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Sunday, 29 April 2012

Evolution : Most Interesting Solved Riddle From the time of Darwin to the Modern Age of Genetics.

Early Picture of Genesis From Bible: Adam, Eve and Tree

In early days science is dominated by the church, therefore all people belief that all animal are created by holy God. The almighty God created every animal including  human in a single day .They believe that all modern animal and human are present in a same state from the day of creation.

In early days science is dominated by the church, therefore all people belief that all animal are created by holy God. The almighty God created every animal including  human in a single day .They believe that all modern animal and human are present in a same state from the day of creation.
Anatomical Similarities of Limbs of Different Animals
But after anatomical study of forelimb of different mammals and bird like Human, Dog, Horse,Bird and Bat shows similarity among the limbs, which is not natural, because according to the Bible all animal are unique and different from each other and remain unchanged throughout the time span. This similarity shows the gradual modification of the forelimb from bird to human. This  observation can only explained by the concept of gradual modification or evolution.
Embryological Similarities among the Frog ,Chicken and Human
Another study shows the striking similarity among the Frog, Chicken and Human only at embryo level after that they are very much different from each other which also give another support to the concept of evolution.

One of Cuvier`s contemporaries viewed the fossil record differently.Jean-Baptiste Lamarck believed that life had been created long ago in the simple state. He Believed further that it gradually improved and changed into complex level of organization. The force for change was a built-in-drive for perfection, up the chain of being. The drive was centered in nerve fibers, which directed "fluida" (vaguely defined substances) to body parts in need of change (in a manner unspecified.

 For instance, suppose the ancestor of the modern Giraffe was a short necked animal.Pressed by the need to find food, this animal constantly stretched its neck to browse on leaves beyond the reach of other animals. Streching directed fluid to its neck,making the neck permanently longer.The slightly stretched neck was bestowed on offspring, which stretched their necks also. Thus generations of animals desiring to reach higher leaves led to the modern giraffe.Conversely , a vestigial structure was an organ no longer being exercised enough.It was withering away from disuse, and each newly withered form was passed on to offspring. Such was the Lamarckian hypothesis of inheritance of acquired characteristics.

Lamarck`s Theory on Giraffe

The notion that changes acquired during an individual`s life are brought about by environmental pressure and internal "desires", and that offspring inherit the desired changes.

Lamarck`s Giraffe

Lamarck`s contemporaries considered the hypothesis a wretched piece of science, largely because Lamarck habitually made sweeping assertions but saw no need to support them with observations and tests. In retrospect, perhaps we can find kinder words for the man.His work in zoology was respected.And he did indeed piece together a foundation for an evolutionary theory: Species change over time, and a environment is a factor in that change.

It was his misfortune that he made some crucial observations but came up with a hypothesis that has never been supportable by tests.



Charles Darwin was to develop an evolutionary theory that has had repercussions troughout Western civilization.His early environment may have influenced that destiny.His grandfather, a physician and naturalist, was one of the first to propose that all organisms are related by descent.Being from a wealthy family darwin had the means to indulge his interests.When he was 8 years old he was an enthusiastic but haphazard shell collector.At ten he focused on the habit of insects and birds.At fifteen he found schoolwork boring compared to the pursuit of hunting,fishing and observing the natural world.
Picture of Dairy of Darwin
Darwin`s  Notebook
At college, Darwin attempted to study medicine.He abandoned the study after realizing he never could practice surgery on his fellow humans, given the crude and painful procedures available. For a while he followed his own inclination toward natural history.Then his father suggested that a career as a clergyman might be more to his liking, so Darwin packed for Cambridge.His grades were good enough to earn him a degree.But most of his time was spent among faculty members with leanings towards natural history. It was the botanist John Henslow who perceived and respected Darwin`s real interests. Henslow arranged for him to take part in a training expedition led by an eminent geologist.Henslow arranged that he be offered the position of ship`s naturalist aboard H.M.S Beagle.

Voyage (Path) of The Beagle

The Beagle was about to sail for South America to complete earlier work on mapping the coastline.Prolonged stops at islands, near mountain ranges, and along rivers would give Darwin a chance to study many diverse form of life.Almost from the start of the voyage, The young man who had hated work suddenly began to work with enthusiasm, despite lack of formal training. Througout the journey to South America, he collected and examined marine life.
Amplifying earlier ideas of the geologist James Hutton,Lyell argued that processes now molding the earth`s surface Volcanic activity, the gradual uplifting of mountain ranges,erosion by wind and water had also been at work in the past. This concept is called uniformtarianism.

Darwin returned to England in 1836, after nearly five years at sea. In the years to follow his writing established him as a respected figure in natural history.All the while, his consuming interest was the "species problem" What could explain the remarkable diversity among organisms? As it turned out, field observations he had made during his voyage enabled him later to recognize two clues that pointed to the answer.

Picture of Skeletons of of Different Pigeon Breeds Preserved By Darwin Himself

First, while the Argentine coast was being mapped, Darwin repeatedly got off the boat.He made many excursions inland, where he made detailed field observations and collected various fossils.He saw for the first time many unusual species, including Armadilo.Among the fossils were remains of glyptodonts: extinct animals that looked suspiciously like living armadillos. Here were two bizarre but very similar animals, separated in time but confined to the same part of the world.If both had been created separately at the same time, then why were Armadillos lumbering about the very spot were fossil remains of others like them lay buried? would`t it make more sense to assume that one form evolved from the other?

Second, Darwin had observed local populations of the same species at many different places along the east coast of South America.It later struck him that individuals within those populations varied in such traits as size, form,coloration, and behavior.When two populations were geographically close, the differences often did not amount to much.But when populations were separated by distance, the differences are so pronounced that they might almost be judged as separate species. The phenomenon of geographic variation was pronounced in the Galapagos islands, about 1000 kilometers of  the coast of Ecuador. This tiny islands arose  long ago as volcanoes from the sea floor, hence originally had been devoid of life.Every island or island cluster housed diverse organisms, including its own species of Finch. Each Finch species had a
distinct type of beak shape, which seemed to be related to particular types of food in the local environment. Now if all those species had not changed since the moment of their creation, then a slightly different Finch must have been created for each speck of land in the Galapagos group. Would it not be simpler to assume that geographic variants had evolved from a single ancestral species of Finch?

Darwin`s Finches

 Third, after reading Essay on the principle of population by Thomas Malthus ---- A clergyman and economist.Malthus stated that "nature has scattered the seeds of life abroad with the most profuse and liberal hand has been comparatively sparing in the room and the nourishment necessary to rear them. "Thus any population tends to outgrow its resources, and its individual members must compete for what it available.

Deduction and Natural Selection:
When the Darwin reflected on his observations of the natural world, It dawned on him that the normal variation in local populations of a species could include differences in the ability to acquire resources. If there were indeed a struggle for existence, then some variant individuals might have a  competitive edge in surviving and reproducing. Nature would select certain traits and eliminate others and slowly the population could change. Thus Darwin deduce that " Natural Selection".

Among variant individuals could be a mechanism of evolution. On the basis of such reasoning.Darwin put together his "Theory of Natural Selection, which is expressed here in modern form:

1)  In any population,more offspring tend to be produced than survive to reproduce than can survive to reproductive age. Like Single Sea Star can release 2,500,000 eggs every year, but the ocean obviously do not fill with Sea Stars.

2) Members of a population vary in form and behavior. Much of the variation is heritable.

3) Some varieties of heritable traits improve chances of surviving and reproducing under prevailing conditions.

4) Because Bearers of such traits are more likely to reproduce, their offspring tend to make up more of the reproductive base for each new generation. This tendency is called Differential reproduction.

5) Natural selection is the result of differential reproduction. Some traits show up (are selected for) with increased frequency because their bearers contribute to proportionally more offspring to succeeding generations.

Waptia :animal from Cambrian Shale and VenusFlytrap
Picture of Salmon fry

Darwin took a crucial idea from the population theorist Thomas Malthus: More individuals are born than can survive and reproduce, given the limitations of food and space. Malthus wrote about human society, but Darwin applied this to all species.The overabundance of offspring, such as Salmon fry,creates competition, in which better adapted individuals succeed.Failure means death without offspring- or, for the Waptia, a peculiar animal known only from Cambrian Shale, extinction without descendant species. Insectivorous plants such as the Venus Flytrap occupy nutrient-poor soils where competition is less severe, and survive by supplementing their diet with captured insects.

