A new study conducted by researchers at Ben-Gurion University of the Negev (BGU) suggests a link between cancer and human evolution.
Writing about their work in the journal Genome Research, the researchers say that gene mutations that once helped humans survive may increase the possibility for diseases, including cancer.
They came to this conclusion after studying mutations in the genome of the mitochondria, a part of every cell responsible for energy production that is passed exclusively from mothers to their children.
"Our ancestors responded to environmental changes, such as climate shift, with mutations that increased their chances of survival. But today, these same mutations predispose us toward complex diseases such as cancer," says Dr. Dan Mishmar, a molecular biologist from the Department of Life Sciences at BGU.
"Although mitochondria's role in the emergence of new species has been investigated recently, the idea that they are responsible for our susceptibility to illness startles many," Dr. Mishmar adds.
During the study, the research team analysed the genome mitochondria mutations from 98 unrelated individuals.
According to them, combinations of mutations tended to occur in tumours in precisely the same DNA building blocks that changed during evolution.
The researchers also observed that the mitochondrial genome of humans, who had migrated out of Africa to Europe 100,000 years ago, carried seven mutations found in almost all of today's Europeans.
"The concept that the same principles that drive evolution toward the emergence of new species govern the emergence of diseases is new.
A clinician looks at the genome of a tumor, or other disease, and compares it to the normal population, looking for new mutations that do not occur there. I assume the mutations are already part of the population and have had a survival function. When these same mutations reoccur in the correct environment, they can cause disease," Dr. Mishmar says.
The team say in the research article: "We show, strikingly, that evolution repeated itself in cancer.
If we better understand how evolution moved, we can understand the genetic basis of many complex disorders. Since mitochondria play a central role in disease, if we understand how they work and the way they changed our ability to survive in different conditions in ancient times, we can understand the mechanics of the disease.
And we'll understand a lot about the way certain people develop diseases and others have a lower tendency toward those same diseases. This may lead to new methods of disease prevention or cures."