In the middle 1800s Charles Darwin published a book called On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. This book, more commonly known as Origin of Species, presents the theory that small positive changes to an organism over time will result in a new species of animals being created. That this positive adaptation would give the animal an advantage in their environment, causing it to thrive and eventually replace the old species that lacks the new character trait. This theory is also described as “descent with modification” said Briana Pobiner, an anthropologist from the Smithsonian Institution National Museum of Natural History in Washington, D.C. Dr, Pobiner specializes in the study of human origins.
The “engine” that drives this theory is called natural selection. To give you an idea of how this works, say we have a medium haired dog that lives in a moderate climate. This dog migrates north and has several litters of puppies. Some of these puppies will be able to grow longer coats of fur, giving them an advantage over their siblings. This would allow them to be more successful at surviving than their short haired siblings. In time the new long haired dogs would replace the medium haired ones. As these new long haired dogs mated this characteristic would increase.
Sometimes Darwin’s theory is called the survival of the fittest, but it’s not really accurate. The biggest and strongest animal is not alway the one that will endure through time. More critical to survival is how many offspring can the animal produce and how many natural predators does a species have? Is food plentiful and can there environment support them generation after generation.
Through natural selection a species can change, it may be by color or size. These types of changes can be seen in the horse population. From one common descent came donkeys, zebras and all other types of horses. They all originated from a common horse ancestor. This is known as microevolution and we see it throughout our environment. Microevolution can be the result of mutation, migration, genetic drift or natural selection.
Darwinian theory presents the idea that given enough time, these small changes can eventually result in an entirely new and different species. That a reptile over long periods of time, can become a bird or a land based animal, that is adept in the water, could become a whale. This process could happen something like this. Say our land based animal finds a food source in the ocean and decides to live out there. It survives and has offspring out in the ocean. Through multiple generation a random modification happens in which one of the offspring has an advantage. Perhaps the nostrils are formed higher up the head making it easier to breath in the water. This genetic trait would be passed onto it’s progeny. Over millions of years other random mutations would give the animal advantages, like shorter front arms that would eventually become flippers. This animal would become a new and completely different species. This is known as macroevolution or darwinian evolution.
When Darwin proposed his theory in the mid-1800s there was no understanding of micro microbiology, DNA, RNA ribosomes or even a rudimentary understanding of the vast complexity of a cell. Today we have a better understanding of how these genes pass along adaptation (mutations) from one generation to the next. By incorporating genetics into the darwinian theory a new field of study was formed called modern evolutionary synthesis.
Microbiology now understands that evolutionary changes are the result of changes happening within the genes of the animal. These changes happen at the DNA level and are called mutations. Mutations can be caused by DNA that has been improperly repaired or by chemicals or radiation being introduced into the cell. Every time a cell divides mutations are created in the new cells. This is known as genetic entropy, it’s the reason everything dies. Most genetic mutations are harmful to the organism, but darwinian theory believes that every once in awhile a random mutation is beneficial to the animal. That this new trait is passed on to the next generation.
One of the problems with evolution is the origin of life. That through random events, a simple cell came into existence and could reproduce. Darwin’s theory of evolution believes that all life originated from this first cell.
All living cells require amino acids, these are small protein molecules. There are 22 different kinds of proteinogenic (protein building) amino acids used in building protein molecules for life. The order that these amino acids are linked together determine the type of protein. In order to have the simplest form of life you need to have 100 different kinds of protein molecules. Certain protein molecules that are essential to life don’t occur naturally in nature.
If we look at how the protein molecules are formed In a living cells we see nano-machines making them. A machine called a RNA polymerase (enzime) runs down the DNA strand and it creates a strand of RNA. The RNA strand is fed into another machine called a ribosome. This machine reads the information on the RNA strand and links the correct amino acids together, in the right order, to create a protein strand called a polypeptide. Chaperone molecules protect and transport the polypeptide strand to another machine called a chaperonin that helps bend the new protein molecule into its final shape. The shape of the protein molecule determines what the protein molecule can be used for. Without these organic machines, making these kinds of proteins is very difficult. Improperly folded protein molecules called amyloid plaques are clumps of proteins that can cause disease. They are responsible for Huntington’s, cystic fibrosis, Mad Cow and Alzheimer’s disease. These mis-formed protein molecules are hard for the cell to get rid of and the chaperonin can actually help refold some these molecules and aid in their removal.
