McDonald’s burgers have been making the news quite a bit lately – and for the most part, it is not because of their taste.

Instead, the internet has seen an influx of photos and stories focused on how McDonald’s burgers have defied logic and managed to go years without rotting.

In an attempt to dissuade people from eating fast food, for example, a chiropractor in Nebraska displayed a 2-year-old McDonald’s Happy Meal in his office. Opposing Views ran a story on his experience. Here is what they looked like when they were older than some people's children:

Another man, David Whipple, reportedly saved a McDonald’s burger for a whopping 14 years, at the end of which the burger still had not rotted.

Whipple has said that he saved the “artifact” to show his grandchildren just how packed with preservatives and chemicals fast food is.

McDonald’s Canada, however, has now spoken out and offered a different explanation to the mysterious question of why these burgers do not rot.

“There have been a lot of online videos and photos touting the fact that when left out for an extended period of time, a McDonald’s hamburger does not rot and that this is because they are laden with chemicals,” said Dr. Keith Warriner, the program director at the University of Guelph’s Department of Food Science and Quality Assurance.

“The reality,” continued Warriner, “is that McDonald’s hamburgers, French fries and chicken are like all foods, and do rot if kept under certain circumstances.”

Warriner explained that the burgers’ resistance to rotting can be traced back to the fact that McDonald’s patties and burgers have been stripped of much of their moisture. And moisture, along with nutrients, warmth and time, are what enable microbes to grow and cause rotting in food.

Thus, if moisture or another of these elements is removed from food, microbes are not able to grow in the food and spoil it.

A McDonald’s patty loses water when it is cooked; the bun loses moisture when it is toasted. So, after preparation, the hamburger is already fairly dry. And, because the humidity in most buildings is around 40%, if the already-dry hamburger is left out in a room, it will simply continue to lose moisture instead of rotting.

As the food blog A Hamburger Today demonstrated, this phenomenon is not unique to McDonald’s hamburgers. The AHT bloggers ran a series of experiments on home-ground burgers and McDonald’s burgers which proved that when exposed to the same factors, neither type of patty rotted.

AHT noted that although the samples “had shrunk a bit…they showed no signs of decomposition.”

Sources: Business Insider, CNBC

Photo Sources: Business Insider, Smart Planet