Eating to excess studied

I don't know anyone, fat or thin, who doesn't indulge on holidays. I suppose there are some obsessed people who follow their ritually perfect diets every day of the year but most people relax their dietary restrictions during "the holidays" (funny, isn't it that we all know what "the holidays" means...the time between Thanksgiving and January 1). A researcher at University of AZ, Dr. Bradley Appelhans, has studied why people indulge in excess eating in general. According to Dr. Appelhans, we are hunter-gatherers by biology so we are storing up fat to endure the lean times to come (and I don't think he means the economy).
I kinda don't agree with him. I think our species (and I'm referring more to those who reside in big cities) is pretty far removed from the hunter-gatherer biological construct. I'm not going to fight with him over our ancestry but we've had enough centuries for genetic mutations to have perhaps made some change to that issue. I think that's an "excuse". How does that explain the burgeoning issue of obesity around the world if eating excess calories is part of our genetics? Researchers are always showing statistics that reveal how we have steadily gotten heavier through the years. If eating excess calories has always been part of our genetics, why are we getting fatter now?
I don't buy his reasoning at all. I think that's why we "hold onto" the calories but that doesn't explain why we eat excess calories in the face of abundance.
The conundrum is not solved by Appelhans's research--at least not to my satisfaction. I shall keep searching.
Is it because there are more calories available to us now? More calories to store up?
Pardon me while I store up fat for the winter.