Mutation rates evolve depending on selective pressures and the environment. Based on Darwins theory of natural selection, a higher more beneficial mutation rate would increase a species fitness, therefore increasing the ability to reproduce and evolve throughout generations. What I originally thought about when I first looked at this question, was the increase of bad mutations. When it comes to humans we want to avoid mutations in our cells, because most lead to cancer. Our environment is filled with stressors that affect our body. Some environmental pressures we choose to expose ourselves to: smoking, tanning beds, drinking, and our diet can all lead to cancerous mutations. Then we have the exposure to things we can't really control in our everyday lives: sun exposure, pollution, chemicals in products that we consume almost everyday. This is also not including family genetics that can also influence mutations. This all now seems terrifying, but it also fascinates me. In America the prevalence of cancer is 5.5% of our population, and most of those people are older. Their cells just couldn't keep up anymore and made a mistake.
Now I know what you're thinking, wow that is really sad and depressing, but in my mind I am baffled by how cancer rates are not higher! Cells in our intestinal tract replace themselves within a few days, while other cells like fat cells can take up to 10 years. A low mutation rate would be beneficial when the organism has a simple body unable to correct the mistakes made cells, but our body is complex and capable of amazing things. Our cells mutate frequently, but our bodies are usually able to repair themselves. We have a high mutation rate (that is not beneficial), but a strong ability to fix ourselves. So my question that I pose to my two reviewers is this...
- Would you consider our mutation rate high or low?
- Does mutation rate only refer to those mutations that are successful?
Now I know what you're thinking, wow that is really sad and depressing, but in my mind I am baffled by how cancer rates are not higher! Cells in our intestinal tract replace themselves within a few days, while other cells like fat cells can take up to 10 years. A low mutation rate would be beneficial when the organism has a simple body unable to correct the mistakes made cells, but our body is complex and capable of amazing things. Our cells mutate frequently, but our bodies are usually able to repair themselves. We have a high mutation rate (that is not beneficial), but a strong ability to fix ourselves. So my question that I pose to my two reviewers is this...
- Would you consider our mutation rate high or low?
- Does mutation rate only refer to those mutations that are successful?
https://ourworldindata.org/cancer
Hi Mary! I enjoyed reading your blog post and love how you brought in the topic of cancer because this is something that also fascinates me. I am also surprised that our cancer rate is not higher because I do believe our mutation rate is high and that can lead to a lot of mistakes. I agree with your explanation about how our bodies are complex and able to fix most mistakes compared to a smaller, less complex species. I am unsure how to answer your second question because I do not know what you define a 'successful' mutation as. I would say that mutation rate refers to the mutations that are visible and able to be tracked, but there are mutations that do not show up phenotypically. Mutation rates are lower than what they actually are because it is nearly impossible to track every mutation in every generation. If you consider a successful mutation to be one that is visible, then I would say yes to your second question.
ReplyDeleteHi Mary,
ReplyDeleteI too thought of only bad mutations and didn't even think about how there could be good mutations. Like Lola said, I think bringing up the topic of cancer and humans was a really good idea. As for your question, I think initially mutation rates in us are pretty high but our cells do a really good job of fixing them before it is too late, so not very many are actually seen or "successful."
I feel the rate of mutation in humans is low. There is an incredible amount of cellular mechanisms being employed in the human body, all happening in our trillions of cells, so I feel it is inevitable. Yet, I do agree in our cells own repair mechanisms are saving us from a higher incidence of cancer! This second question is tricky and I think both are true, but if we are wanting to utilize data referring to said mutation rates we must be more specific. I like that you posted questions directly to your reviewers and I will have to steal that idea from you in my next post!
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