I’ve heard it a hundred times, our DNA is 99% similar with Chimpanzee DNA. The statistic’s purpose is obvious; if our DNA is so similar we must be related and have a common ancestor. Clearly we share evolutionary ties to the chimpanzee. This was further solidified in my mind while taking a course in Human Genetics, in which I learned exactly how this statistic came about. In this article I will present the evolutionary side of this subject as I was taught in my Human Genetics course, then I will present an alternate view of these similarities. So first, let’s begin with how these similarities were first discovered.
In the 1970’s a study of the human genome and chimpanzee genome yielded a repeated estimate that our DNA was 98.7% similar. This was discovered by a process called DNA-hybridization. The hybridization process involves taking DNA from two different species and heating them up so they that they both unwind. Once they unwind, complementary pieces bond together forming hybrid molecules. The higher the temperature that is required in order to separate the hybrid DNA means the more the DNA between the two species were similar, because more bonds would need to be broken. Two species that had very dissimilar DNA would be unable to form as many hybrid bonds and therefore could be unwound at a much lower temperature. This is how the 98.7% statistic is reached.
Another way scientists can measure the similarity and differences between human and chimpanzee DNA is by tracking “indels,” which stands for insertions and deletions. The human genome has additional sequences (insertions), and lacks other sequences (deletions) when compared to the chimpanzee genome. By observing the sequences we share, we are 96.6% similar to the chimpanzee, and via the sequences we don’t share we are 94% similar to the chimpanzee.
However, these statistics are reached by tracking single genes. Single genes can have the ability to cause major distinctions. For example, the ability to speak, opposable thumbs, large frontal lobe of the brain can all be determined by one gene. The speaking gene known as FOXP2 OMIM 605317 is sometimes found missing in people and they have no ability to speak. This same gene is found in Chimpanzees, though the gene is slightly different so the chimpanzees cannot speak. In other words, the chimpanzee may look and behave very dissimilar to humans, but these are merely single gene differences. The FOX P2 protein created by this gene contains 700 amino acids, of which 698 of the amino acids are identical between human and chimpanzees. That’s a 99.7% similarity!
When a cell is preparing to split during mitosis the DNA inside the cell coils up tightly to form chromosomes. Our chromosomes can be compared to chimpanzee chromosomes to observe similarities. This was the initial way to observe similarities (outside of fossil comparison) prior to the advent of gene and genome sequencing. Comparing banding patterns on human chromosomes, we are 99+% similar to Chimpanzees, Gorillas and Orangutans, 95% similar to African green monkeys, 35% similar to cats, and 7% similar to mice.
There is also another way to observe similarities in chromosomes, which is done by using FISH analysis. The FISH method involves using DNA probes that are complimentary to particular DNA sequences. These DNA probes will naturally bond to the DNA they’re similar with. But the probes are also attached to a fluorescent molecule, so that once a DNA probe attaches itself it can be seen under proper lighting illuminated. Using the FISH method, similarities in Chromosomes are more precisely found, and between human and chimpanzee DNA, many similarities are in fact found.
Different organisms often use the same or similar proteins. The only difference between the proteins is usually a single different amino acid in the chain. The similarity in proteins and their amino acid composition is often used by geneticists to gauge similarities between different animals. Geneticists recognize that 99% of the proteins used by chimpanzees have identical amino acids to that of human proteins. The most popular being the cytochrome c and homeobox proteins. Taking cytochrome c for example, of the 104 amino acids required for cytochrome c, 20 are identical in all eukaryotic cells. Then as you go from animal to animal, you find more and more amino acid commonality. Compared to humans; yeast shares all but 42 amino acids, fruit flies share all but 24 of their amino acids, a bullfrog shares all but 20 amino acids, a cow shares all but 10 amino acids, a rabbit all but 9 amino acids, but a chimpanzee has all the same amino acids we do used to produce a cytochrome c protein. Homeobox genes are also noted for having commonalities with chimpanzees as they can be swapped from a human genome to a chimpanzee or other animals and the gene still functions though there are often bizarre mutations that occur. These are the most widely known evidences of proteins proving similarities between humans and chimpanzees.
So, when we compile the evidence we see that humans have DNA incredibly similar to the chimpanzee, especially when comparing chromosomes and proteins. That seems pretty concrete right? How could anyone question our relation to monkeys in knowing what was covered here?
An opposing view
When counter arguing the belief that man and chimp share a common ancestor, it’s not that the evidence biologists and geneticists refer to is incorrect, it is that their interpretation of the evidence may be off. They say, “look at the similarities, we’re related!” But someone else could look at all this same evidence and come to quite a different conclusion. The Bible says God created all life. If God created all life, then it is entirely possible that He used similar design and construction in similar animals. Think of it like a car manufacturer such as Ford. The Ford focus, mustang, explorer and expedition all have similar parts because they came from the same automobile manufacturer. But the explorer has more parts in common with the expedition than compared to the mustang and focus. But this is just because they are both SUVs, while the other is a sports car and a compact. In the same way similarities found among humans and chimpanzees could just as easily be explained as similar design from the same Designer.
Humans live in the same world as all other creatures, meaning our environment is the same. Since we all live on the same planet and share the same environment it is only natural that we would discover similarities in our anatomy because we all have similar needs to live on our planet. Animals that have more similar needs would of course have more shared proteins and DNA to carry out those needs. So the similarities between human and chimpanzee DNA being greater than similarities between humans and let’s say a jellyfish, should not be a surprise. Our needs are more similar to that of a chimpanzee than that of a jellyfish.
Even so, the claimed similarities mentioned earlier aren’t exactly all what they’re cracked up to be. So let’s first address the DNA similarities. In order to know the exact ratio of similarities between humans and chimps we’d need to have an even understanding of each genome. This is not the case though. The human genome has been intensely studied and mapped, but the chimpanzee genome has not nearly been studied to the same degree. Meaning we know much more about the human genome than we do about the chimp’s. Without knowing the chimp’s as well as we know the human’s, how can we make an accurate conclusion about how similar they are? Furthermore, DNA comparison between human and chimp DNA is based on observing one gene at a time, not the entire genome. So out of three billion base pairs of DNA found in both our genomes, we study a handful of genes and determine we’re closely related. Not very concrete…
Even if we completely mapped the chimpanzee genome and compared it to the human genome as a whole and discovered that we are in fact over 90% similar, that still doesn’t mean much when you consider the complexity of our DNA. For example, if there was only a 1.23% difference of a single base pair in our DNA, that would lead to over 35 million differences altogether. Compared to a human, the chimp is missing anywhere from 40-45 million base pairs of DNA. When insertions and deletions are considered, that 4% difference mentioned earlier equals 125 million different base pairs that we do not have in common with chimps. To put that in perspective; the average 8.5 x 11 inch piece of paper can hold about 4,000 letters. It would take more than 10,000 pages to record the base pair differences that humans have and chimps do not share. Biologist and urologist Dr. Barney Maddox, “Now the genetic difference between the human and his nearest relative, the chimpanzee, is at least 1.6%. That doesn’t sound like much, but calculated out, that is a gap of at least 48,000,000 nucleotides, and a change of only 3 nucleotides is fatal to an animal; there is no possibility of change.”
The problem with believing we share a common ancestor with a chimp can also be an issue of time. It is one thing to have millions of different base pairs separating chimps and humans, but if we both came from a common ancestor, that means our differences would have been caused by mutations in our genetic material after we split away from our ancestors. The problem: Per evolutionary models humans and chimps split off about 300,000 generations ago. In order to account for the vast amount of genetic differences between us, we would have to have had experienced about 133 genetic mutations in each generation. That many mutations in such a short amount of time absurd, and is commonly known as Haldane’s Dilemma.
There are many other differences that separate humans and chimps. Telomeres at the end of each chromosome help the body control how often chromosomes can be duplicated during replication of a cell. Chimps and other apes have about 23,000 base pairs of DNA at their telomeres, while humans have about 10,000. When it comes to chromosomes the differences continue on. Though many chromosomes are like that of a chimp, the human’s 4, 9 and 12 chromosomes are very different. The Y chromosomes are also very different between humans and chimps. Humans have 23 chromosomes, chimpanzees have 24. In examining gene families, chimps have 86 genes that humans lack, and humans have 689 genes that chimps lack. As you can see the differences aren’t as small as you’re lead to believe. Percentages may make the differences seem small, but when you consider the enormous complexity of our genetic material, those small percentages make a very big difference!
Remember that FOXP2 gene and protein mentioned before with the 99.7% similarity in amino acids that enables us to speak? Well the two different amino acids are in two different places along the amino acid chain which any geneticist will tell you that even alterations that small can create major changes to the way a protein functions. Many genetic defects found in animals are in fact the result of one misplaced amino acid, which can cause an entire protein to lose function. Like a car which has hundreds of parts all working together, take away one, like a drive shaft or one of the four wheels and now you have a car that can’t be driven. Take away the computer’s extension cord to the outlet and it can’t even turn on. In the same way a protein can be rendered completely useless by one misplaced amino acid even if 99.9% of all the other ones are in place. Case in point; humans and chimps both have the FOXP2 gene, but we can talk, and they cannot.
“FOXP2 demonstrates how a difference in one amino acid can yield a protein that is regulated differently or has altered functions. Therefore, we should not be too quick to trivialize even very small differences in gene sequences.” –Dr. David A. Dewitt, biochemist and neuroscientist.
As said before chromosome banding comparison is also another method by which evolutionists compare animal relatedness. The problem with comparing the chromosome banding of different animals is that a chromosome may have the same band as another animal, but that band can contain different genes altogether. This renders band comparison imprecise. Yet many refer to this to prove animal relatedness.
If we use evolutionist’s method of comparing genetic similarities to show common ancestry we may be excited when we focus on similarities between humans and primates. But you’ll be disappointed when you compare humans to other forms of life. For example, human DNA is 50% similar to the DNA of a banana. What does that say about our ancestry? Humans share the same mutated vitamin C pseudo gene with that of guinea pigs. But per the evolution model we’re not supposed to be related to the guinea pig. When comparing the human genome to that of a pufferfish, its genome is like ours, just missing repeats and introns. As biologist and evolutionist Ricki Lewis PhD states, “It is odd to think that the protein encoding portion of our genome is nearly the same as that of a fish.” Humans share the same hemogoblins found in many plants, does that makes us related to plants? As you can see, we can find genetic comparisons to all kinds of animals, in fact, more than half of our DNA is similar to most animals. So similarities in genetics aren’t as earth shattering as they’re made out to be, but are instead a built up hype. The line is drawn between Creationists and Evolutionists in that creationists say the similarities are what we’d find if we were all created by the same Creator, where as the Evolutionists say it would be what we’d find if we all evolved from the same original organism. The problem for evolutionists is that these similarities jump around from animal to animal regardless of where they stand on the evolutionary tree.
For example: In 1996 an analysis of 88 proteins grouped rabbits with primates and not rodents. In 1998 a study of 13 genes in 14 species of animals linked sea urchins with chordates. A 1998 analysis of 12 proteins places cows closer to whales in relation than horses. Another more recent study of single chain antigen receptor proteins finds sharks in close relation to camels. Bats and dolphin both have a sonar system that is almost identical at a molecular level. These odd commonalities cannot be explained via the evolutionary tree of ancestry. But from a creationist stand point they can be explained via a common Creator.
As Dr. Dewitt concludes, “The similarity between human and chimpanzee DNA really lies in the eye of the beholder. If you look for similarities, you can find them. But if you look for differences, you can find those as well. There are significant differences between the human and chimpanzee genome that are not easily accounted for in an evolutionary scenario. Creationists expect both similarities and differences, and that is exactly what we find.”
 Ricki Lewis, Human Genetics; Concepts and Applications, Eighth Edition, (New York:NY McGraw-Hill, 2008) Pg 310.
 Wolfgand Enard, “Molecular Evolution of FOXP2, A Gene Involved with Speech and Language,” Nature 418 (2002): 869-872.
 Ricki Lewis, Human Genetics; Concepts and Applications, Eighth Edition, (New York:NY McGraw-Hill, 2008) Pg 313.
 Ibid, Pg 314.
 Dr. David A. Dewitt, The New Answers Book 3, What about the Similarity Between Human and Chimp DNA? (GreenForest:AR Master Books 2010) Pg. 101.
 Ibid, Pg. 102.
 Walter J. ReMine, “Cost Theory and the Cost of Substitution- A Clarification,” TJ 19 no. 1 (2005).
 S. Kakuo, K. Asaoka, and T. Ide, “Human Is a Unique Species Among Primates in Terms of Telomere Length,” Biochemistry, Biophysics, Res. Commun. 263 (1999): 308-314.
 Ann Gibbons, “Which of Our Genes Makes Us Human?” Science 281 (1998): 1432-1434.
 Dr. David A. Dewitt, The New Answers Book 3, What about the Similarity Between Human and Chimp DNA? (GreenForest:AR Master Books 2010) Pg. 105.
 Ricki Lewis, Human Genetics; Concepts and Applications, Eighth Edition, (New York:NY McGraw-Hill, 2008) Pg 314.
 Y. Inai, Y. Ohta, and M. Nishikimi, “The Whole Structure of the Human Nonfunctional L-Gulono-Gamma-Lactone Oxidase Gene – The Gene Responsible for Scurvy – and the Evolution of Receptive Sequences Theron,” Journal of Nutritional Science Vitimol 49 (2003): 315-319.
 Ricki Lewis, Human Genetics; Concepts and Applications, Eighth Edition, (New York:NY McGraw-Hill, 2008) Pg 311.
 Dr. David A. Dewitt, The New Answers Book 3, What about the Similarity Between Human and Chimp DNA? (GreenForest:AR Master Books 2010) Pg. 108.