers left toddlers in room for a few minutes, how did child respond?

Parenting styles and attachment:

She identified 3 types of attachment:

1. Securely attached – child explored around mom, cried when mom left, joyous when she returned2. Insecurely attached – child was clingy, cried when mom left, angry when she returned

3. Avoidant – little contact between mother and child

Could this foretell the relationship patterns of a lifetime??