Human Development

OBJECTIVES:

After studying this chapter, the students should be able to:

1. Know the interrelationship between heredity and the environment in human growth and development.

2. Appreciate the significance of pre-natal development to post-natal development.

3. Identify the different aspects of development.

4. State and explain the principles of heredity.
5. Understand the different stages of development that an individual will pass through.

I. THE BEGINNING OF LIFE

DEVELOPMENT:
Is a process that continues from conception to death.
It is a process of a life-span from a single cell through late adulthood, and is influenced by the interaction of heredity and environment THREE MAJOR PATHS OF HUMAN DEVELOPMENT:
Physical development:
Changes in bodily appearance and structure, with changes in bodily activities like motor skills. Psychosocial development Includes changes in social and emotional aspects of personality. Cognitive development  Changes in the thought processes that could affect language, learning abilities, and memory.

Qualitative changes
Refer to a progressive series of change leading to improvement like those changes in kind that distinguish an infant who have underdeveloped motor skill from a baby who can walk already. Quantitative changes

Refer to the measurable changes in an individual like changes in height, body proportion, and the like. Quantitative changes referred to as growth though growth may be used interchangeably with development. Two factors of development:

Nature: Is responsible for cognitive aspects such as mental capacities, innate traits and other materials that contribute to development as passed upon generations through heredity. Nurture: Is associated with environment that provides the stimuli for nourishment and proper development of certain organism.

II. HEREDITY AND ENVIRONMENT
Heredity
Is a process whereby traits of parents are handed down to their offspring via the genes Environment
Refers to all the forces that affect man, like physical forces, natural forces, and social forces. This also includes the internal environment while the organism is still within the womb

III. Role of Maturation and Learning in Development
Maturation is the gradual unfolding of hereditary traits and potentials. It is the process which the individual has to pass through before he reaches the state of maturity. Maturity marks the end of growth and development.

Phlyogenetic functions  are common to the race like sitting and walking , and development occurs through maturation

Ontogenetic functions
Traits specific to the individual like swimming and writing are learned through training

III.MECHANICS OF HEREDITY
Before the human being is to be conceived, an egg cell or ovum from the mother must be fertilized by the sperm cell from the father. A brand new life begins with the fertilization of the egg cell. Both the mother and the father contribute an equal amount of heredity to the new individual. One half of the necessary number of chromosomes comes from the mother and the other half from the father Chromosomes:

Are thread-like or rope-like bodies that CONTAIN THE GENES.
Are either classified as autosomes or trait chromosomes and gonosomes or sex chromosomes. Genes Are the real bearers of hereditary traits. Dominant traits are strong genes; the trait that dominant genes carry will always be manifested in the offspring. Recessive genes are the weak genes; the trait that a recessive gene carries can only be manifested if it is paired with another recessive gene of its kind. IV. SEX DETERMINATION

The sex of the offspring depends on the pairing of the sex chromosomes form the mother and the father. If the zygote or fertilized egg received an X from its mother and another X from its father, the offspring will be a girl. If the zygote receives an X from a mother and Y from the father, the offspring is a boy

V. PRINCIPLES OF HEREDITY
1. Principle of reproduction
– states that “Like begets like”, where human individuals will reproduce their own kind.

2.Principle of Variation
States that “NO” two individuals of any kind are exactly “ALIKE” even identical twins have mild differences like one could be slightly taller that the other.

3. Principle of Dominance and Recessiveness

This principle determines the presence of similarities and differences among family members. There are traits assured of appearing in the child, WHENEVER PRESENT – these are known as DOMINANT TRAITS. Other traits that are recessive appear only in the ABSENCE OF A DOMINANT TRAIT.

4.Principle of Chance

The hereditary endowments and the number of births are played by chance alone. Which millions of sperm cells will fertilize the ripened egg cell is attributable to chance alone. 5. Principle of Sex-Linked Characteristics

These sex-linked are carried by the same genes that determine sex. Carried by women but, usually suffered by most men. For instance, baldness, color blindness, and hemophilia are sex linked characteristics. IV. HEREDITARY CHARACTERISTICS

1. Physical traits
The appearance in general like facial features, complexion, height, and body built. Physical defects are characteristics like harelip, cleft-palate, and stub-finger. Physical diseases – predisposition to tuberculosis, asthma, and hypertension. 2. Mental traits – examples are I.Q level, some cases of mental retardation, and predisposition to mental disorder. 3. Special talents/Abilities – Like artistic, literary pieces, athletic, musical, and numerical talents. VIII. MULTIPLE BIRTHS