Do Humans and Bananas Really Share Half Their DNA?
During Party conversation or a Trivia night you may have heard the fun little fact that humans and Bananas Sheriff Fifty or even sixty percent of the same DNA there it seems to be a lot of differences though between a person and a piece of yellow fruit starting with the fact that one is an animal and the other is a plant but actually there is some truth to that startling statistic but it's not the whole truth. This urban legend of sorts likely originated from a program run by the National Human Genome Research Institute back in two thousand thirteen. Although similar similar data may have been run elsewhere genetics expert. Dr Laurence Brodie at his colleagues generated some banana human information to be included as part of an Educational National Smithsonian Museum of Natural History video called the animated genome that video noted that DNA between a human and a banana is forty one percent similar so in order to find out how this similarity was determined. We talked with Dr Brody himself. He explained that. I it's important to understand the difference. Prince between DNA and protein products. You can think of DNA as the blueprint of a house and protein products the actual house because all of the information is in there Then think of human DNA is the blueprint for a ranch home and banana. DNA is that of a condo in each house. A bunch of things are similar. The plumbing bathrooms kitchen and products are both quite different. That's how it works with humans versus just about everything else from bananas to chimpanzees. The second thing to keep in mind is that genes which are the regions of DNA that code for these proteins. Only make up about two percent of your DNA in order to compare humans and bananas scientists. I looked at the sequences of jeans and a typical banana. Genome Brody said we then used these DNA sequences to predict the amino acid said sequence of all the proteins that would be made from those genes. We then did the same process for all human genes. All of the protein sequences were placed in a file file next. The scientists compared the protein sequence from each banana gene to every human. Jean Brodie said the program compares. How similar the sequence of the banana genes are to each human? Gene Program. Kept any matches that were more similar than one would expect by chance. The program continued doing this gene by gene seen all told more than four million comparisons were done resulting in about seven thousand best hits between the two genomes then the percent similarity score score for each of those hits was averaged Brady said this gave us the result of about forty percent this is the average similarity between proteins gene products. Not What genes gene products or proteins are the biochemical material resulting from Jean becoming functional. Brody continued of course there are many many genes in our genome that do not have a recognizable counterpart in the banana genome. Ns Versa in case. That's a bit difficult to chew and swallow. Let's let's break it down. Essentially they took all of the banana jeans and compared them one at a time to human genes from that they called a degree of similarity. If the banana had the gene. But the human didn't that didn't get counted and about sixty percents jeans have a recognizable counterpart in the Banana Genome Brady explained and of those sixty percent. The proteins encoded by them are roughly forty percent identical when we compare the amino acid sequence of the human protein twins equivalent in the banana. Uh it may seem shocking that so many genes and so many of the proteins that they create are similar in to such vastly different beings as a person in a banana. But when you think about it. It's not that shocking. Brody explained if you think about what we do for living and what a banana does. There's a lot of things we do. The same way. Like consuming oxygen a lot of those genes are just fundamental to life so when people repeat the percentages being a similarity of DNA. Actually actually what the research looked at was the similarity of gene products. Brody reassured US. It's a pretty minor mistake. The kernel that you would take home is that we have something in common with a banana and a potato and the pine tree that part is true. The fine points about the gene products or the DNA is easy to see how that would get translated incorrectly so the scientists looked at the DNA sequence of a banana and compared it with the DNA of human it would not align. We also spoke by email with Mike Francis a PhD student in Bioinformatics at the University of Georgia. He explained you share fifty percent of your DNA with each of your parents but with bananas as we share about fifty percent of our genes as we said earlier genes make up just two percent of your DNA. So what's the other ninety eight percent made up of well. Eight percent of the rest of your DNA regulates genes as to whether a gene should be turned on or off other ninety percent appears to have unknown functions or functions that have been lost through evolution. Francis said these unknown sections of DNA used to commonly called junk DNA because it was thought to do nothing I hesitate to use the phrase junkie because each year. It seems we realize more of this junk is actually functional. Humans don't just share a high percentage of protein protein encoding genes with bananas. We also share eighty five percent of those genes with a mouse and we share sixty one percent of disease causing genes with a fruit fly. Brody Brody said the remarkable thing is that despite being very far apart in evolutionary time we can still find a common signature in the genome of a common ancestor. These are preserved served because the genome of an organism that lived billions of years ago contained genes. That helped cells live and reproduce. Those same jeans are preserved in US and plants Francis added that humans likely share about one percent of their DNA with other as well. He said this is because all life that exists on earth has evolved from a single cell fell originated about one point. Six billion years ago in a sense. We're all relatives