Principles of Psychology
Dr. Emiliana Simon-Thomas
The scientific study of human development seeks to understand
people – all kinds of people everywhere – change, and also
how they do
change, from conception until death.
• Perspective is multidirectional (change occurs in every
direction – not just in a line), multicontextual (different life
circumstances, historical (
), SES, etc.
(values, traditions, ethnic group), multidisciplinary (biology,
sociology, neuroscience, anthropology, economics, history,
All living things are
made up of tiny
The molecules of
, which contain all of the
Altogether, the packet of instructions is the individual’s
Each cell has 46 chromosomes (23 pairs), each chromosome in organized into
The human genome – about 30,000 genes.
Male and female
each contain 23 chromosomes (1/2 as
many as other bodily cells).
When the sperm penetrates the ovum, it migrates towards the ovum’s
nucleus, their nuclei fuse, and thus become a
This genetic info, 23 chromosomes from mom and 23 from dad
constitute an individual’s
Most genes pair up well, except the 23
Dad’s cells have XY
and mom’s cells
Therefore, ova always have an
X at 23, and sperms have an X ½ the time
and a Y ½ the time.
The sex of the offspring: XX at 23 - girl,
XY at 23 - boy.
Identical/Monozygotic (one zygote splits) vs. Fraternal/Dizygotic (two ova,
Comparing mono and dizygotic twins is useful a useful method for
investigating genetic contributions to development.
Most traits are
additive genes &
, I.e. the
Sex-linked genes/X-linked genes
: males are more susceptible, I.e.
genes: e.g. secondary sex characteristics.
Genetic diversity & variation: