In This Article
In This Article
Many little factoids say that humans and bananas share anywhere between 40 to 60 percent of the same DNA.1 While there is some truth to this statement and the sentiment it's trying to share, it's not 100 percent accurate. In fact, it's been kind of lost in translation for a bit.
Instead of sharing actual DNA with bananas, humans and bananas share about 40 to 60 percent of their genes, not DNA. Genes only make up about two percent of all your DNA, which makes much more sense why we don't look like bananas.1 Remember that genes do not equate DNA, even if they're often used interchangeably.
So it's not 40 to 60 percent identical DNA, but genes.
An experiment by Dr. Lawrence Brody observed that humans and bananas had several genetic counterparts that matched each other. The amino acid sequences in the human genome had similarities with their banana equivalents, leading to the figure that's often misspoken.1
When you look at how DNA is broken down, it makes more sense:1
So, really, when people quote the 40 to 60 percent figure, they mean 40 to 60 percent of the two percent of DNA that are your genes and code proteins. This is pretty much just one percent of human DNA.
It makes sense that most of our DNA doesn't actually match bananas, just a fraction of the very small part of our DNA that actually codes how we're made. Even if we took DNA tests with bananas, we wouldn't really see much on a large scale.
Humans sharing genes with bananas makes more sense the more you think about it. We actually share a lot with most living things and not just bananas.
Because most living things evolved from a common ancestor (a single-celled life form most commonly referred to LUCA, which stands for last universal common ancestor), it makes sense that a lot of them function similarly, which requires certain DNA sequences to work.2
We all share an ancestral gene, leading to how we live and similar biological function. Many living things that evolved from LUCA breathe oxygen, need to replicate DNA, divide cells to grow, and even consume sustenance (even if we consume nutrition in different ways).
Having similar sequencing in that manner makes sense, as we all thrive in similar ways—even if the methods differ a little.2
Diving even deeper, every living thing is made up of the same nucleic bases: adenine (A), thymine (T), guanine (G), and cytosine (C). With only four bases and a finite number of ways to sequence them (although big, it's finite), it's no wonder that many sequences and segments overlap, leading to genes in common among all living things.3
Within human genes, we have the same required functionality.
It's safe to say we share a lot of similarities with other living things. Here are a few examples:4
Remember that this genetic similarity is found in genes only, which is two percent of your actual DNA, potential genetic mutations aside. So even with such a huge genetic similarity, this is just a fraction of your actual DNA.
Even with close similarities, nothing is 100 percent identical. The entire genome cannot be the same for humans and bananas.
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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. These protein products from the genetic coding section of your DNA is what bears similarity with other living things.
Genes are part of your DNA, not all of it. They account for only two percent of a person’s DNA.5 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.
Of the 98 percent of our DNA that doesn't comprise protein-coding genes, eight to 20 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.1
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 and continue to probe into what the majority of our DNA actually does. So calling it "noncoding DNA" may be more accurate—and even then, we may not be fully sure that it doesn't code at all.
Some believe that they've lost function over the years, others think that they may serve a purpose we can't determine just yet. Some research is even looking into the possibility of silenced genetic material in our DNA or degraded genes that just haven't been discarded yet.
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 scientists believe that 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 According to them, this is the case for onions and other organisms that are slow to delete obsolete DNA.
This process doesn't affect survival, but it does result in organisms like onions having more DNA than others. On the other hand, following this logic, 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.
However, some scientists disagree with this idea. As more research goes into junk DNA and its function, the more hotly debated this topic becomes.
It's been observed in many species, although studies among all living things are still in their infancy. There is no clear answer yet, as some species discard DNA even in development, while others have not exhibited this behavior.
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.
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