It's important that we, as a species, try out new diets. We are naturally learning what keeps us alive longer. Technology, medicine, diets, research into cellular apoptosis, cancer research, food sources.
We have completely eliminated the sicknesses associated with eating uncooked meat. Any young child will immediately get taught the value of cooking food through daily actions dealing with uncooked meat. As that child grows up, some fear will be instilled by social health warnings in restaurant menus.
Nobody would ever allow any other human, to eat uncooked chicken. The cleanliness required for beef tartar is well-known. And whenever somebody orders it, the discussion following the questions regarding eating uncooked beef and the level of cleanliness required, is an evolutionary response to uncooked meat.
Whenever we notice a certain subset of humans living longer (e.g. the Inuits), we study their diet (e.g. high in nut fats) and their health statistics (fewer percentage have heart disease). Our curiosity and our fear of death immediately get piqued.
We send sociology studies off into what sort of communal setting lowers the risk of heart disease because we are curious if they've figured out some trick. Something to delay our impending sense of mortality and death. We pour millions of dollars into cancer research and healthcare debates. Because we, as a species, need to decide the best way to stay alive and remove our fear of death/extinction.
That's why fad diets are so important. We need new random people trying out different diets, some succeeding in health, and some failing in health. We need to keep trying different things, and we need fads and viral information. That's why we need yogis from the East to try relaxation techniques into keeping a healthy metabolism and teach it to the Westerners, and why we start to study it with MRI machines in the West.
Because we, as a species, are joining together to figure out how to defeat death and extinction.
We might get to a point where people eating raw sugar are immediately swatted away, the same way that people eating uncooked meat are disuaded.
With uncooked meat, we've overcome the random percentage that bacterial infections from uncooked chicken would affect the species. If uncooked meat would have a 50% chance of death by 3 years old, it would have been eradicated quickly in the evolutionary series (which is why we've eliminated that before other diseases). Once our average age of death ("life expectancy") is 110 years old, we may find, through research into cellular aging, that sugar makes one have a 50% chance to die by 115. Eventually, for the average age of death to be 140 years old, one may have had to eliminate raw sugar in the diets of everybody .
This isn't about raw sugar, because I have no idea if that will stop us from living longer. But for us to overcome our fear of death, and pushing our average ages up well past 100, there will have been things we socially condition into our species from an early age.
A species who has learned, through many generations of trial and error, to live to 1000, expand to other planets, and work together, will eat raw sugar like our current society eats raw meat. Dying by 10% of our potential life expectancy would be a child in the eyes of an elder of this hypothetical society.
Our fear of death makes us greedy as a species and also makes us divert resources and attention into endeavors which allow us to survive longer. If we don't kill ourselves off before then, we'll be able to experience these incredible feats of evolution or learning.
As an aside, I call this form of abstract thinking "Evolutionary Thinking".