Human And Chimp DNA Similarity—Not What We’ve Been Led To Believe
Bodie Hodge, M.Sc., B.Sc., PEI
Biblical Authority Ministries, December 18, 2024
You’ve probably heard that humans and chimps are somewhere
around 98% similar in our genetic makeup. There is a huge problem with this
though. The claim that humans and chimpanzees share 98% of their DNA is an
oversimplification of a comparison of “cherry-picked” segments of DNA and thus
a misrepresentation of the actual genetic evidence. The amount of similarity,
after further research is much, much larger than 2%.
Is Similarity A Good Or Bad Find?
There is similarity though, but not 98%. That number that
keeps getting thrown out there. What might surprise you though is that
creationists expect a significant amount of similarity.
The fact that God created man with a physiology similar to
mammals should automatically clue anyone off that there is going to be
similarity. Of course, man is not an animal; and even though our bodies are
made from dust with a physiology similar to certain animals, man is made in a
more unique way—in the image of an eternal, ruling, logical, knowledgeable,
wise, and loving God.
The fact that we discovered similarity in our DNA (with
hosts of other animals and plants too!) is an amazing confirmation of what we
expect to find in light of Scripture. God is the brilliant designer—the
greatest of engineers!
The test of a great engineer is to be able to reuse ideas,
designs, materials, and parts in multiple applications—sometimes with slight
modifications to the specific use. Seeing how God did this across the board
with plants as well as with animal life—dwarfs anything that man could do. This
excites me as a creationist.
Nevertheless, we need to be honest with the genetic data
about similarity—there is some, but definitely not 98%. So, what is it? We’ll
get to that but first, you need to understand where the 98% number came
from, then you’ll be able to see why the new, more thorough, data is so
powerful!
Where Did The 98% Number Come From?
By 1990, the claim of 98% similarity between humans and
chimps was engrained in society. According to J. Cohen, it began with A. Wilson
and M. King in the mid-1970s.[1]
Other built on this.[2]
The 98% claim further took the world by storm when the human
and chimp DNA was mapped and researchers were arguing genetically that it was
96-99%.[3]
However, the 98% similarity statistic arises from a flawed
methodology that assumes the religion of secular humanism to be true from the
outset (which holds to evolution). As a result, when secular scientists compare
human and chimp genomes, they align sequences based on similarity and
neglect the rest. Yes, you read that right!
Follow me here, significant portions of the genomes do not
align well and are often excluded from the comparisons. This
cherry-picking of data creates an inflated measure of similarity.
For example:
- Only
the most comparable DNA sections (exons or protein-coding regions) were
often compared.
- “Non-alignable”
regions, which can differ significantly, were excluded, leading to an
incomplete picture.
Thus, the comparison isn't a direct measurement of the entire
genomes. In other words, if you ignore sections that aren’t similar and just
look at sections that are, then you are not being true to the % similarity. Let
me do an analogy to give you an idea of what is going on.
Let’s say you are in a grocery shop
and you are going to compare two different cartons of eggs. When you look at
the first dozen, all the eggs look good and none are cracked. Then you look at
the second dozen and 5 are cracked and messy.
Now, if the grocer came up and said
they are basically the same and offers to show you by closely comparing 6 good
eggs from both containers to convince you that they are basically the same and
then tries to sell you the dozen that contains the 5 broken eggs. Would you buy
that argument (and that dozen eggs with 5 broken)? The grocer did an
oversimplification and misrepresentation of the entire carton of eggs.
In the same way, the claim that humans and chimpanzees share
98% of their entire genome is an oversimplification and
misrepresentation of genetic evidence.
The Entire Genome Comparisons
When the entire genomes of
humans and chimpanzees were finally examined, the differences became far more than
the often-cited 1–2%. There are major differences in structure such gene order,
chromosome structure, indels, and genome length but are ignored in these early
percentage-based similarity claims.
The 2005 analysis of the chimpanzee genome also pointed out
that when considering the things that were initially not analyzed (e.g., insertions,
deletions, and duplications), the differences between humans and chimps add up
to be closer to 15% or more.[4]
Stop for a moment and ponder this—this is not a 3% difference
or even a 4% difference, but a massive 15% difference! The initial claims of
98% similar were off by at least 13% by the evolutionists own reckoning.
