Is it true that humans share 50% of the same DNA as bananas?

You might have come across the fascinating tidbit that humans and bananas share 50% (or even 60%) of the same DNA—whether at a party, during trivia, or in a "Dude Perfect" video. It sounds odd, considering the stark differences between a human and a banana, starting with the fact that one is a living being and the other is a plant! However, there is some truth to this claim, although it’s not the full picture.

This information likely stems from a project conducted by the National Human Genome Research Institute in 2013, although similar studies may have been conducted elsewhere. The research was spearheaded by genetics expert Dr. Lawrence Brody, though interestingly, Brody notes that this experiment wasn’t published like most scientific studies. Instead, it was designed for an educational Smithsonian Museum of Natural History video titled "The Animated Genome." The video mentioned that the DNA shared between a human and a banana is "41 percent similar."

To understand how this connection was discovered, we spoke directly with Dr. Brody. He chuckled, saying, "It's funny how it's gotten legs," referring to the growing popularity of the banana/human DNA comparison.

Human vs. Banana

To truly understand, we need to distinguish between DNA and protein products. Brody explains it best by comparing DNA to the blueprint of a house and protein products to the completed house. While the house's structure is similar (think plumbing, bathrooms, kitchen), the end result is clearly different. That’s the analogy for human and banana DNA—similar blueprints, but very different outcomes.

Another key point is that genes, the DNA segments responsible for coding proteins, make up only about 2 percent of your total DNA.

In this experiment, the researchers first analyzed the gene sequences of a typical banana genome. "We then used these sequences to predict the amino acid sequence of all the proteins that would result from those genes," Brody explains. The predicted protein sequences were recorded in a file. "We repeated the same process for all human genes."

The researchers then compared the protein sequences from each banana gene to every human gene. "The program looks at how similar the banana gene sequences are to the human ones," Brody explains, noting that similarity scores can range from 0 to 100 percent. "The program kept only those matches that were more similar than what would occur by chance." This process continued, examining each gene one by one.

In total, more than 4 million comparisons were made, leading to about 7,000 strong matches between the two genomes. Then, the similarity percentages for each of these matches were averaged. "This gave us an average result of about 40 percent," Brody says. "This is the average similarity between proteins, not the genes themselves." Gene products or proteins are the biological materials that result when a gene becomes functional. "Naturally, there are many genes in our genome that don’t have a counterpart in the banana genome, and vice versa."

If that sounds a bit complex, here's a simplified explanation: The scientists compared each banana gene to human genes one by one, measuring the similarity (genes present in one but not the other weren’t counted). Around 60 percent of human genes have a recognizable counterpart in the banana genome! "For those 60 percent, the proteins they encode are about 40 percent identical when comparing the human protein's amino acid sequence to that of the equivalent protein in the banana," Brody adds.

It may seem surprising that such a high number of genes are shared between humans and bananas, given how different they are. But in reality, it makes sense. "If you think about the functions we share with bananas, like breathing oxygen, many of those genes are fundamental to life," Brody points out.

We're All Relatives

When people talk about the "similarity of DNA" at 50 percent, they’re actually referring to the similarity of gene products, not the DNA itself. "It’s a small mistake," Dr. Brody clarifies. "The takeaway here is that we share something in common with bananas, potatoes, and even pine trees. That part is accurate. The confusion about gene products or DNA is understandable though," he adds.

If a scientist were to compare the DNA of a banana with that of a human, it wouldn't match up directly. "You share 50 percent of your DNA with each of your parents. But with bananas, we share around 50 percent of our genes, which actually amounts to only about 1 percent of our DNA," explains Mike Francis, a Ph.D. student in bioinformatics at the University of Georgia.

As previously mentioned, genes make up only 2 percent of your DNA. So what’s the other 98 percent? Eight percent of the remaining DNA regulates genes (deciding whether they should be active or not). The rest, about 90 percent, seems to have unknown or evolutionary remnants of functions. "This part of the DNA was once labeled 'junk DNA' because it was thought to be inactive. I’m cautious about using the term 'junk DNA,' as each year we discover more that actually serves a function," says Francis.

Humans don’t just share a large portion of DNA with bananas – we also share 85 percent with mice and 61 percent with fruit flies. "The fascinating part is that even though these species are far apart in evolutionary history, we can still detect a common signature in the genome of an ancient ancestor," Brody notes. "These genes were crucial for cell survival and reproduction billions of years ago and have been preserved in us and plants."

Francis points out that humans likely share about 1 percent of their DNA with other fruits as well. "This is because all life on Earth evolved from a single cell that emerged roughly 1.6 billion years ago," he says. "In a way, we are all related!"