Another challenge is getting the amino acids to bond to one another. To get amino acids to link, you need to put them in a proper solution. Water, if used for the solution, will dissolve the bonds and the protein molecule will to change back into amino acids.
Another challenge is the corality problem. The amino acids in proteins molecules and the sugar molecules in DNA, have to be mirror forms. All of the amino acids have to be left handed and all the sugars in the DNA strand have to be right-handed. When amino acids and sugars are made in a lab the result is both left and right handed molecules of both types are made. In order for them to connect to one another properly, you would need to separate the left and right molecules. A random process would not have the know-how of how to do that.
DNA is the assembly instructions for making everything in you body and it’s a lot like a software program in a computer. A DNA strand is subdivided into various areas call genes. A gene is the complete instructions to make a specific part of your body. For instance, if your body needed a certain protein molecule, it would access the part of your DNA to “learn” how to make that molecule. That area would be classified as a gene. Even simple forms of life require a lot of information. The simplest organism, mycoplasma genitalium has over 650 kilobytes of information in its DNA.
For chemical reactions to occur in a cell you need to have enzymes (the catalyst). An enzyme can speed up a reaction in a cell by well over a million times. Without them a chemical reaction that takes about 100th of a second would take well over a thousand years! Enzymes are necessary because protein and sugar molecules would decompose before the reaction took place.
RNA is used in some reactions as a catalysts but most biological reactions are catalyzed by proteins. In the absence of protein based enzymes, most biochemical reactions would be to slow. Cells contain thousands of different enzymes and they are specific to a purpose. They are specialized for a certain chemical reaction to place in a cell. The simplest organism is the mycoplasma genitalium and it needs over 350 different types of enzymes to function.
You need to have enzymes in order to read DNA, but to make the enzymes you have to get the information off of the DNA and then you need the molecular machinery to make the enzyme. It appears all this has to happen simultaneously and this is why many biologists find the problem insurmountable.
Cells run on ATP, it’s a molecule that stores a lot of energy. Just about everything that we do requires it. In order to create ATP there’s an amazing little machine called a ATP synthase motor. It runs on a tiny electric motor that creates rotational spin by using protons. It takes ADP molecules and attaches a phosphate molecule to it creating an ATP molecule. ATP molecules are not made through a natural or random process. So the question is, if a cell needs a lot of ATP in order to function, where did the cell get the ATP before nano machinery was created to produce it?
RNA world is a theory that was presented by Carl Woese back in 1967. It postulated that RNA can act as a catalyst, removing the need for protein based enzymes. Two scientists, Thomas Cech and Sidney Altman verified the catalyst effect of RNA and received the Nobel Prize for there work in 1989. RNA world also suggests that RNA can be self producing.
From this work evolutionists theorized that early life could have stored genetic information on RNA and not DNA. That the ribozymes (catalyst) that are present in the RNA could have acted as the catalyst needed for early life. To support this claim scientists have looked to the ribosome. THe ribosome is a molecular machine that takes RNA and makes polypeptides (chains of amino acids). The ribosome attaches the amino acids together by using ribozymes.
To make the large and complicated protein molecules required for life, you have to have a functioning ribosome. RNA world theorizes that in early life a ribosome is made solely of RNA. All ribosome’s that we know of today are made of both protein and RNA molecules with no evidence of an RNA only ribosome.
Problems with the Theory
- RNA is not very stable, the building blocks for RNA are ribose (last about 44 years frozen), uracil (will last 12 years), adenine, guanine (both last about a year) and cytosine (19 days). A very short time on the evolutionary scale.
- When making RNA you have the same problems as DNA. The arrangement of the molecules is very complex. Even in a lab making these molecules is difficult.
- There is still the corality problem that was discussed above.
- RNA is very fragile, DNA is more robust and it breaks in cells. Everyday there are about about one million DNA brakes, however, our cells have the ability to repair these breaks. Again we see a nano-machine repairing the broken DNA strand.
- Accuracy in replication is essential. If an early RNA strands replicated with an accuracy of less than 3.3 percent the errors would ruin the strand. In DNA there are systems in place that protect the DNA code, causing only 1 mistake per billion.