According to C.R. Darwin, genetic variation allows evolution to create a better life form through trial and error. Without variety, there are no favourites, without favourites, there's no life. Unpredictability and variation are major survival assets.
I believe that cancer, our biggest predator, is a ticking time bomb that provides variability to our lifespans, assuring that some will get it, some will not and people with it will die at different times. Not predictable, somehow giving us more variation even at the cost of our lives. The old are particularly affected, for a reason. There are no absolutes, only risk factors. Somehow mother nature does not seem to favour anything but survival of the whole tree, which requires frequent and randomized pruning to be healthy. If a predator should be able to prey on our vulnerabilities that coincided with our life cycle, and that cycle was predictable, our survival would be threatened. If everyone had identical life spans, our species would have increased vulnerability. As well, cancer immunizes us against interdependence. The random interruptions of death prevent us from having to rely on each other too much, because we have to work around the possibility that another may perish at anytime. Randomized lives creates less predictability, and therefore more survivability. The randomness of cancer makes it extremely hard to nail it down, and that's exactly the idea. The randomness is based on the randomness of life itself and the universe, the ultimate random number generator. No one can predict it 100%, there are only risk factors and educated guesses.
Cancer, for the most part, is evolutionary pruning to enhance the survivability of an entire group or species, by pruning the weak branches as well as creating unpredictable lifespans and indeed lives. Cancer touches us all, they say. In fact, cancer has helped put us here.
In terms of food, there's much talk of the cancer causing effect of red meat. I asked myself why? My theory is that meat eaters need to be 'pruned' more than fish or fruit/vegetable eaters. This is because a meat-eater is a hunter of land animals, which requires more mobility that either fish or plant eating. Land animal hunters need to be young, strong, and very mobile with little baggage to be effective. Having to carry your grandmother from hunt to hunt could prove very taxing. Finding time to care for the sick or the old doesn't fit a hunter's lifestyle. We may take our mothers strawberry picking, but not lion hunting. One thing so important to the hunting or farming of animals most farmers will agree, is to understand your plant or animals life-cycle. We study behaviours of animals to be effective hunters, and they study us as well. Being unpredictable is a shield. It is a shield of random fabric partly made of cancer. A person who dies of cancer can also make great bate.
To stretch this even further, If we try to relate the increased cancer risk of fire cooking red meat, we can see that a group of carnivorous hunters that also prepare an outside fire pit takes a much bigger risk. They will be easily spotted at night, and of course the smell of a barbeque will drive other predatory animals from miles around to them, necessitating quick, organized cooking and leaving the scene of the cook very rapidly. This requires an even fitter, younger, more mobile group of hunters, requiring even more evolutionary pruning, and inevitably, a higher cancer rate.
If we look at the longest living peoples, we often see a link to foods like fish and vegetables, which basically means less mobility. Even an the elderly can catch a fish. It's not that red meat is unhealthy, but rather hunters of those foods need to fit a profile to better suit the acquisition of their diet. Pruning of the land animal hunter groups assures better survival of the entire group.
I'm convinced, and I believe the cure for cancer will be found in stages and by breeding cancer out of some fast-breeding species, we can compare the differences between the original and the evolved cell. I think also computer modeling will help us. We're the only species that understand even the existence of cancer, and we are the only ones with enough intelligence to defeat it. Cancer, however random, has met its match.
Integrated Random Biology:
Genetic variation has some predictability to it, scientists can predict certain aspects of our species by knowing the rate of genetic variation. Now the key word predict, anything predictable is vulnerable. Other species including the very big and small may use that predictability to eradicate us. When we consider how seemingly ingenious and devious life can be with even 'simple' organisms, any extra edge we may have to outsmart them by being unpredictable will help us to survive. Epigenetics allows our biology to be changed at any time in our lives, adding an extra element of survival and unpredictability.