aartadventure t1_jac3zfp wrote

It could be that most mutations do nothing bad, or that they end up being harmful in time, such as cancer. Here is one paper on the topic:


And yes, that was my point. Evolution tends to work slowly, over millions of years, due to the low chance of a beneficial mutation occurring, and then also being selected for in a given environment. And, since environments change, what was once beneficial, may end up becoming harmful over time.


aartadventure t1_jabnn6o wrote

Most mutations are not good, or downright lethal, leading to miscarriage, cancer and other awful outcomes. Especially in multicellular organisms, advantageous mutations occur quite rarely. That organism also has to be lucky enough to survive long enough to reproduce (you might have an incredibly advantageous mutation but just be unlucky and get struck by lightning before you reproduce for example). It may be something more akin to flipping 50 or 100 heads in a row.


aartadventure t1_jabnb5b wrote

Even recessive traits are selected for in the natural environment over time. However, they remain recessive for various reasons. This could include the recessive trait being advantageous in certain circumstances, but not others. Or that is only an advantage if other traits are also expressed at the same time. Many times a recessive trait can be an advantage but exacts a biological cost as well. If these traits remain recessive, evolutionary pressures cause them to become more common in the "required" circumstances, while allowing them to swiftly become less common when the environment is not suitable for that trait.