You might have thought this was Lincoln's birthday, or just Presidents' Day weekend, but today is also the 207th anniversary of Charles Darwin’s birthday, otherwise known as Darwin Day.
I called Paul Norman, PhD — a senior research scientist who studies genetic variation, especially in human immune cells — and asked him how the theory of evolution has influenced his work. In a charming academic parry and thrust, he immediately pointed out to me that Darwin didn't come up with the theory of evolution.
The idea that living organisms can change, or evolve, over time had been around for a long time. Even the related idea that all organisms are related through "common descent" from a single ancient ancestor wasn't entirely new.
What Darwin did was come up with a mechanism — natural selection — that could explain how evolution could happen. And Darwin was able to persuade people that evolution is happening all around us and how it works. He left an indelible stamp on all of biology.
It turns out that Norman has a special connection to Darwin: The two scientists were born and raised just a mile apart in the same medieval town of Shrewsbury, where Darwin famously hiked, hunted and collected beetles.
Evolution informs the work that Norman does every day, as well as that of most people in the biological science, he says. “It’s rare that one person has such a long lasting influence.”
In our work, we find all these different variations of genes. By looking for the impact of natural selection, it enables us to focus on those changes that are important.
But Norman says his work has also informed his view of evolution.
It has made me realize that a major part of evolution is chance and finding the act of natural selection is a much, much harder thing to do than documenting cases of evolution.
I think that’s what made Darwin stand out. He achieved the harder part. I mean everybody could see that evolution was true, it was much harder to come up with the concept of natural selection.
I also talked with Parag Mallick, PhD,assistant professor of radiology, who studies the evolutionary ecology of cancer cells. He said cancers are ecosystems in the same way that a tropical rain forest is:
We used to think cancers were a large number of cells that were all the same. But now we know that the cells are all different. Some are different because they are genetically different, some are different because they live by a river — a blood vessel.
Chemotherapy drugs meant to cure cancer actually exert a selective pressure on populations of cancer cells, eliminating all the cells that are susceptible to the drugs, so only the resistant ones survive. "We know a drug will immediately shrink the tumor and then the cancer will come back bigger and stronger than ever."
The heavier the dose of the drug, the faster the cancer cells evolve. So instead of trying to kill as many cells as possible, Mallick and his colleagues are doing two things: trying to breed safer cancer cells — like so many domestic pigeons — and gently guiding the cells into the right kind of behavior by changing the ecosystem. It's a cutting edge approach to cancer therapy about which you can read more in a future issue of Inside Stanford Medicine.
Thanks, Darwin!
Previously: Rare African genes might reduce risks to pregnant women and their infants, From whence the big toe? Stanford researchers investigate the genetics of upright walking, The war within: In our aging bodies, the “fittest” stem cells may not be the ones that ensure our survival
Image by seriykotik1970
