Why do research on model organisms?

Author for this post: Travis Parsons, Ph.D Candidate

 

Rather than perform experiments on humans, most research is focused on using other organisms as models for human biology. These organisms include the following:

Drosophila melanogaster (fruit flies)

Xenopus laevis (African clawed frog)

Danio Rerio (zebrafish)

Saccharomyces cerevisiae (yeast)

Caenorhabditis elegans (nematode)

Mus musculus (mouse)

Arabidopsis thaliana (Arabidopsis)

… and many more note listed here. (Link to Wikipedia list). If you would like to know more about why we use model organisms in general, see our earlier post here.

 

So just how good are these model organisms for approximating human health? The truth is that these models are extremely good models for answering questions about human biology, and about biology in general. The reason why is that all organisms share ancestry with one another through the process known as evolution. Many people are often confused about evolution’s basic premise. Evolution does not attempt to explain how life on Earth started, it only seeks to explain how life has evolved since it began. Scientists still do not know how life began, and evolution stands independently of this unsolved mystery.

On one level, this means that all organisms on Earth are directly related. On another level, this means that their molecular biology is also very similar (or “conserved”). This is a key concept to grasp when answering the question of how adequate these models are for human health. You may think you are pretty different from a mouse, but do you know how similar your liver cells are to a mouse’s liver cells? Or how similar a fruit fly’s insulin is to your insulin? How different would you believe your insulin is if we were to tell you that humans respond perfectly well to a fruit fly’s insulin and a fruit fly responds equivalently to human insulin? The two are interchangeable! Despite the myriads of differences between species, the cells that comprise these organisms are extremely similar. They attach to each other in similar ways, they talk to each other with similar signals, and they carry out the same basic cellular activities. Any modern FDA approved medicine you have ever taken in your life was given to model organisms first before human testing. Thanks to the evolutionary conservation between these organisms and humans, we can use them (responsibly, with proper research ethics and humane protocols in place) to create life saving pharmaceuticals, understand how different aspects of biology lead to disease, and how life as we know it works.

Unfortunately, more and more governmental science funding is going towards human-centric research and every year model organism researchers are receiving lesser and lesser funding. Despite the recent advances in human research, many human-only studies are less powerful than studies done on model organisms. Humans are complex, lead long lives, are subject to many environmental factors that affect their biology, and are impossible to control properly in studies (Example: It’s easy to give mice a fixed diet and see what happens… it is impossible to give human test subjects a strict diet and have them follow it for 5+ years). One recent technique has been to take two vastly different humans (for example, some one who is obese and some one who is extremely thin) and look for what genetic differences exist between them. It has turned out that genes are more variable than previously appreciated, and there are hundreds of differences that could explain these differences in biology. The only way to test which ones matter is to explore them in model organisms. It is important to note, however, that this a two way street. Because biology is so variable, there is also no way model organisms can ever replace human research. All findings in model organisms must be tested in humans or human cell lines in order to be applied as human medicine. But the truth is that the basic science is much more powerfully and convincingly done in model organisms before the successes are carried further to human trials. Hopefully this post begins to explain why both basic science research and model organism research are critical to improving human medicine and health – there is no faster or more powerful way to research biology and apply it towards humans. Our blog will continue to have further discussions on this topic as we get more in depth about these specific ideas. Please continue to support funding for basic scientific research and model organisms. Our findings will continue to pave the way for human medical scientists to bring these findings to clinical trials, and eventually to you and your family.