SOURCE1
The above picture
was taken in 1953 when James Watson (left) and Francis Crick presented their
model of a DNA molecule (deoxyribonucleic
acid model).
They had pieced together pieces of a scientific puzzle that scientists had been
working on for many years. With the discovery of this model a new way of
understanding life began -- humans could understand the basic building blocks
of life for the first time in history.2
Image Source3
DNA
is a double-stranded molecule
that encodes the genetic instructions used in the
development and functioning of all known living organisms and many viruses.4
3,000,000 species share this genetic code. The DNA alphabet consists of four letters that represent the four chemical
bases that make up the rungs of the DNA – A,
T, G & C.
● A
- adenine
● G
- guanine
● C
- cytosine
● T
- thymine
Be
sure to note that rungs are made of combinations of “A and T” or “C and G.” The human genome is
the genetic instruction manual for creating the physical make-up of a human
being. It contains 3 billion letters.
Cells are invisible to the naked eye, but each cell contains about 6 feet of
DNA thread, which means there is about 3
billion miles of DNA in each of us! 5 If we printed out the human genome it would fill a space
equivalent to 800 copies of the Bible.6
A
gene is a specific section of
DNA. Genes are part of chromosomes
and they are found in the nucleus
of cells.
Source 7
Genes
tell cells what to do and when to do it – be
a muscle, make a bone, be a lung, be part of the digestion process, etc.
Human cells normally contain 23 pairs of chromosomes, for a total of 46.
Twenty-two of the pairs are the same in all humans. The 23rd pair is the sex
chromosome and they differ in males and females.
● females have two X chromosomes
● males have one X chromosome and one Y chromosome8
SOURCE9
All
human beings are 99.9 percent identical in their genetic makeup.10 Genetics has
transformed the way we understand physical differences between people. This is
especially important when it comes to conflicts related to gender and skin color,
for example. No one living before the middle of the 20th century could have
been aware of the role DNA plays in creating gender or skin color -- and many people living today do not
understand it.
Human skin color
is quite variable around the world. It ranges from very dark brown to near
yellowish pink. There are no people who actually have true black, white, red or
yellow skin, even though those colors are commonly the only choices we are
given for describing skin color.
SOURCE11
The reason humans have different shades of skin
color is linked to the content of melanin. Deeply pigmented skin has the
highest content of epidermal melanin (the complex molecule responsible for the
pigment in the skin, hair, and eyes). Melanin protects skin by reducing the
penetration of ultraviolet rays into the nuclei of cells where DNA resides.
So why do people say that there are only four
categories of skin color? It is a product of memetics, not genetics. A
paper published
by Carl Linnaeus in 1735 separated people into four
varieties by skin color. Linnaeus erroneously linked skin color to specific
geographical locations and temperaments too. The four categories he created combined physical traits with folk
beliefs, which were mostly just fables.
● white
-- Europeans / sanguine (optimistic,
hopeful, or confident)
● brown
-- Asians / melancholic (depressed or
sad)
● red
-- Native Americans / choleric
(bad-tempered or irritable)
● black
-- Africans / phlegmatic (not easily
upset, excited, or angered).
The first person to formally define “race” was the noted philosopher Immanuel Kant, who in 1785 classified people into four fixed races, which were arrayed in a hierarchy according to color
and talent. Kant, like Linnaeus,
combined physical traits with popular beliefs.
Kant promoted
the rank-ordering of races by skin color
to create a self-evident order of nature
in which light-colored races were superior and destined to be served by the
innately inferior, darker-colored ones.
The preference for light over dark was
derived from pre-medieval associations
of the color white with purity and virtue, and the color black
with impurity and evil. Negative associations of dark skin
and human worth were promoted and increased as the transatlantic slave trade
became more lucrative.12
It is essential to include the above genetic and memetic facts
should be included in discussions that involve skin color or race.
The human
genome reveals
important facts about the role of DNA in gender differences. Scientists noticed
an oddball pair among the homologous chromosomes lined up at the cell equator
during reduction division. The X
chromosome was much bigger than the Y chromosome. In humans, this mismatched pair of one X and one Y chromosome is
seen exclusively in male cells. A matched pair of X chromosomes is
found exclusively in female cells. XX chromosomes determine femaleness and XY chromosomes determine maleness.
Females only produce eggs and males only produce sperm.13 "Sexual dimorphism" is the scientific
term for physical differences between males and females of
a species. Human males and females are more physically similar than different,
but, nonetheless, there are key distinctions in their physical bodies. The above information should be included
in discussions that involve gender.
One
of the latest scientific discoveries related to DNA is that our genes carry
more information than just about how to create specific parts of the body. A
new field in genetics is dedicated to epigenetics.
Like silt deposited on the cogs of a finely tuned machine after the seawater of
a tsunami recedes, certain life experiences, ours and those of our forebears,
are never gone, even if they have been forgotten. They become a part of us -- a molecular residue holding fast to our
genetic scaffolding. According to the new insights of behavioral
epigenetics, traumatic experiences in our past, or in our recent ancestors’
past, leave molecular scars adhering to our DNA. Members of the following groups
have been identified as carriers of epigenetic memories.
● Jews whose great-grandparents were
chased from their Russian shtetls.
● Chinese whose grandparents lived
through the ravages of the Cultural Revolution.
● Young immigrants from Africa whose
parents survived massacres.
● Adults of every ethnicity who grew up
with alcoholic or abusive parents
The
DNA remains the same, but psychological and behavioral tendencies are inherited
through epigenetic factors. You might have inherited not just your
grandmother’s knobby knees, but also her predisposition toward depression
caused by the neglect she suffered as a newborn -- or not. If your grandmother was adopted by nurturing parents, you
might be enjoying the boost she received thanks to their love and support.14
So,
it’s very important to understand where our DNA comes from. One-half of our DNA
came from a male and the other half from a female. In sexual reproduction, the male’s DNA unites with that of the female
to create a new, unique set of 46 chromosomes. This is how an ancestor’s traits
are passed down to descendants. The history of our ancestors is
called a genealogy, which comes from two
Greek words – γενεά (genea), "generation";
and λόγος (logos), "knowledge."
It is important to be aware of the sources from which your DNA came. Discovery
of DNA and the creations of the internet have transformed the field of
genealogy and genealogical research.
Understanding
the biology of human behaviors begins with an awareness of the role DNA plays in
every person’s life. In discussions that involve conflicts, it is important to identify
relevant genetic factors – and make clear
distinctions between the roles genes and memes play.
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12 http://www.theroot.com/articles/culture/2013/02/race_and_skin_color_separating_myth_from_reality/
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