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CHAPTER III HUMAN GROWTH AND DEVELOPMENT When we are young, we think that not only ourselves, but all about us, are immortal. - Benjamin Disreali Ψ The Nature of Development Development is a process that produces a progressive series of changes that are orderly and coherent and which lead to, and end with, maturity. (Hurlock, 1978 ) Ψ Factors of Development A. Heredity and Environment 1. Heredity - the transmission of traits from parents to offspring through the genes 2. Environment – includes all the forces that affect or influence man. B. Maturation and Learning 1. Maturation – unfolding of the hereditary potentials; takes place without any effort from the learner 2. Learning – process of development that occurs through the medium of the environment; takes place through the effort of the learner The Interaction of Heredity and Environment The traits most influenced by heredity include physical features, predisposition to certain diseases, intelligence, sensory acuity, mental disorder and other fundamental abilities and capacities. - for example, heredity is mainly responsible for giving you your particular body build, complexion, eye color and texture of your hair - color blindness and baldness are also hereditary traits - heredity is the chief determiner of mental traits Reproductive Cells The best way to understand the complex interaction of heredity and environment is to begin at the beginning of life, the moment of conception. In each sex the germ cells originate in paired organs called GONADS. Male Gonads - testes Male germ cells - sperms Female Gonads - ovaries Female germ cells - eggs or ova - Both sperm and egg contain 23 CHROMOSOMES each. Structures that carry GENES Carriers of hereditary traits - All other cells in the body contain 23 pairs of chromosomes. The fertilized cell which is known as the ZYGOTE, contains all the hereditary potentials which will later develop into traits. MEIOSIS - process of cell division undergone by the sperm and egg cells - this is when the 23 chromosome pairs are split, re-arranged and distributed to the two daughter cells, each receiving 23 single chromosomes. - during fertilization, these 23 single chromosomes in the father’s sperm will combine with the 23 in the mother’s egg to produce a complete set of genetic information for a new human being. Chromosomes are essentially long, spiral-shaped molecules of a complex substance called DNA (deoxyribonucleic acid). The DNA is a long, ladderlike chain of chemical molecules. The order of these molecules or organic bases, acts as a code for genetic information. They are also known as the code of heredity. A GENE is a small portion of a DNA molecule that contains the code for producing one of the many proteins from which the body is built. Genes are the chemical “blueprints” for building and maintaining a living organism. Principles of Heredity 1. Principle of Reproduction. Like produces like. A pygmy child will resemble his parents. Nature sees to it that the specie or genus breeds true to type, except where there are laws governing such variations. (“Ang santol ay di nagbubunga ng mangga) 2. Principle of Variation. No two individuals of any kind are exactly alike. Sometimes the differences may be small and sometimes very pronounced. 3. Principle of Chance. Within the limits of potential traits transmissible by heredity, chance plays an important role, making absolute predictions almost impossible. Sex is determined by chance. 4. Principle of dominance and recessiveness This principle determines resemblance as well as differences among the members of the family. Some genes are dominant, others recessive. A gene that is dominant will have a way in determining the physical characteristics of an individual, no matter what kind of gene it is united with. A recessive gene must join with one just like itself in order to take effect. For example, the gene for normal vision is dominant, while the gene for colorblindness is recessive; dark hair is dominant, blonde hair is recessive; curly hair is dominant over straight hair. 4. Some traits are sex linked. Color-blindness, hemophilia and baldness are examples of sex linked traits. They are so-called because they are carried by the same gene that determines sex. Another interesting fact is that women carry the sex-linked traits, but they are evident mostly in men. Determination of Sex When and how is the sex of an individual determined? In human species in which sexual reproduction is the rule, nature intended every man and woman to have 46 chromosomes per cell; 22 pairs of autosomes, which determine countless characteristics other than sex, and 2 gonosomes or sex chromosomes. In the female these are a pair of X’s or XX matched chromosome, in the male, XY pair. When a sperm fertilizes an ovum, each supplies half of the chromosomes for the combination of cells that will grow into a baby. If the sperm contains an X chromosome, the baby gets that X plus one X from the mother, the result being an XX, a female. If the sperm contain a Y chromosome, the baby gets that plus and X from the mother, the potent male Y overpowers the single X and the result is an XY, a male. Chromosomal Abnormalities A number of genetically determined disorders are linked to abnormalities of pair 21 of the sex chromosome. Known, for example is mental retardation caused by a lack of specific genes and others by the absence of whole chromosomes. Normally, loss of an entire chromosome results in death. However, there are certain exceptions. Females having a single X chromosome, instead of the normal XX, have the condition known as Turner’s Syndrome, which includes retarded sexual development and visual agnosia, an inability to discriminate or recognize the form of objects. The presence of 3 number 21 chromosomes instead of the normal pair results in down’s syndrome or mongolism. Determination of Twins and Multiple Births Twins - fraternal, identical and Siamese Fraternal or non-identical or dizygotic twin - two ova are in the fallopian tubes at the same time that is fertilized by 2 sperm cells, the chromosomes and genes of the two zygotes from which they are developed are not the same that is why the twins will be dissimilar in physical and mental make-up. They may be of the same sex or have opposite sexes. In reality, fraternal twins are not twins but simultaneous pregnancies. Identical or monozygotic twins - only one ovum is ripen and released, the offspring will be a singleton unless the zygote splits into two distinct parts in the early stages of cell division, they have originated from the same zygote, the offspring from this type of fertilization will have exactly the same assortment of chromosomes and genes and will, therefore, resemble each other in all their hereditary traits and will always be of the same sex. In rare cases, the division of the zygote is incomplete and the result is a pair of SIAMESE twins who may be joined at the buttocks, chest, neck or other parts of the body. Triplets, quadruplets, etc. - Triplets and other forms of multiple births may be tree types: identical, in that all have come from the same zygote; identical or non-identical, where one may be a singleton coupled with identical twins or quadruplets composed of a pair of identical and a pair of non-identical twins; or siblings, each having come from a separate fertilized ovum. Maturation Maturation - is a process wherein development in the individual due to bodily changes is determined by heredity. 3 Characteristics 1. Maturation follows an orderly sequence. 2. In its orderly course, maturation proceeds along a physiological gradient. 3. Maturation is not uniform for all children because of the differences in heredity among individuals; there are noticeable differences in the rate and extent of development. Ψ Principles of Development 1. Development is orderly and follows a sequential pattern which is predictable. The stages that we go through from birth to death are always in the same order This predictable sequence is also observable in the PHYLOGENETIC skills or those skills which are universally true of the species and of the human race. Thus sitting preceded standing and standing precedes walking Two predictable trends in direction of physical development; a] CEPHALO-CAUDAL – development starts at the head region and proceeds downward, ending in the feet. b] PROXIMO-DISTAL – parts of the body nearest to the center are the earliest to develop and the farthest parts the last 2. Development is the product of the inter action of maturation and learning Maturation is a process though which hereditary traits “unfold” at an appointed time as the individual grows older We cannot stop maturation but for it to take place, it needs an adequate and appropriate environment 3. There are INDIVIDUAL DIFFERENCES in development We can predict that after a child is born, he will go though the same stages of development as another child but each child will go through these stages at his own rate which may differ from that of another child 4. Development proceeds by stages There are definite stages of development and each stage has its own characteristic features which distinguish it from another stage. Internal Factors Affecting Development Factors that interfere with normal pattern: a. Mother’s diet. Inadequate diet of the mother has been linked to premature births, increased frequency of disease, and even low intelligence among children. b. Diseases. Disease-producing organisms present in the mother’s blood can sometimes infect the developing fetus through the placenta. German measles, gonorrhea, and herpes produce abnormalities. Diseases such as meningitis, scarlet fever, whooping cough, and pneumonia may leave permanent damage to the central nervous system. c. Drugs. Excessive use of aspirin can harm the circulatory system of the fetus. d. Alcohol, coffee and tobacco. Children born to mothers who ingest alcohol heavily develop fetal alcohol syndrome. This is manifested in retarded growth, damage to the nervous system, and distortions in the shape of the face. Caffeine slows down fetal growth and contributes to premature birth. With