Studies of non-human primates, rats, black-capped chickadees, scrub-jays, and tayras indicate that animals may have a sense of "the future," and act accordingly.

Mental time travel is the ability to remember past experiences and anticipate future ones. While this ability is obviously found in humans, scientists are less clear about whether or not they believe it is found in animals. However, the results of several studies support the hypothesis that animals do have a conception of the future and are able to perform mental time travel in similar ways to humans. This literature review discusses several such studies and their implications.

The authors of the review go over several types of studies and present multiple examples of each type. One type of study observes how animals modify how much they eat of one type of food when they know that a different type of food will be available at a future time. For example, in one 2011 experiment, chickadees in the experimental group were offered sunflower seeds and then were later offered mealworms, whereas chickadees in the control group were only offered sunflower seeds. Chickadees prefer eating mealworms to sunflower seeds, though they like both. After several days of this pattern, the chickadees in the experimental group ate significantly fewer of the sunflower seeds offered to them, preferring to save their appetites for the mealworms that they knew would soon follow instead. This intentional suppression of appetite on the part of the chickadees was observed even when there was a half hour delay between being offered sunflower seed and being offered mealworms. The authors note that this behavior is akin to humans eating less of the main course to save room for dessert.

Another type of study discussed in this review is one which observes how animals choose between options that lead to different future outcomes (one option leads to a small reward received immediately whereas the other option leads to a larger reward received at a later time). In one example, a 2004 experiment on squirrel monkeys found that they were willing to choose fewer peanuts initially if it meant that they would be rewarded with more peanuts later.

A third type of study discussed involves animals who move food from one place to another. A 2011 study observed that Tayras (a type of weasel) in Costa Rica would eat ripe plantains immediately but would store unripe plantains in trees and come back to eat them later when they were ripe. This shows that the Tayras were aware that at some future time, the plantains would become ripe enough to eat.

Finally, the authors discuss studies where animals are observed to plan with tools. For example, a chimpanzee from a zoo in Sweden was continually observed storing stones to throw at human visitors later in the day when the humans came by. The chimpanzee only used the stones for this purpose, and did not store them during the off-season while the zoo was closed to visitors. These details imply that the chimpanzee was using foresight and planning for a specific future event (visitors coming by) when storing those stones. It also seems to imply that the chimpanzee was unhappy with his captivity.

Some have tried to discredit the findings of the studies discussed in the review, by saying that the animals may have only been using associative learning rather than having a genuine understanding of the future, or by attributing the animals’ behaviors to other forms of cognition separate from cognition of the future. However, the authors believe that the explanation that makes the most sense and is the simplest, is that future cognition and mental time travel abilities really are present in the animals studied. The authors suggest that future studies could try to answer the questions of whether animals can form several alternative plans for the future to choose from, and whether animals understand that different future events will take place at different points in time in relation to one another. Additionally, future studies may explore if/how evolution plays a role in the extent to which different species can practice mental time travel and cognize the future.

For present day advocates, this review provides compelling evidence that animals do have a sense of the future, which may provide a stronger case for their being deserving of certain welfare standards and rights. Studying this phenomenon without keeping animals in captivity would no doubt compel more animal advocates to support such research.