Evolution From A Molecular Perspective Essay Research

Evolution From A Molecular Perspective Essay, Research Paper

Evolution From A Molecular Perspective

Introduction: Why globular evolution?

Evolution has been a heavily debated issue since Charles Darwin first

documented the theory in 1859. However, until just recently, adaptation at a

molecular level has been overlooked except by the scientific world. Now with

the help of modern technology, the protein sequences of nearly every known

living thing have either been established or are in the process of establishment,

and are widely accessible via the internet. With the knowledge of these

sequences, one can actually look at several organisms genetic codes and point

out the similarities. Entire genomes of creatures have been sequenced, and the

human genome project is well underway and ahead of schedule. With this new

knowledge comes worries, for humans, however. What if the information stored in

our genes was available to the public? Would insurance companies and employers

base their selections on these traits? Also, with the total knowledge of every

sequence of every amino acid chain in a person’s genome, couldn’t a laboratory

perceivably reconstruct an exact copy of, or clone, that person? These are all

issues that will have to be dealt with in the near future, but for now we need

only concern ourselves with the objective observation of these proteins in our

attempt to explain our ever mysterious origin. As humans, we are the first

creatures to question exactly where we came from and how we got here. Some

cling to religious creationism as a means, while others embrace the evolutionary

theory. As of now, and possibly forever, neither can be proven to be absolute

truth with hard facts, and both have their opposing arguments. The point of

this paper being composed is not to attempt to abolish the creationist view, a

feat that at this point seems impossible, but merely to educate those seeking to

unravel the mystery of our forthcoming by pointing out facts that exist in the

modern world and that can be quite easily and independently researched. It is

conceivable that the two ideas, creationism and evolutionism, can exist

symbiotica lly due to the fact that both views have very good points.

Hemoglobin: Comparisons between species

Of all the proteins in living things, hemoglobin is “the second most

interesting substance in the world,” as American biochemist L. J. Henderson once

stated (Hemoglobin, 4). However bold this statement seems, it must be realized

that hemoglobin is, at least in the scientific world, by far the most studied

and most discussed substance in the human body, as well as in other living

organisms. Hemoglobin is the carrier in blood that transports oxygen to our

tissues and carbon dioxide out of our body, changing colors as it does so.

Hence, hemoglobin has long been termed the pigment of our blood. Hemoglobin was

one of the first proteins to be purified to the point where its molecular weight

and amino acid composition could be accurately measured. This finding was very

important in that it eventually lead to the understanding that a protein is a

definite compound and not a colloidal mixture of polymers. Each molecule was

built from exactly the same amino acid subunits connected in the same order

alonga chain, and had exactly the same weight. Most organisms have their own

unique, individual chain of proteins to make up their hemoglobin, but all

organisms share certain similarities, so striking that they are unable to be

ignored. Let’s take, for example, the first twenty-five amino acids in the

alpha hemoglobin chains of 7 different animals: a human man, rhesus monkey, cow,

platypus, chicken, carp (bony fish), and shark (cartilaginous fish) (See Table

1.1.) As is shown, the variations increase the further apart the organisms are

on the proposed evolutionary scale. A human man differs from a rhesus monkey

only twice in the first twenty-five amino acids of their alpha hemoglobin chains,

