Illustration by Ahmed Bilal

Why am I not a fly?

60% of the human genome overlaps with the fruit fly genome. Here is how studying these similarities is helping our understanding of the human body.

Nov 7, 2022

The fly, more specifically the fruit fly, is often talked about in biological and genetic research. When I read a few scientific books in school, I was dumbfounded by the fact that 60 percent of the human genome overlaps with the fruit fly genome.
“So what stopped me from being a fly?” were my first thoughts. I know, a weird question, but this is a question that is still being researched. Since not all the matching DNA has a known use, here are some theories and information regarding the comparison of fruit fly and human DNA.
Firstly, the fruit fly has DNA known to cause brain circuit functions similar to DNA in human brains. There are some regulatory proteins — proteins that control how our body or cells work — that affect the working of our brain, and especially some which affect our behavior. A collaborative study done by four institutions across the world, including universities, talks about how mutations in these regulatory genes showed impairment of behavior. This hints at some advancements they have made in locating genes in the brain that cause certain mental health disorders, a link that was thought not to be true.
Another similarity is that both flies and humans have cells that have DNA coding for important proteins to help our cells maintain a 24-hour cell clock called the circadian rhythm. Michael W. Young, a 2017 Nobel Prize winner in medicine, and two other researchers experimented with fruit flies to find a protein that degrades in their cells during the day and is basically remade and restocked during the night. So, by studying fly cell clock proteins, we can essentially locate our cell clock proteins and find out more about how they work.
The actual function of all the 60 percent of common DNA between us and fruit flies is not known. We do know, however, that this 60 percent of common DNA contains 75 percent of our disease-causing genes and 90 percent of our cancer-causing genes. By studying and using the fruit fly as a model for specific cancers and diseases, scientists can help add to further treatments and help cure patients better and more efficiently by using CRISPR, a gene editing tool that cuts DNA at specific points, and newer gene technology. Also, just the basic cell growth and division of genes are quite similar in a lot of organisms, so it is no surprise that we have those just like flies, and they account for a lot of the 60 percent of our DNA that we share with flies.
However, fruit flies do not have certain features that cause gene regulation in humans, hence they are genetically different as different proteins are expressed in their bodies.
Gene regulation is a process that regularly occurs in our bodies where a regulatory protein is produced in our cells, which increases or decreases the production of other proteins (like enzymes for digesting food or structural proteins like keratin in the skin and hair). The different proteins perform different functions, and these different functions lead to the formation of different organisms. One example is the type of proteins that form wings and are not present in humans but are coded for in fruit fly DNA. This discovery gives more evidence to a broader theory of evolution as proposed in their report, as changes in regulatory genes could cause changes in the structures of organisms, and hence entire organisms.
In essence, the fruit fly has a lot of genetic similarities and differences with humans, and this has been used to study them as a model for our understanding of the human body and its various life processes. Some of the research, if not most, is slowly helping us develop drugs that target cancer and neurodivergent conditions. And as disappointing as it is that I’m not a fly, the sheer amount of similarities between humans and flies is quite shocking. Now, did you know that we also share 50-60 percent of our DNA with bananas?
Iman Lalani is Deputy Columns Editor. Email them at
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