In This Article
In This Article
Surprisingly, humans and bananas share about 40 to 60 percent of the same DNA. But this doesn’t mean humans are bananas or vice versa, although it indicates significant genetic similarities.
This discovery of shared DNA sequences occurred at the National Human Genome Research Institute in 2013. Information from the study was included in The Animated Genome, a Smithsonian Museum of Natural History video.
To understand how humans and bananas can share DNA while appearing vastly different, we must first explore the distinction between DNA and protein products.
According to scientists, DNA or genetic code serves as a blueprint for an organism. On the other hand, protein products are the structures and functions that result from this blueprint.
One way to conceptualize the difference between human DNA and banana DNA is to compare them to two different styles of houses. Human DNA would be a colonial-style house, while banana DNA might be comparable to a bungalow-style house.
Both styles are houses with similarities—they are structures that can be occupied and may contain the same things. But they also have distinct differences.
DNA serves as a blueprint for an organism, while protein products are the structures and functions that result from this blueprint. This explains how humans and bananas can share DNA but still have distinct differences.
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Genes account for only 2 percent of a person’s DNA.1 When scientists discovered the link between bananas and humans, they analyzed the sequences of genes in a banana.
Then, they predicted the sequences of all proteins that would be made from those genes. They also performed the same analysis for genes in humans.
Next, they compared the protein sequences from banana genes to human genes. They conducted over 4 million comparisons and found 7,000 matches.
They averaged that out and concluded that about 40 percent of our protein products are similar to banana protein products. That leaves a significant portion of genes that don’t match between bananas and humans, but there are still many that do.
Scientists analyzed the genetic sequences in a banana and predicted all possible protein sequences from those genes. They did the same with human genes, after which they concluded that about 40 percent of our protein products are similar to banana protein products.
The fact that humans and bananas share DNA may seem surprising, but it shouldn’t be. Bananas and humans are both living organisms, which means there is bound to be a genetic connection.
For example, both bananas and humans consume oxygen, are affected by sunlight and water, and grow. There's a similarity between humans and other living things.
Humans share about 85 percent of our DNA with mice and over 60 percent with fruit flies.2,3 Despite our vastly different evolutionary paths, there is a common signature in the genome.
This means if you trace back far enough through evolution, you’ll find a shared ancestor. A single-cell organism that lived billions of years before us contained genes that were passed along to us, as well as to fruit flies, mice, and bananas.
The genetic connection between all living things can be traced through evolution. A single-cell organism billions of years ago contained genes that were passed along to humans, bananas, fruit flies, and other organisms.
Of the 98 percent of our DNA that doesn't comprise protein-coding genes, eight percent determines if genes that do the coding will be turned on or off. The remaining 90 percent has unknown functions or no longer functions.4
Scientists sometimes call this 90 percent "dead genes" or "junk DNA." Despite that name, researchers are discovering that some of this junk DNA does serve a function.5
98 percent of our DNA are non-coding genes. Eight percent determine whether the coding will be turned on or off. The remaining 90 percent are what scientists call dead genes or junk DNA, which may have unknown functions.
People often think that more complex organisms must have more complex DNA. Surprisingly, that's not always true.
For example, onions have about 12 times more DNA than humans, and amoebas have a staggering 200 times more DNA than us.
As we mentioned before, not all DNA is functional or "junk DNA." Some organisms get rid of their junk DNA faster than others. When an organism is slow at discarding junk DNA and replacing it with new junk, its DNA quantity increases.6
This process doesn't affect survival, but it does result in organisms like onions having more DNA than others. On the other hand, fruit flies efficiently clear their junk DNA, leaving them with less DNA than humans.
The quantity of DNA an organism has doesn't determine its evolutionary advancement. If it did, onions would be more evolved than humans and fruit flies.
An organism's DNA quantity increases when it is slow at discarding junk DNA and replacing it with new ones. This is how organisms like onions and amoeba have more DNA than humans.
Even among similar species of organisms, the process of discarding junk DNA can vary. For instance, among insects, crickets have about 11 times more genetic material than fruit flies.
Crickets lose junk DNA about 40 times more slowly than fruit flies do.
Researchers admit that tracking the discarding of junk DNA isn't an exact science. They need to make educated guesses about which DNA is considered junk and then follow this process over millions of years.
Some experts disagree on whether specific DNA is really junk or if it has a purpose.
Despite these challenges, researchers are confident enough in their tracking method to apply it to the genomes of many species.
Although the reasons for varying discard efficiency among organisms are still unclear, scientists agree that this process doesn't impact a species' ability to survive.
The junk DNA discarding process can be different even among similar species of organisms. Researchers admit that tracking the discarding of junk DNA isn't an exact science. But they are confident enough in their tracking method to apply it to the genomes of many species.
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