whereas a man and a cow differ in three areas. This is the product of many

thousands of years of natural fine tuning, if you will, through the slow but

precise processes of natural selection and adaptation. The fact of natural

selection shows us that while most genetic mutations usually prove fatal, a slim

few are ac tually beneficial, and assist the mutant in living and procreating

offspring. This assistance helps the mutant-gene’s frequency grow in the gene

pool and remain there since all progeny possessing this certain trait are going

to have an advantage over the other organisms lacking this quality. This is the

basis for evolution. The higher a certain species is on the evolutionary scale,

the more advanced that organism is due to a slight change in the amino acid

sequences of certain genes. An example would be that of the human man, the

rhesus monkey, and the cow. There is a smaller difference in the amino acid

sequences between a man and a monkey than between a man and a cow, and,

respectively, a monkey is more advanced than a cow, genetically (monkeys and

humans have far advanced apposable thumbs.) Also, where the amino acids have

been conserved between all the studied organisms, such as in columns 27, 31, and

39, indicates that in order for the species to survive, that certain amino acid

must be there. it is changed in any way, the organism can not survive. There

are thirty-four conserved positions in the first 141 amino acids in the seven

studied organisms. After just these few demonstrations, how could anyone doubt

the theory of evolution? This question leads me into a short interlude where I

will discuss the arguments on both sides, and show just how endless this debate

could be.

Evolution -vs- Creation: Which Is Truth?

When evolution is mentioned to many people, the first thing that enters

their mind is the completely incorrect thought that man evolved from monkeys.

Man did not, in fact, evolve from monkeys, this is a known and agreed upon fact.

The only connection between modern day men and modern day chimpanzees, for

example, is the fact that they must have shared a common ancestor. The “common

ancestor” theory, as I have chosen to name it, states that all life living, or

ever to have lived on this planet can be traced back to a single, common

ancestor. At some point in time, between 3.5 and 4.1 billion years ago, a

certain grouping of chemicals came together at just the right time and life

began. From this single life-form, the slow process of natural selection began.

First came the proteinoid microsphere, the first organisms on the planet to

carry on all life functions. Eventually, then, came viruses, parasites,

saprophytes, holotrophs, chemosynthesizers, and photosynthesizers, all mutants

of the very first cell. Some have tried to use thermodynamics to disprove

evolution, especially the second law. The second law of thermodynamics states

that “all energy transfers or transformations make the universe more

disordered.” These speculatives claim that since man is more advanced than any

other creature, we are more ordered. This is wrong. Man is more advanced due

to the mutations in his genes. Compared to the very first life-form’s genes, a

human man’s amino acid sequences are very dissimilar, or more disordered. Also,

the first law of thermodynamics can be used for either argument. The first law

of thermodynamics states that energy cannot be created or destroyed–in other

words it has always been here. Using this law, the matter in the universe can

either be thought of as always being here, or that the creator, with his

infinite power, simply transformed the energy that he possessed into the matter

of the universe. Both sides have an arguable point that agrees with the laws of

thermodynamics. Anot her arguable point that is worthy of mention is the

discrepancies in the fossil record. The Earth’s crust, and all the fossils

contained therein, can also be utilized as arguments for both sides. The “Pre-

Cambrian Void” (Creation-Evolution: The Controversy, 362) shows very little sign

of fossilization. Then, suddenly, massive amounts of fossilization can be found

during the Cambrian times, pointing to some sort of catastrophe, like a flood.

The Bible mentions a flood sent by God to destroy every living thing on Earth.

The fact that a flood could have happened, in that sense, strengthens the

creationists’ views. The evolutionist theory can use these facts in two ways.

One, when the selection pressure on a species is constant for a long time, a

species could become so specialized that any slight change in their environment

could lead to extinction, this is called a climax group. Around the time that

the large amounts of fossilization was occurring, the Earth had cooled down

enough to allow the immense ly dense atmosphere to condense, thus causing many

years of rain. Would not this rain cause almost any climax group’s entire

population to become extinct? Also, before the rains came, the great majority

of the organisms inhabiting the Earth were land creatures. Once the rains came,

the Earth was covered in water, killing thousands of populations, and

effectively burying them in the water. The water preserved their parts for

fossilization. These have been just a few double sided arguments demonstrating

that either side can turn any facts around to fit their own hypothesis.

Leghemoglobin, Protein Relations Between Species, and the Evolution of the

Globin Family

Like animals, plants also carry a sort of hemoglobin, leghemoglobin.

Leghemoglobin is a globin which is less evolved than that of hemoglobin or

myoglobin. The whole globin family, itself, has undergone much evolution and

mutation. At one time, animals had no globin at all. As life evolved, a

single-chain oxygen-binding substance formed–we will call this the basic globin.

