Do We Forage for Food? The Similarities Between Mice, Rats, and Humans

    Have you ever been looking out your window into a yard or park and noticed the animal life- say, rabbits, squirrels, or birds- and thought to yourself, "how do they find enough food to survive?" This may lead to a train of thought that brings you back to how the earliest human ancestors survived as hunter-gatherers. In today's world, it seems completely far-fetched to believe that anyone can hunt or gather enough nutrition to keep a family healthy without burning too many calories. Have you even wondered how long you would survive in a pre-agricultural revolution age? Well, in terms of foraging behaviors, humans and smaller mammals (like mice and rats) aren't too different. According to the study "Sensitivity to "Sunk Costs" in Mice, Rats, and Humans", by Sweis et al., humans, mice, and rats exhibit. rather similar results in terms of weighing the costs and benefits of choosing between forage-able goods. That is to say, the foraging behaviors that have been naturally selected for over time in smaller mammals are also present in beings with higher cognitive abilities, like humans. Given that we often use a form of these reasoning skills on a daily basis, it seems incredible that the same strategies are being utilized by a variety of animals.

    So, what do these foraging strategies look like for rodents? In the Sweis experiment, the mice and rats. were placed in a "maze" that acted similarly to a food court. After training, they knew what kind of food to expect in each zone, and a tone indicated how long they would have to wait to collect that food. Since the rodents knew that they has a certain time limit in the maze that would provide their full calorie count for the day, they had to alter their foraging behavior to weigh the costs and benefits of waiting for each food. The recorded behaviors indicate that mice and rats are susceptible to the "sunk cost fallacy", which means that irretrievable resources (i.e., time and energy) that have already been spent are factored into present behaviors. For example, if a mouse knows that it has spent too long waiting for a mediocre reward, it might have a lower tolerance for future long-wait times.

    Humans experience this "susceptibility to the sunk costs" when we feel regret about a decision. Regret shapes our future decisions, because we know that we should not make the same choice, based on our past observation that said decision wasn't worth the cost. However, we can feel regret about a variety of life experiences, and since most people are not relying on foraging to survive, how do we know that these behaviors are translatable? The Sweis experiment showed comparable patterns in people who went through a similar "food court" trial, but these investment strategies are skills that we use on a daily basis and have been practicing our whole lives, so it's fair to be skeptical in the claim that we have innate foraging capabilities. Without our reliance on high cognition for problem solving, would we still see universal foraging behaviors?

    An article from Scientific American, "Our Brain is Better at Remembering Where to Find Brownies Than Cherry Tomatoes", details another experiment involving the "foraging" behaviors of people in regards to our food. One of our defining traits as humans is an incredible memory storage, which has been an enormous evolutionary advantage. Memory has enabled, for example, our abilities to learn language and tool use, two defining hallmarks of. our success as a species. Some residual memory talents left over from our hunter-gatherer days, according to the study detailed in the article, involve having better spatial memory (i.e., recalling where things are) for higher calorie foods than for lower calorie foods. In the experiment, people were almost 30% more accurate at remembering the location of the high calorie versus low calorie foods. This is especially incredible considering that when the subjects ranked how they liked the taste of foods in the experiment, there was no correlation between liking the food and remembering where it was located, but there was a correlation between spatial recall and the number of calories. So, even for someone who hated chocolate, they are still more likely. to remember where the brownies were compared to the cherry tomatoes. 

    This skill would have been useful for our ancestors when they were foraging, since being able to remember where the most nutritious food was located may have saved them from starving in harsh seasons. And we still have this skill today! Even though our society may have eliminated the human need for hunter-gatherer competence, our foraging skills remain and are being used every day. These hidden talents prove our similarity to other animals, and are a testament of the incredible precision of evolution. 

https://www.scientificamerican.com/article/our-brain-is-better-at-remembering-where-to-find-brownies-than-cherry-tomatoes/

Sweis BM, Abram SV, Schmidt BJ, Seeland KD, MacDonald AW 3rd, Thomas MJ, Redish AD. Sensitivity to "sunk costs" in mice, rats, and humans. Science. 2018 Jul 13;361(6398):178-181. doi: 10.1126/science.aar8644.