Yes, breathe this in for a moment and notice how the secular worldview
influenced an entire generation to believe that humans and chimps were 98% when
it wasn’t even close. By this study, 85% similar (could be more!). That is
huge.
One should also highlight the importance of considering functional
differences in the genome. Even small genetic differences can lead to major
distinctions in traits, behavior, and biology. For example, regulatory DNA
regions, which control how genes are expressed, show major differences between
humans and chimps. Also, the expression and timing of genes involved in brain
development, speech, and locomotion vary a lot.
To put this into perspective, even if there were a “superficial
similarity” of 98% in sequences, the function of that DNA is what
matters. Humans and chimps are fundamentally distinct creatures in terms of
biological complexity, cognition, and design.
One area where differences are especially dramatic is the Y
chromosome—obviously talking males here. Researchers have shown in their studies
that the human Y chromosome and chimp Y chromosome differ considerably—by up to
30–50% in sequence and structure.[5]
This utterly destroys the idea of near-total genetic similarity. We are now
talking about 50-70% differences in the y chromosomes. X chromosomes don’t
fare much better when compared. Geneticist Jeffry Tompkins writes:
“Only 69% of the chimpanzee X
chromosome was similar to human and only 43% of the Y chromosome. Genome-wide,
only 70% of the chimpanzee DNA was similar to human under the most optimal
sequence-slice conditions.”[6]
After the latest round of research, the overall average
DNA similarity between humans and chimps is sitting at about 70%.[7]
That 30% dissimilar is like an avalanche on the evolutionary claims of close
similarity. This is massive dissimilarity throws a monkey wrench into the
evolutionary claim of a close human-chimp ancestor.
Concluding Remarks
The oft-cited 98% similarity between human and chimpanzee
DNA is a result of selective comparisons, “leaving-out” large genomic
differences, and “incorrect-method-based” assumptions that favor evolutionary
conclusions.
When the entire genome is considered, humans and chimps are
far less similar, both genetically and functionally (only 70% similar).
These findings actually more in line with what we expect with the biblical view
that humans are uniquely created in God's image, distinct from animals.
To better understand the details of this discussion, I
highly recommend that you read:
1. D. DeWitt What
About the Similarity Between Human and Chimp DNA?, The New Answers Book 3
(Ham and Hodge gen. eds.), January 14, 2014.
2. J. Bergman and J. Tomkins Is the human
genome nearly identical to chimpanzee?—a reassessment of the literature, Journal
of Creation 26(1):54–60, April, 2012
3. J. Tompkins Comprehensive
Analysis of Chimpanzee and Human Chromosomes Reveals Average DNA Similarity of
70%, Answers Research Journal 6 (2013): 63–69, February 20, 2013.
[1] J. Cohen, Relative differences: the myth of 1%, Science
Magazine 316:1836, June, 29, 2007.
[2] Hoyer et al., Examination of hominid evolution by DNA sequence homology, Journal of Human Evolution 1:645–649, 1972; C. Sibley and J. Ahlquist, The phylogeny of the hominoid primates, as indicated by DNA-DNA hybridization, Journal of Molecular Evolution 20:2–15, 1984; C. Sibley, DNA hybridization evidence of hominoid phylogeny: a reanalysis of the data, Journal of Molecular Evolution 30:202–236, 1990.
[3] Broad
Institute Communications, Comparison of human and chimpanzee genomes reveals
striking similarities and differences, Broad Institute, August 31, 2005,
https://www.broadinstitute.org/news/comparison-human-and-chimpanzee-genomes-reveals-striking-similarities-and-differences;
The Chimpanzee Sequencing and Analysis Consortium. Initial sequence
of the chimpanzee genome and comparison with the human genome. Nature. 437:69-87.
DOI:10.1038/nature04072.
[4] The
Chimpanzee Sequencing and Analysis Consortium. Initial sequence
of the chimpanzee genome and comparison with the human genome. Nature. 437:69-87.
DOI:10.1038/nature04072.
[5] J.
Tompkins Comprehensive
Analysis of Chimpanzee and Human Chromosomes Reveals Average DNA Similarity of
70%, Answers Research Journal 6 (2013): 63–69, February 20, 2013.
[6]
Ibid.
[7]
Ibid.
