Benefits of DNA technology
Before we go further, let us consider some of the direct benefits of modern day DNA technology. Growth in DNA technology research has exploded the last two decades - moving from classical genetics to nanotechnology (the engineering of functional systems at the molecular scale).
The production of human vaccines and the application of gene therapy will soon be routine rather than the exception in medical science.
The identity of an individual can be established by matching his DNA and the DNA collected from a crime scene. A signature, in the form of DNA, left at a crime scene, is an irrefutable perfect example of forensic science at work.
The genetic engineering of crops for higher yield and other quality traits, and the production and sale of genetically modified organism (GMO) makes agricultural science on the fore front of biotechnology. Genetic testing provides both preventive (for example breast cancer screening) and preferential screening for the determination of the sex of a child.
The present generation, with emphasis on freedom of choice, cast additional burdens on marriages resulting in over 50% of marriages ending in divorce with increasing parental disputes and child custody cases. DNA based genetic testing is one avenue to resolve disputes arising from child custody battles.
DNA: origin, design and purpose
In order to understand the subject, I would like to touch on some basic information about DNA and genetics. It has been said that God gave humanity two books: the Bible and the genetic codes of DNA.
The Bible provides the blue print for the spiritual man; the genetic codes provide the blue print for the physical man. There are 60 trillion cells in the human body with each cell carrying 23 pairs of chromosomes containing genetic information from both parents.
Each cell is serviced by blood vessels extending 65,000 miles long. Just to understand the complexity of the DNA molecule, let's compare bacteria vs. human beings. There are about 200 genes and 100,000 DNA units that govern a bacterial structure and function.
On the opposite spectrum, there are about 40,000 genes (still in dispute) and 3 billion DNA units in human beings. During the process of human development, these genes are turned on and off at various stages of development.
A process that is this precise and tightly regulated must be error free or spontaneous abortion occurs. Oversimplifying the issue has led to the contention that life is just the product of DNA, but as a creationist, I reject this concept and support the idea that God created organisms fully formed as recorded in Genesis chapter 1.
Human ancestry, behavior, and origin
The human population shares 99.9% of DNA. However, mutations found in the 0.1% that differs can be used to trace ancient genetic ancestry. Since DNA is passed from parents to offspring, accumulated mutations create a genetic family tree that encodes a wealth of information.
Scientists have correlated many of these mutations, DNA markers, in the form of a single nucleotide difference and have reconstructed human migration maps dating back many generations.
The two main techniques currently used are
1) mapping by diverse DNA sequences (polymorphism) on the Y chromosome to trace paternal ancestry, and
2) mitochondrial DNA to trace maternal lines.
Both techniques take advantage of the fact that some genetic material is passed down unchanged from parent to child in the case of the Y chromosome, from father to son; and in the case of mitochondrial DNA, from mother to child (both male and female).
There are some limitations: for example, Y chromosome tracing will connect a man to his father but not to his mother, and it will connect him to only one of his four grandparents: his paternal grandfather.
Likewise, mitochondrial DNA traces the maternal line with limits only to maternal contributions. Whenever an egg cell is fertilized, nuclear chromosomes from a sperm cell enter the egg and combine with the egg's nuclear DNA, producing a mixture of both parents' genetic code.
The mtDNA from the sperm cell, however, is left behind, outside of the egg cell. The fertilized egg contains a mixture of the father and mother's nuclear DNA and an exact copy of the mother's mtDNA, but none of the father's mtDNA.
The result is that mtDNA is passed on only along the maternal line. This means that all of the mtDNA in the cells of a person's body are copies of his or her mother's mtDNA, and all of the mother's mtDNA is a copy of her mother's, and so on.
No matter how far back you go, mtDNA is always inherited only from the mother. If you went back six generations in your own family tree, you'd see that your nuclear DNA is inherited from 32 men and 32 women. Your mtDNA, on the other hand, would have come from only one of those 32 women.
In 1987 Rebecca Cann et al., examined the mtDNA of 147 people representing all continents around the world. Later, with the help of a computer program, they put together a family tree, grouping those with the most similar DNA together, then grouping the groups, and then grouping the groups of groups.
The tree they ended up with showed that one of the two primary branches consisted only of African mtDNA and that the other branch consisted of mtDNA from all over the world, including Africa. Based on this, the most recent common mtDNA ancestor was an African woman.
To be continued...
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* Chong Singsit, Ph. D. contributes regularly to e-pao.net.
The writer can be contacted at singsit(at)earthlink(dot)net .
This article was webcasted on 8th December 2007.
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