Want to understand better how human traits are passed on? Just study the fruit fly.
Getting fruit flies drunk might sound silly, but it's an important part of Dr. Trudy Mackay's research.
Enter Mackay's lab at NC State University, and you'll find multiple columns stretching from floor to ceiling with alcohol vapor running through them. If you look real close, you'll see the fruit flies in these "inebriometers" partying hard — getting hyperactive, falling all over the place, and then eventually just passing out drunk.
The thing is, that's exactly how a human would react to alcohol. So does this make fruit flies more human? Obviously not. But it does illustrate one of the many traits and characteristics that we have in common with the humble (and occasionally tipsy) fruit fly.
When Mackay read a study in 2000 that said 70-75% of human genes have equivalents in the fruit fly, she knew there was more to be learned about humans.
In fact, the research she gathers from fruit flies can usually translate to humans. And in some cases, what'll make a fruit fly sick will make a human sick as well — meaning we can potentially learn a lot about serious diseases from observing fruit flies.
In the case of the alcohol sensitivity, Mackay and her team identified a gene in the flies called "malic enzyme" that was strongly affected by the alcohol. Then when they surveyed humans on their drinking habits, they found that those who consume alcohol had similar results in the same corresponding gene. It's a huge step in understanding how alcohol affects us, but what's key is finding other variants like malic enzyme and observing how they interact with each other.
"This is where we’re going in the future," adds Mackay. "What we would like to know is how the variants combine together to affect risk."
So why test fruit flies in the lab and not, you know, a lab rat?
"They're actually an odd but very good model of human complex traits," Mackay says. "In fact, many of the pathways that we know are involved in cancer, heart disease, other human complex diseases actually have names from flies — where they were first discovered."
Mackay also notes that there are a couple of advantages to using the flies instead of the more common lab mammals. "One is their very short lifespan," she says. Fruit flies don't live all that long, so it's easier to see how the traits they observe are passed from one generation to the next. It also makes it easier to study just that — lifespan.
"The other is that we have community resources that have been built up over many, many decades," adds Mackay. "A whole host of technological advances that we can use to study traits that are relevant to human health."
In fact, one of the most important resources around is one that she created. The Drosophila Genetic Reference Panel (DGRP), a collection of 200 different genetic fruit fly lines, allows other scientists to conduct their own research and compare their trait results with the catalog Mackay has provided. That helped earn Mackay the esteemed Wolf Prize in Agriculture, an award that's known to be an indicator of Nobel Prize winners.
There's still a lot of work left to be done, but that only pushes Mackay even more.
Yes, it's pretty awesome that we have a lot in common with fruit flies. But in the grand scheme of things, it's about so much more than that. "What I think is most important are the general principles of complex trait inheritance that we’ve discovered that I very much think is applied to the same general principles in humans," Mackay notes.
That's why Mackay continues to apply her research to understanding a number of different causes — whether it's glaucoma, aggression, or stress resistance in humans. At the end of the day, it's all about gathering as much information as possible to put the pieces together.
"You can think of it as, the studies we've done up to now is giving us a parts list," Mackay says. "And what we need to do is figure out how those parts go together."
It's a long (and unpredictable) road ahead, but it's one that Mackay would gladly go down anytime. When asked about what inspires her to keep pushing the field forward, Mackay didn't even hesitate.
"The same as any scientist," she says. "Curiosity about the natural world."
Feeling curious yourself? Check out the video below to learn more about Dr. Trudy Mackay's groundbreaking work: