Posted by Skook on 23 September, 2014 at 8:22 am. 12 comments already!


DNA The Basis for All Life

DNA The Basis for All Life

The story of mankind is essentially a story of migration and of reproduction of the species. In the past we relied on archaeological evidence and fossils to tell us of early man, but fossils are limited, because of the conditions required to preserve bone in a fossilized state.

Most organisms, including man are preserved as fossils when death occurs near a water source and the subject is buried in alluvial silt or mud within a short period of time. The encased bones are protected from the elements and scavengers by this protective covering of soil that often turns into rock. Over time, the bones decay and the organic cells are replaced by mineral accumulation, a process termed petrification. The bones may also decay completely leaving a void within the media. This negative cast of the bones will accumulate minerals to form a stone replica of the original specimen.

Because of the special requirements needed to form fossils, the fossil record is incomplete and of limited scope in analyzing the story of man. However, DNA, the basis for all life, is unlocking the secrets of man and his journey through time and over the globe.

A brief history of genetic research:

The study of genetics originated with a Roman Catholic monk, Gregor Mendel, in 1857. He studied mathematics at imagesthe University of Vienna and later worked with pea plants (pulses or legumes) over an eight year experiment. His experiments set the stage for the concept of inheritance and the science of genetics. Mendel is considered the father of genetics.

Friedrich Miescher (1844-1895) discovered and named a material he named “nuclein” in 1869. He later isolated a sample of nuclein from the sperm of Salmon, nuclein later became known as DNA. One of his students, Richard Altmann called the material “nucleic acid” and determined it was only found in chromosomes.

in 1928, a scientist, Fredrick Griffith, was working with pneumonia and mice to prove the DNA molecule the vehicle for inheritance. He had two strains of pneumonia, virulent and non-virulent. The virulent strain was fatal: the non-virulent strain allowed mice to survive.

By heating the virulent strain, he could neutralize the lethal effect and a mouse would survive after the injection. He finally injected both the heated and non-virulent strains and the mice died.

Griffith surmised the neutralized strain had passed on a characteristic to the non-virulent strain to make it virulent. He termed this inheritance characteristic, transformation.

Oswald Avery took Griffith’s experiments a step farther to isolate the inheritance factor. In turn, he destroyed the lipids, ribonucleic acids, carbohydrates, and proteins of the virulent strain of pneumonia, but the transformation was still occurring. He finally destroyed the deoxyribonucleic acid and transformation was halted. He had found the basis of inheritance.

In 1929, Phoebus Levene identified the components of the DNA molecule:images

the four bases:
Adenine (A)
Cytosine (C)
Guanine (G)
Thymine (T)


Levene mangaged to demonstrate that the components of DNA linked in the order phosphate-sugar-base. He maintained the units were nucleotides and suggested the DNA molecule was a string of nucleotide units linked through the phosphate groups. He felt they comprised a backbone for the molecule. Unfortunately, he assumed the segments were short, with a repetition throughout the bases. Torbjorn Casperson and Einar Hammerstein proved DNA to be a polymer or a molecular structure consisting of a large number of similar units bonded together.

During the 1940’s, Edwin Chargaff determined a pattern within the four bases: adenine, guanine, cytosine, and thymine. The DNA of different cells was found to have two constants among the bases: the adenine amount is almost equal to the amount of thymine and the amount of guanine is almost equal to the amount of cytosine. The constants A=T and G-C became known as Chargaff’s Rule.

Rosalind Franklin and Maurice Wilkins formed DNA inro a crystalline form to obtain an x-ray photo to determine a pattern. The result portrayed the DNA molecule as being in the shape of a twisted ladder with two parallel strands or helixes ( a helix is a curved three dimensional curve i.e. a coil spring or cork screw. DNA’s formation has two intertwined helixes.)

Watson and Crick built a model of the DNA molecule in 1953, from the x-ray of Franklin and Wilkin. This model is still accepted as the DNA structure, with only slight alterations.images

The model is a double helix with rungs of nucleotides connecting the two strands. They paired the constants of Chagraff’s and found the molecule to be uniform. They determined a hydrogen bond between the two pairs of bases and each side to be a compete complement of its partner.

In 1984, DNA profiling was developed by English geneticist Alec Jeffreys. In 1988, genetic profiling of DNA was used to convict a murderer in England.

Although conclusive DNA evidence was produced at the 1995 murder trial of OJ Simpson, the accused murderer was found innocent.

The Simpson Trial represents a miscarriage of justice; however, it ended the public’s skepticism of DNA profiling in America.


From the mid-19 Century work of Gregor Mendel, to the public disgrace of the OJ Simpson Trial took 150 years, but in the last twenty years our knowledge of DNA and of man’s presence on earth has grown exponentially.

We now know through DNA profiling the approximate eras of migrations out of Africa, and yes, man originated in Africa.

Science can now trace personal DNA back in time to 60,000 years ago, when our first ancestors began migrating out of Africa. There were two other distinct species of hominids who migrated out of Africa during this same period: the Neanderthal and the Denisovan. The title ‘distinct species’ is by the old definition impossible, since a separate species cannot breed with another, and when cross breeding occurs as in the case of a jackass and a horse mare, the offspring is sterile. However, the genetic traces and markers are present in people whose ancestors left Africa during this migration period. Most people who left Africa and walked the Eurasian landmass are composed of a genetic grouping of slightly more than 2% Neanderthal and slightly less than 2% Denisovans. Unless you adopt the attitude of the OJ jury, the evidence is in your DNA. My personal DNA was slightly unusual, since it recorded a 3.4% of Neanderthal concentration and zero influence of the Denisovan strain.

Individually, we are given a timetable through distant ancestors and the movement of their descendants. A study of migratory paths that lead to the present, from a marker of your oldest ancestor through successive generations and migrations.

We all carry a unique DNA code that is a composite of genes from both out maternal and paternal lines. This DNA will determine genotypical traits like eye color, hair color, and vulnerability to disease. The Y chromosome is passed from father to son, unchanged through generations of a male line. Mitochondrial DNA is passed from mothers to their children, but only daughters can transmit Mitochondrial to the next generation.


An Unattached Young Female Spots A Possible Mate From Another Tribe

The male and female DNA continues unchanged, until a mutation (a random change, usually harmless) occurs. The mutation is described as a marker and can be mapped through generations over thousands of years.

When a marker is detected, its origin is traced back through generations and geographical locations. Every marker becomes a new branch on man’s family tree. Tracking the lineage of these markers provides the movements of individual tribes through tens of thousands of years.

It is important to remember, the process of mate selection over time was complicated by whether tribes sought mates from outside the tribe and whether the tribe was of a maternal or paternal organization and whether a man or a woman was supposed to join up with the tribe of a mate or whether the males were more modern and impregnated females and moved on with no familial instinct.

The markers within your DNA have recorded your lineage through generations as your ancestors migrated over the inhabitable regions of the earth.

The science is new and as more genetic markers are identified, more details of individual donors will be identified and related to individuals through personal accounts with the National Geographic Project. In other words, there may be a slight variation as new data is recorded and discovered, allowing for a greater understanding and increased accuracy.

0 0 votes
Article Rating
Would love your thoughts, please comment.x