How closely related are humans and chimpanzees?
Nearly entirely similar if you’re comparing chimp and human DNA.
Jane Goodall, the prolific researcher who likely spent more time with chimps than any other human, claims the similarities are staggering.
According to The Jane Goodall Institute of Canada, chimps and humans share 99 percent of their DNA. They consider chimps our “closest cousins in the animal kingdom.” The institute claims chimps are actually closer to humans than they are to gorillas, despite the similarities in their looks.
What are some of the most obvious similarities between chimps and humans?
Of course, Jane Goodall is not the only scientist that asserts human and chimp DNA is 98 to 99 percent similar. Most scientists subscribe to this theory.
But not everyone agrees with Goodall. Some consider the 99 percent estimate de-bunkable. Although the majority of the scientific community accepts Goodall’s estimate, some believe the relationship between humans and chimps is drastically affected by gene expression and not just DNA.
Those who dispute the 99 percent estimate point to the obvious differences between humans and chimps. These are the things we can see with our eyes just by looking at chimps and humans and comparing the two.
For example, most people know that genetics determines things like hair color or eye color. Humans are also about 38 percent taller and 80 percent heavier than chimps. Our lifespans are about 50 percent longer and our brains are approximately 400 percent larger.
There are also differences when it comes to human abilities. For example, chimps are unable to roll their eyes or tap their thumb and fingertips due to their thumbs’ location on their hands and the fact that they don’t have the same muscle dexterity as humans. They also have knees that point outward instead of forward. And while chimps are amazingly intelligent creatures, they aren’t able to accomplish the same intellectual feats as most humans.
Humans and chimps have different bone structures, brain types, and other major physiological parts.
What does all of this mean?
Some claim it proves the 99 percent is overestimated and the actual genetic similarity is closer to 85 to 90 percent. They claim that although this still seems high, it equates to more than 360 million genetic differences.
For starters, chimp and human DNA are two different sizes. Humans have 46 chromosomes and chimps have 48. Again, on the surface, this seems a lot closer than it actually is. In reality, it’s 3,096,649,726 base pairs in the human genome versus 3,309,577,922 base pairs in the chimpanzee genome.
According to them, it’s also important to consider how human and chimpanzee bodies just don’t “go together.” Humans don’t interbreed with chimps, nor do our body parts seem to be transferable. The few chimp-to-human organ transplants that have been attempted mostly failed within a few weeks. One chimp liver recipient lived for nine months after the procedure.
If you aren’t convinced of either side of the science, it might help to think of it this way:
You can have an Android phone or an iPhone. Both are phones and both can perform many similar tasks. But they are made up of two different software programs and have unique features.
But not everyone accepts this comparison or this breakdown of the DNA.
Opponents to the 99 percent number believe it’s also important to acknowledge that chimpanzees aren’t the only other living things that share genetic similarities with humans. As a matter of fact, we’re quite similar to things that are nothing like us at all, like bananas.
Again, there are similarities. Like all living things, we need oxygen, water, and a food source. But it doesn’t take a highly educated scientist to figure out that humans and bananas are generally not the same things.
And since organ transplant between humans and genetically less-similar animals have been successful, the organ transplant argument disproving similarity loses a great deal of its weight.
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Scientists acknowledge that while our DNA is similar to chimps, there are clearly differences in the two species. This could be due to gene expression and how junk DNA affects it.
Almost a decade ago at the American Society of Human Genetics 2012 meeting, Yoav Gilad, Ph.D., associate professor of human genetics at the University of Chicago reported that up to 40 percent of the differences between humans and chimps are in the expression or activity patterns of their genes and “can be explained by regulatory mechanisms that determine whether and how a gene's recipe for a protein is transcribed to the RNA molecule that carries the recipe instructions to the sites in cells where proteins are manufactured.”
Dr. Gilad’s work can help geneticists understand the uniqueness of humans and how exploring the various similarities and differences can go a long way in finding cures for diseases and improving human health.
According to Dr. Gilad, "Through inter-species' comparisons at the DNA sequence and expression levels, we hope to identify the genetic basis of human specific traits and in particular the genetic variations underlying the higher susceptibility to certain diseases such as malaria and cancer in humans than in non-human primates.”
A study conducted by researchers at the Georgia Institute of Technology further demonstrated the role of gene expression and how so-called junk DNA plays a role.
Long before DNA was an issue, scientists assumed that chimps and humans had different genetic makeups and were surprised to learn that the DNA sequences are extremely similar.
The GIT scientists started from here, on the basis the 99 percent DNA comparison is accurate, and asked the following:
If not DNA differences, what is responsible for the many morphological and behavioral differences between chimps and humans?
They concluded that it’s the insertion and deletion of large pieces of DNA close to the genes that are highly variable between chimps and humans. They believe it’s this issue that makes humans and chimps appear to have a lot less in common than they do biologically. Researchers confirmed that the DNA sequences are “nearly identical,” but there are gaps in the areas near these genes which affect the activation and expression of the genes.
This information was reported in Journal Mobile DNA.
So are humans and chimps genetically similar? The most up-to-date science confirms what Dr. Goodall realized decades ago: yes, but that doesn’t make them the same and it doesn’t mean there isn’t more to discover about the genetics of both species.
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“Humans, Chimpanzees and Monkeys Share DNA but Not Gene Regulatory Mechanisms.” ScienceDaily, 2012, www.sciencedaily.com/releases/2012/11/121106201124.htm. Accessed 20 Nov. 2019.
“10 Ways Chimps and Humans Are the Same.” Jane Goodall, 28 May 2019, janegoodall.ca/our-stories/10-ways/.
“Junk DNA’ Defines Differences between Humans and Chimps.” ScienceDaily, www.sciencedaily.com/releases/2011/10/111025122615.htm. Accessed 25 Feb. 2021.
“DNA Study Contradicts Human/Chimp Common Ancestry.” Www.icr.org, www.icr.org/article/dna-study-contradicts-human-chimp-common. Accessed 25 Feb. 2021.
Hansman, Heather. “The Future of Animal-To-Human Organ Transplants.” Smithsonian, Smithsonian.com, 17 Sept. 2015, www.smithsonianmag.com/innovation/future-animal-to-human-organ-transplants-180956402/.