Fancy Pigeons

Bull baiting Bull-Dog

Domestic Selection:
The Bulldog , shaped by many generations of Dog Breeders for bull baiting and, later for homely charm, differs much from its wolfish progenitors. If domestic breeding could yield such change, Darwin Realized, natural selection over many millions of years could do more.He argued that wild species diverge from common ancestors just as  domestic varieties do. Using his own backyard aviary, as well as information from other breeders, he analyzed differences among fancy pigeons such as the English Pouter, The Scandaroon, and the Nun.He also studied Cats , Horses, Pigs rabbits ,ducks and other Livestock. He examined and measured specimen, alive and dead. To a Friend he wrote "I have puppies of Bull -Dogs and Greyhound in salt ."

Long Necked Giraffe riddle by Darwin`s natural selection theory:

Solve of Long Necked Giraffe riddle by Darwin`s natural selection theory:

In the light of natural selection theory we can now rightly deduct that why modern days Giraffe have long Neck?

Giraffe and Ape Skeleton

Because on the early days in the Giraffe population both type of Giraffe are came into existence , but long necked Giraffe have a advantage to eat leaves from very tall trees during dry season compare with short-necked Giraffe. Long Necked Giraffe is the "Survival of Fittest" over short necked Giraffe., therefore nature select only long necked Giraffe. Therefore long necked Giraffe spread their long necked type through generation after generation. So ultimately long Necked Giraffe is the only type among the Giraffe Population

Darwin`s theory still faced a crucial test.If evolution occurs, then there should be evidence of one kind of organism changing into a different kind.The fossil record seemed to contain no transitional forms, the so called "missing links" between one major type of organism and another.Oddly enough, two years after Darwin`s book was published such a fossil did turn up and no one paid much attention to it. The fossil specimen named Archaeopteryx, had traits reminiscent of small two legged reptiles and modern birds. Like reptiles, it had teeth and a long, bony tail.Yet its entire body was covered with feathers.

Skeleton and Picture of Darwin`s Rhea
Ants Preserved in amber fossil

Anatomical Clues:
In the wild of Argentina,Darwin saw two species if large flightless bird, one of them called Darwin`s Rhea in his Honor. Why did south America harbor these similar forms, rather than Ostriches, as in Africa, or maybe Moas as in the New Zealand? such clustered patterns of what he called "Closely allied" species suggest local evolution from common ancestors. Two Primitive worker Ants Preserved in amber fossil from the cretaceous period offer another short of evidence : anatomical clues such as Wasp like antennae and a broad waist, revealing their Transitional status between ancestral Wasp and Ants.Bio geography (Which animal live where) and the fossil record are as important for modern biologists as they were for Darwin.

Whale like creature now called Dorudon.
five-fingered bone structure; a vestigial rear foot has lost several toe bones

Evolution of Fore-Limb From Early Reptile To Different Modern and Early Birds into Wings, Flippers etc.

Fossil Evidence:
At dig in Egypt a team of Paleontologists, among them the University of Michigan`s Philip Gingerich, found the nearly complete skeleton of a Whale like creature now called Dorudon. Dating back 40 million years, it had a detached pelvis near the end of its tail and useless little legs. Like the Human hand, an early Whale`s front foot retains a five-fingered bone structure; a vestigial rear foot has lost several toe bones, but its very existence testifies to the whale`s Descent from a four legged ancestor . Illuminating but spotty, the fossil record is like a film of evolution from which 999 of every 1000 frames have been lost on the cutting room floor.Still Gingerich and others have found dozens of intermediate forms- missing links that are no longer missing.

Gregor Mendel an Austrian monk (Top left) ,1952 X-Ray diffraction photo of DNA, DNA chip
fruit fly Drosophila melanogaster , Chimpanzee

The Genetic Revolution:
Gregor Mendel an Austrian monk, discovered the fundamentals of Genetics in Darwin`s time, but his ideas, published in an obscure journal, were ignored. later biologists merged evolutionary theory with genetics, though they still did`nt understand how genetic information was stored in a molecule. Rosalind Franklin`s 1952 X-Ray diffraction photo of DNA helped James Watson and Francis Crick solve the molecule`s double Helix Structure.The new field of genomics uses information technology such as the DNA chip , charting the relationships among such different species as the fruit fly Drosophila melanogaster , Chimpanzee , and ourselves. We`ve come a long way since Darwin looked for evidence in his Pigeon Coop.