Then life branched into two parts: animals carrying the basic globin, such as

annelid worms, insects, and mollusks, and creatures (manly plants) carrying

leghemoglobin, a mutation of the basic globin. The animal kingdom’s globin

eventually split into myoglobin (Mb) and hemoglobin (Hb). Since then, myoglobin

has basically stayed the same in many organisms (See Table 1.3.) Hemoglobin, on

the other hand, has undergone some major mutations. After the basic globin

bifurcated into Mb and Hb, Hb split into alpha (a) and beta (b) chains. The a-

chain eventually split into two parts, and has remained this way up to present

times. The b-cha in split into many more parts. Everything that has been said

up until now about the evolution of the globins from a common single-chained

oxygen-binding ancestor has been summarized in Table 2. If one would compare

sequences of globin between species, one would notice that the less amino acids

that are different the more closely related two species are. If we used this

theory on the vertebrates that were studied it would give us a “schematic family

tree of globin containing vertebrates” (Hemoglobin, 78) (See Table 3). This

same tree is obtained by comparing sequences of myoglobin, or the a or b chains

of hemoglobin. This tree tells us that all organisms alive today are just as

evolved as any other living organism. Different species evolve in different

ways, that is the basis of evolution. Man is just as evolved as a chimpanzee,

or a carp, or a rose bush. Different organisms simply evolved differently.

Another excellent way of showing the relationships between organisms is the mean

amino acid differenc es. The more amino acids that are different between two

species, the further apart they are genetically. For instance, of the entire b-

chain of human and rhesus monkey hemoglobin, there are, on the average, eight

places where the amino acids are different. However, when comparing b-chains of

man and platypus, there are thirty four average differences. A chart and a

graph can help us better understand these points (See Table 4.) The amino acids

that have changed are a result of mutated DNA that has proven beneficial to the

carrier mutant. This process, as stated before, is the basis of evolution.

Speaking solely of hemoglobin, the variances between species can be

shown through greater or less affinity for oxygen. “H. F. Bunn has shown that

mammalian hemoglobin can be divided broadly into two groups: the great majority

have intrinsically high oxygen affinity, which is lowered in the red cell by

DPG,” (D-2,3-biphosphoglycerate) “while those of ruminants and cats (Cervidae,

Bovidae, Felidae) and of one primate, the lemur, have an intrinsically low

oxygen affinity that is little, or not at all, lowered by DPG (”Species

Adaptation in a Protein Molecule”, 16). DPG is one of the ligands that “reduces

the oxygen affinity of hemoglobin in a physiologically advantageous manner by

combining preferentially with the T structure.” (”Species Adaptation in a

Protein Molecule”, 3) For instance, the mole (Talpa europaea) lives in its

burrows under conditions lacking a rich oxygen supply. This creatures

hemoglobin has adapted to having a high oxygen affinity, a high concentration

per unit volume of blood, and a lo w body temperature. This high affinity is

due to the mole’s hemoglobin’s low affinity for DPG. So as you can see, DPG

asks as a type of buffer. The more DPG the creature’s hemoglobin can hold, the

less space it has for oxygen. Since the environment has low amounts of oxygen,

the blood needs to hold as much oxygen as possible, so the mole has adapted.

Which Came First?

One final point that should be mentioned is the question of which change

came first. Did a mutation occur that adapted a species to a new environment

take place before the species occupied that environment, or did the genetic

change occur after the environment changed in order to assist the creature with

living in its new surroundings? “W. Bodmer suggested that once a large change

in chemical affinities produced by one mutation had enabled a species to occupy

a new environment, its effect might have been refined by later adaptive

mutations, each contributing minor shifts, over a long period of time.”

(”Species Adaptation in a Protein Molecule”, 22.) For example, did a llama’s

hemoglobin adapt to a higher grazing altitude by increasing the oxygen affinity,

or did the oxygen affinity increase and the llama then realize that it could

graze higher than some other animals. This could show the “punctuated

equilibria” (Biology, 296) in the evolution of a species.

