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 the 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:
the four bases:
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.
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.[youtube]http://youtu.be/MdTCj9tC1Pw[/youtube]
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.
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.
A professional horseman for over 50 years, Skook continues to work with horses. Skook has finished an historical novel, Fifty Thousand Years, that traces a mitochondrial line of DNA from 50,000 years ago to the present. The story follows a line of courageous women, from the Ice Ages to the present, as they meet the challenges of survival with grit and creativity. These are not women who whimper of being victims, they meet the challenges of survival as women who use their abilities without excuses or remorse, these women are winners, they are our ancestors.
Fifty Thousand Years is available in paperback and e-book, it is getting great reviews. You can purchase a copy here; Visit me on Facebook.
Since I moved to Utah I have met plenty of people deeply involved in genealogy.
Mostly this is because of the inbreeding of all the early pioneer families who founded the Utah Mormon population.
Their genetic weaknesses lead to loads of congenitally deaf and also Down Syndrome adults nowadays, so genealogies are now often run before marriage.
But the funny thing is how many of them claim to be able to trace their family back to Adam!
Is it just me, or does that last picture up there look like Debbie Blabbermouth-Schultz? 😉
@Jim+S: Careful, Jim… if this gal reads that, she’ll have her feelings hurt.
@Nanny+G: That is interesting, but the concept of Adam must be placed in an arbitrary time slot. The majority of humans wandered out of Africa in small migration waves, beginning approximately 60,000 years ago. The Neanderthals and Denisovans preceded them. It is hard to imagine these people having names or recording genealogy through an oral tradition. (Historical records would take 55,000 years to be invented.)
Were these primitive groups monogamous or did they breed when they were overcome with the urge to have sex and willing to mate with whomever was available. The truth is buried in many generations and tribal cultures varied widely. In warlike cultures women are regarded as commodities, captured, worked, bred, and sold among warriors. Our Democrats see women as a voting demographic that can be manipulated and bought for a price, again this complicates our fanciful notions of our noble ancestors. Two hundred years ago, most of our ancestors lived in squalor, living with their livestock in crude hovels during winter to stay warm. It is not hard to imagine life two thousand years ago, 20,000 years ago to 60,000 years ago. When the average life expectancy was 34 years, it is hard to imagine these people recording their lineage orally for tens of thousands of years, when survival was a daily struggle.
It would be interesting to see how people account for the Neanderthal and Denisovan DNA content within their own DNA. If they know, please let me in on the secrets.
@Bill: I don’t think she could read, but she could probably knock you out without much effort.
So if they analyze the DNA of killed terrorists, do they find any goat markers?
@Buffalobob: I think the Islamists are hoping for hybrid vigor. It’s a long shot, but they have nothing to lose.
I wonder if the story of Adam and Eve is not the remains of some ancient oral tale… a sort of universal cultural artifact. I understand that many ancient cultures have tales of a great flood, understandable since rivers were so important. Perhaps the story of Cain taking a wife in the land of Nod is a remnant of some earlier tale of inter-species hanky panky. 😉
@Jim+S: I don’t want to rile up the religious, but in those early days, there were many floods and diseases, many tribes were annihilated by disasters. There were probably many instances of a solitary figure from each sex starting up from what was once two different clans. There were very few people in these early days; it is easy to surmise the Adam and Eve story repeating itself many times over 50,000 years. These two people who may have only been the sole survivors in an area the size of Germany, would be regarded as the first humans by later generations. In time, a myth becomes fact.
Could be. I thought that it looked like a younger version of her.
Skook, I enjoyed the presentation – very well done.
It underlines how extraordinarily rapid our growth in numbers has been, to well over 7 billion people — from just a sprinkling of tribes sparsely populating Africa – and we’re all interconnected.
What are we accelerating to? What’s this leading us toward, and why do our egos have so much difficulty learning from history, even from an hour ago?
@James Raider: The population explosion is an explosion. We seem to think we have the ability to find the technology to feed the people of the world, but through man’s relatively short lease on the world, many have perished during famine and drought. It might not happen in our lifetime but in terms of earth’s time, it is just around the corner. Man’s insatiable lust for reproducing will be his undoing. Sadly it is those with the least of everything who are the most prolific breeders, and they expect the rest of us to rake care of their mistakes. it’s a fool’s game we are playing and the time for paying the dealer is getting closer.
When the lifespan was between 30 and 40, and back a short time ago when only 50% of infants grew into adults, it was hard for populations to grow beyond their abilities to care for themselves, but through science and benevolence we eliminate all the natural barriers that are natural safeguards to population explosions. Now we are rushing troops to fight Ebola in West Africa; yes, it seems noble but is this a natural safeguard for overpopulation. You can bet those governments have spent plenty on munitions and ignored basic health care infrastructure. Thus our troops must be exposed to the deadly virus, because a dictatorship didn’t invest in its own healthcare. Who needs healthcare when you can buy weapons.
I am surprised that no one accused me of being an infomercial for the National Geographical program. I did it and I must write, it was enlightening and entertaining. Te science of DNA is proving we are all related and that humans were once great walkers, but it is fascinating to trace the treks of your ancient relatives through time. There will be many surprises for people, that’s a given; unfortunately, some of us don’t want to be confronted with the truth. Believing myths can make life more comfortable.