Barry Kreiswirth holding the chest x-ray of a TB infected patient in his studies of Drug Resisting TB.

How Evolution Touches You:
Bacteria and viruses evolve too. Infectious agents such as Mycobacterium tuberculosis, the bacterium that causes tuberculosis, adapt quickly and acquire genetic resistance to drugs. Evolutionary theory underlies the work of medical researcher Barry Kreiswirth holding the chest x-ray of a TB infected patient in his studies of Drug Resisting TB.

Jamican twig Anole strikingly resembles the Puerto Rican twig Anole and the Hispaniolan twig Anole .
Jamican twig Anole strikingly resembles the Puerto Rican twig Anole and the Hispaniolan twig Anole .

Convergent Evolution:
Its short legs suited for clingging to narrow branches, the Jamican twig Anole strikingly resembles the Puerto Rican twig Anole and the Hispaniolan twig Anole . Yet DNA based studies by Jonathan Losos of Washington University in St. Louis, and his Colleagues, reveal a deeper reality: that such adaptations have evolved independently on the separate islands.The Jamaican Twig Anole is more closely related to other Jamaican Anoles such as the Jamaican giant Anole than to the similar twig anoles on other Islands. Specialized Anoles native to Hispaniola and Jamaica are likewise not closely related to parallel specialists on other Islands.The lesson : Although variations occur randomly, similar ecological circumstances sometimes yeild uncanny similar adaptation.

No other evidence was forthcoming in Darwin`s time. Almost 70 years would pass before solid evidence would show that his idea of evolution holds under a many different tests, on many different levels of biological organization. Ironically, even though the idea itself had at last gain respectability, it would be that long before most of the scientific community would agree with Darwin and Wallace`s remarkable insight that natural selection is the major mechanism by which  evolution occurs. In the meantime, their names would be associated mostly with the concept that life evolves.

Part Of the DNA Structure display on metal strings

Darwin`s Evolution Theory on the Light of Modern Genetic Science:

Chromosomal Aberrations



According to modern genetic science changes occur in the genetic make up of any organism due to 1) Chromosomal Aberrations 2) Gene Mutations . Most of the Time these genetic changes not helpfull for any species, but in long term these changes become helpful for evolution when nature selects only favourable changes for survival of any particular species within a particular condition and places. Then those favourable Changes selected by the Nature, propagated generation after generation and formed new type of changed Organism. For Example Sickle-Cell anaemia.

sickle-cell anaemia (or anemia, SCA)

Sickle-cell disease (SCD), or sickle-cell anaemia (or anemia, SCA) or drepanocytosis, is an autosomal recessive genetic blood disorder with over dominance, characterized by red blood cells that assume an abnormal, rigid, sickle shape. Sickling decreases the cells' flexibility and results in a risk of various complications. The sickling occurs because of a mutation in the hemoglobin gene. Life expectancy is shortened. In 1994, in the US, the average life expectancy of persons with this condition was estimated to be 42 years in males and 48 years in females,but today, thanks to better management of the disease, patients can live into their 50s or beyond. In the UK, the current life expectancy is estimated to be 53–60 years of age.

Sickle-cell disease, usually presenting in childhood, occurs more commonly in people (or their descendants) from parts of tropical and sub-tropical regions where malaria is or was common. One-third of all indigenous inhabitants of Sub-Saharan Africa carry the gene,because in areas where malaria is common, there is a fitness benefit in carrying only a single sickle-cell gene (sickle cell trait). Those with only one of the two alleles of the sickle-cell disease, while not totally resistant, are more tolerant to the infection and thus show less severe symptoms when infected.Therefore carrier of Sickle cell   have more advantage from Malaria than the normal blood cell.

Evolution of Horse from early Smaller Species by comparing their limbs anatomy

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