What Does It All Mean?

After seeing all of these demonstrations of adaptation at a molecular

level, you may ask what it adds to the betterment of the world. The truth is,

merely knowledge. It is doubtful that the evolution-creation controversy will

ever be settled, but without interest, research, and work by people in all

corners of the debate, be it theological, or scientific, the answer will never

be discovered. It is quite possible that neither hypothesis is correct–perhaps

the truth lies in a combination of the two, or something completely different.

I believe that the truth, at least a partial truth, can be found somewhere at

the molecular level. If the genes, and amino acid sequences are examined, I

believe that the actual evolutionary time table can be reconstructed. The human

species, however, must be the last “stem” on this branch of the evolutionary

tree, due to our personal views of mutations. We all see mutations as negative,

when some may actually be positive. If a child is born with twelve fingers

instead of ten, two are surgically removed, and the child becomes less

attractive to the opposite sex, and may not get his mutated genes back into the

gene pool. This process has almost always worked in the opposite way in every

species up until now–the mutant with the beneficial, but different, genotype

and (perhaps) phenotype has had an advantage that makes him more attractive to

the opposite sex, and his genes are passed on to his offspring. One of the only

mutations that could, and has, gone unnoticed is the expansion of the control of

the mind. Over the hundreds of years of human existence, especially in the past

few decades, the knowledge of the modern man has expanded dramatically, and now,

with the ease of the internet, anyone can learn about anything imaginable.

People are tired of mind-numbing thoughtless hours spent in front of the

television, and are now expanding their minds in their free time. I can only

hope that this paper has inspired some thought about the subject, and has

brought us a small step closer to the conclusion of the debate.

Works Utilized

Dickerson, Richard E. and Geis, Irving. Hemoglobin: Structure, Function, and


California: The Benjamin/Cummings Publishing Company Inc., 1983. Perutz,

Max. “Species Adaptation in a Protein Molecule”, Molecular Biology and

Evolution Chicago: University of Chicago, 1983 Mammrack, Mark.

Biology 112 Lecture Notes. Ohio: Wright State, 1996 Wysong, Randy. The

Creation-Evolution Controversy. Michigan: Inquiry Press, 1978 Lasker, Gabriel.

Human Evolution. New York: Holt, Rinehart, and Winston, Inc., 1963 Campbell,

Neil. Biology Second Edition. California: The Benjamin/Cummings Publishing

Company Inc., 1990 Solomon, Eldra; Berg, Linda; Martin, Diana; Villee,

Claude. Biology Fourth Edition. New York: Saunders College Publishing,

1996 Genbank. National Center for Biotechnology Information, 1996

Available www: http://www2.ncbi.nlm.nih.gov/cgi-bin/genbank

–Tables!– (tables 2-4 were scanned in from the

Hemoglobin book in the Bibliography GET IT!)

Table 1.1 Sequence comparisons of globin (information gathered from Hemoglobin

and from “Genbank”)

1 25

50 67










1. Human Man 2. Rhesus Monkey 3. Cow 4. Platypus

5. Chicken 6. Carp 7. Shark

Table 1.2 Sequence comparisons of globin (information gathered from Hemoglobin

and from “Genbank”)

68 75

100 125












1. Human Man 2. Rhesus Monkey 3. Cow 4. Platypus

5. Chicken 6. Carp 7. Shark

Table 1.3 Sequence comparisons of globin (information gathered from Hemoglobin

and from “Genbank”)

125 50

75 80











1. Human Man 2. Cow 3. Sperm Whale 4. Platypus 5.

Chicken 6. Shark

Table 1.3 Sequence comparisons of globin (information gathered from Hemoglobin

and from “Genbank”)

125 50

75 80

MYOGLOBIN (part two)









1. Human Man 2. Cow 3. Sperm Whale 4. Platypus 5.

Chicken 6. Shark


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