regards to tobacco, the effect on fetal growth relates to the number of cigarettes smoked during pregnancy. e. RH Factor. This is caused by the genetic incompatibility between mother and child. Fetal blood from an RH positive baby may get into the bloodstream of an RH negative mother thus producing antibodies that can destroy the baby’s blood system. f. Pollution. Air pollution results in a reduction in birth weight and therefore increases birth mortality. g. Mother’s emotions. Maternal anxiety or anger may cause various hormones to be released in the mother’s blood. These chemicals absorbed by the fetal bloodstream may have bad effects although it is not the chemical but the timing that dictates the abnormality produced. STAGES OF DEVELOPMENT Everyone can observe stages of growth taking place in children from infancy to adulthood. These changes do not come about abruptly; on the contrary, they are the culmination of long periods of slow, almost imperceptible growthchanges that seem quite insignificant from day to day in a child’s life. 1. Prenatal Stage The PERIOD OF GESTATION or prenatal period takes place nine months or 280 days between conception and birth It is divided into three stages: 1. PERIOD OF THE OVUM/ Germinal Period (fertilization to 2 weeks) the fertilized cell implants itself in the wall of the uterus cells have just begun the process of MITOSIS 2. PERIOD OF THE EMBRYO/ Embryonic Period (2nd week to 2nd month) all the important structures and features start to develop and to function the accessory apparatus develop: (1) placenta which is the source of nourishment; (2) the umbilical cord which is the only tangible connection between the unborn child and the mother and which carried the oxygen and nourishment from the mother to the child, and (3) the amniotic sac which houses the fetus and protects it from serious injury during the prenatal period 3. PERIOD OF THE FETUS/ Fetal Period (end of 2nd month to birth) from this time up to birth, the structures that were formed during the period of the embryo continue to grow and develop increased fetal activity is observed like kicking and squirming the unborn child attains VIABILITY, that is the ability to live an independent existence outside the womb, by the 6th or 7th month PRE-MATURE: birth occurring before the completion of 280 days; FULL TERM: birth after completion of the 280 days 2. Infancy Stage It begins at birth and ends when the infant is two weeks old. This is a period of major adjustments, namely: adjustments to temperature, breathing, sucking and swallowing, and elimination. While these adjustments are being made, no development process is apparent. An infant is comparatively helpless and immature. This helplessness and immaturity is important as the basis for learning. The newborn is capable of some reflexes – involuntary protective movements 1. BABINSKI – fanning out of the toes when the sole of the foot is touched 2. DARWINIAN or grasp – the newborn grasps tightly any object placed in its hand 3. MORO or startle – the baby throws out his arms when he is startled, as by a loud sound, then brings them back together to his chest as in an embrace 4. ROOTING – baby turns his head towards the source of stimulation to his mouth area and them makes sucking movements 5. PUPILLARY – baby closes his eyes automatically when a bright light shines on them 3. Babyhood Extends from the end of the period of infancy until the end of the second year of life. This stage is characterized by rapid growth, decrease in helplessness, and an accompanying increase in independence. Babies develop selfawareness. They can relate images in the mirror to themselves and have already some sense of themselves as persons. At about 2 years old, they can respond discriminatory to different members of the family. 4. Early Childhood Extends from 2 to 6 years of age. It is the period of the life span when the major development is that of control of environment. It is also called the “preschool stage” because it is the period preceding the entrance into school. It is characterized by ‘questioning, negativism, and aggression’. The child also begins to notice sex differences at this age. 5. Late Childhood Extends from the age of six to the onset of puberty between 11 to 12 years. It is marked at the beginning by the child’s entrance into school, a milestone that is responsible for many of the changes that take place in his attitudes and behavior during this period. This stage has been called the “smart age”, when the child thinks he knows everything and does not hesitate to inform others. This is also called the “gang age” because the major concern of the child is his gang and the desire to be accepted dominates his behavior. Other considerations during the stages of babyhood and childhood: Children differ from each other. Some develop faster and further than others. Although hereditary factors may be partly responsible, much of the difference seems to be related to environmental factors such as the amount of intellectual stimulation they receive at home, parents’ education, stability of the parents’ marriage, and wealth. Emotional Development - generally, excitement is the only emotion that newborns can express and this can be aroused by any stimulus to which the infant responds with mass activity. Gradually, the responses become differentiated into two – reactions to the pleasant and unpleasant. The emotions that dominate his childhood will influence his temperament and this, in turn will affect his personal and social adjustment. Language Development – The first form of language a child uses is CRYING. COOING – the baby makes many kinds of sounds produced through chance movements of the vocal chords and have no meaning. BABBLING – the baby makes sounds which are combinations of vowels with consonants (ba, ma, da) The socialization process is very important to the development of language Learning to speak is achieved largely through the process of modeling Ψ Social Development – the real core of social development is found in the emotional attachment or close emotional bond, that babies form with their primary caregivers. A direct sign that an emotional bond has formed appears around 8 to 12 month of age. At this time, children will display separation anxiety (crying and signs of fear) when she is left alone or with a stranger. Ψ Maternal and Paternal Influences – Life with Mom and Dad for the first few years of life, caregivers are the center of a child’s world. This makes the quality of mothering and fathering very important. Parenting Styles – Psychologist Diana Baumrind studied the effects of three major styles of parenting a. Authoritarian Parents - enforce rigid rules and demand strict obedience to authority - instant obedience for them is the most desirable child trait - when there is any conflict between parents and children, no consideration is given to the child’s view, and no attempt is made to explain why a child is not permitted to doing what he wants; and often the child is punished for even asking - children of authoritarian parents are usually obedient and selfcontrolled. But they also tend to be emotionally stiff, withdrawn, apprehensive and lacking in curiosity b. Overly Permissive Parents - give little guidance, allow too much freedom, or don’t hold children accountable for their actions - take a tolerant, accepting view of their children’s behavior, including both aggressive and sexual urges. They rarely use punishment of make demands of their children. Children make almost all of their own decisions - the child has rights similar to an adult’s, but few responsibilities - permissive parents tend to produce dependent, immature children who misbehave frequently. Such children are aimless and likely to “run amok” c. Authoritative Parents - supply firm and consistent guidance, combined with love and affections. They respond to their children’s needs and wishes. Believing in parental control, they attempt to explain the reason for it to their children. - Authoritative parents expect mature behavior and will enforce rules, but they encourage their children’s independence and search for potential. They try to have their youngsters understand that both parents and children have rights. - they control their children’s behavior in a caring, responsive, nonauthoritarian way - this style produces children who are competent, self-controlled, independent, assertive and inquiring 6. Early Adolescence Extends from 13 or 14 to 17 years of age. It begins when the individual becomes sexually mature or the onset of puberty. This varies from individual to individual, and between the sexes, and also differs from culture to culture. It is a period wherein marked changes occur in duties, responsibilities, privileges, and relationships with others. This period is characterized by instability, unhappiness, awkwardness of movement, strong emotions and curiosity about sex. 7. Late Adolescence This stage is recognized at age 17, when the individual has attained recognized status in school and in the home, and ends when he is at the age of 21, when he has reached legal maturity that enables him to assume his status in adult society. This period is characterized by greater stability. Impulsiveness and emotionality gradually tone down. The body has fully developed proportionately and the movements are more refined and this gives a considerable degree of happiness. The curiosity about sex is being replaced by congenial heterosexual companionship. This narrows down the circle of friends because of social discrimination. Facts about adolescence: The term adolescence comes from the Latin “adolescere” which means “to grow to maturity” It is the transition from childhood to adulthood The period begins with puberty and ends with maturity In some cultures, adolescence is a “happy and carefree” time; in others it is a “stormy period” characterized by insecurity, unhappiness and instability. In many western countries, the age seems to be characterized by a struggle for independence from parental and adult domination Adolescence is the period of seeking self-identity; this self-concept develops gradually starting from childhood Physical Development: o Puberty is the time when the sex organs mature and boys and girls become capable of reproducing their kind o With genital development, the boy produces mature sperms and the girl, mature ova. o In girls, this is signaled by the coming of the MENARCHE, the first menstrual flow; in boys the equivalent could be NOCTURNAL EMISSIONS (seminal flow), also called ‘WET DREAMS’ o At the same time, both boys and girls develop certain adult physical characteristics which are typical of their sex known as SECONDARY SEX CHARACTERISTICS o BOYS: grows hair on the face (upper lip and chin); skin coarsens; shoulders broaden, muscles become heavy and firm o GIRLS: grow rounded hips and enlarged breasts; voice mellows o These physical changes are mainly due to the action of the endocrine glands, more specifically the pituitary gland which is responsible for growth in height and the gonads which brings about the secondary sex characteristics 8. Adulthood This period extends from legal maturity, 18 to approximately 40 years of age. Certain changes occur in the latest part of this period, which mark the beginning of physical and psychological decline. At this stage an individual is ready to assume the duties and responsibilities of an adult and his behavior will conform to the approved pattern of the adult in his culture. This period is characterized by 3 adjustments: (a) adjustment to work (b) adjustment to marriage, and (c) adjustment to parenthood. The degree of success he will when he reaches the peak during middle age will determine how happy he will be in the later period of his life. The years of later adulthood are generally highly productive ones in which people take pride in their accomplishments. 9. Middle Age This stage extends from the age of 40 to 60 in the life span. The onset is marked by physical and mental changes, which accompany the cessation of the reproductive capacities of both man and woman. This is the peak period in life not only for financial and social success, but also for authority and prestige. Oftentimes, middle-aged individuals have to adjust to physical changes, which are difficult to accept and thereby cause anxiety. With this change in life, there is also a change in interest although inflexibility will dominate. Middle age is the period of synthesis---welding together past experiences into a meaningful whole. Many middle-aged people experience a mid-life transition in which they set new and more realistic goals or change their behavior to realize their old goals. They realize suddenly that life is half over and the opportunity to achieve goals is rapidly fading. For men, this is truly the prime of life. While men in their 50’s become increasingly mellow and relaxed, women become more ambitious, self-disciplined and independent. MONOPAUSE: occurs at an average age of 51, monthly menstruation ends, and a woman is no longer able to bear children’ the level of hormone estrogen drops – sometimes altering mood or appearance CLIMACTERIC: occurs in some 40-60 year old males; some men testosterone drop enough to cause symptoms such as depression, anxiety, irritability and insomnia 10. Old Age As individuals enter their 60’s, many pass through another life transition. Some view coming retirements as disturbing especially if there is a sharp drop in income, loss of friends at work, and find themselves responsible for aged parents and dependent grandchildren. This age is the period that has the potential to be most enjoyable, but for few this becomes an unhappy prelude to despair. You may believe that people over 65 are ill, poor, unable to function in society, and mentally deficient. In fact all of these are false. True, physical abilities do decline with increasing age but if these individuals remain active and they engage in regular physical exercise, they can be strong and mentally alert for many more years. Retirement comes between the ages of 60-70. People adjust to retirement in different ways. For a few, senility sets in. they become eccentric, careless, absent-minded, socially withdrawn, and poorly adjusted. Many may enter this final period with most of their cognitive abilities largely intact. Many authors suggest that to live well, we must somehow cope with death anxiety and find some sense of meaning, purpose, and value in life. Aging BIOLOGICAL AGING refers to age related changes in physiological functioning Peak functioning in most physical capacities reaches a maximum by about 25 to 30 years of age. Thereafter, gradual declines occurs in muscular strength, flexibility, circulatory efficiency, speed of response, sensory acuity and other functions Reactions to impending death (by Elisabeth Kubler-Ross) 1. denial and isolation 2. anger 3. bargaining 4. depression 5. acceptance References: Bucu, Luz C. et.al. Introduction to Psychology, 2nd edition. Philippines: Rex Bookstore. 2000. Gaerlan, Josefina. et.al. General Psychology, 5th edition. Philippines: Ken, Incorporated. 2000. Dacey, John S. & John F. Travers. Human Development Across the Lifespan, 4th edition. USA: The McGraw-Hill Companies, Incorporated. 1999.