Squirrel adaptations to their environment not only promote their own survival and multiplication, but also contribute to other organisms and the ecosystem. Unable to digest cellulose, they tend to select foods rich in protein, carbohydrates, and fat, and eat such plant food as nuts, seeds, fruits, as well as fungi, insects, eggs, small birds, small mammals, frogs, and so forth. In consuming the nuts, seeds, and fruits, they help in disbursing the plants. In particular, their unique adaptation of hoarding the food, by gathering and burying nuts and seeds, fosters the development of the forest, which regenerates from uneaten nuts and seeds. They also help to keep insects under control. Furthermore, as a taxa, they are integral to food chains, serving as a food source for various birds, such as owls.
These activities mentioned above represent a unity of the individual purpose of squirrels (survial, reproduction, maintenance) and a purpose for the whole (for other organisms and for the ecosystem).
Unification thought recognizes a more fundamental purpose for the whole relative to the role of squirrels for humans. For people, squirrels serve numerous purposes. They are collected for meat and fur, and provide aesthetic pleasure, adding to the human delight in nature. People enjoy the company of tree squirrels and chipmunks and like watching their seemingly cheerful and energetic antics, and enjoy watching flying squirrels glide or the sight of a groundhog. Squirrels are also featured in books and artwork.
However, squirrels can also be pests, eating crops and causing electrical outages. Human creativity, which developed monoculture and widespread electrical power, is devising means to limit the destructive interactions with squirrels.