Unlike other woodpeckers, or virtually any other birds, acorn woodpeckers live in complex family groups numbering up to 15 adults, all of which work together to raise chicks in a single nest. This surprising discovery led scientists in the 1920s to declare that there was “communism” at play in the species. Biologist Walter Koenig, a professor emeritus at Cornell University, has been studying acorn woodpeckers at the Hastings Natural History Reservation in Carmel Valley, California for more than 40 years to better understand this complex social structure. Every summer, Koenig and his colleagues capture and band hundreds of new woodpecker chicks. Using color-coded leg bands, the researchers are able to identify and follow individual birds and their families year after year. The huge dataset they have amassed over four decades—which now includes genetic data to help the scientists better understand relatedness among individuals—has yielded surprising answers to one of evolutionary biology’s biggest questions: Why cooperate?

Depending on the season and food availability, acorn woodpeckers feed on a variety of foods, including insects, larvae and acorns. Its remarkable tongue is so long that, when it’s not in use, the tongue wraps around the entire skull and is anchored in the nasal cavity! It is perfectly adapted for probing into acorns, crevises and tree trunks. Woodpeckers have strong bills that they use for drilling and drumming on trees, and long, sticky, barbed tongues for extracting food. The bill's chisel-like tip is kept sharp by the continuous pecking action on wood.

Statements which imply that nature has goals, for example where a species is said to do something "in order to" achieve survival, appear teleological, and are typically not acceptable to evolutionary biologists. It is however usually possible to rewrite such sentences to avoid the apparent teleology. Some biology courses have incorporated exercises requiring students to rephrase such sentences so that they do not read teleologically. Nevertheless, biologists still frequently write in a way which can be read as implying teleology, even though that may not be their intention.

According to R. Isaac American Scientific Affiliation, the statement "...to keep the skin moist and pliable our ancestor developed glands and follicles..." is teleological because it implies purpose. "This is not unusual in discussions by evolutionary biologists. Walter Thorson has argued that such widespread use of teleological language (not just by biologists, but by physicists, chemists, etc.) is an indication that there is something beyond mere physics and chemistry that is going on. But it seems to me that such language is more of an anthropomorphism. We use it because we can relate to it and can understand it better, not in the sense that there really is inherent teleology. If one pins down an evolutionary biologist who uses such language, they will be quick to say that they do not mean a real purpose or intent."

The best example I can think of for behavior or an adaptation without an apparent purpose is the jumping bean moth Laspeyresia saltitans. The larva precuts an exit door in the seed capsule (carpel) months before it changes into an adult moth, a small moth without cutting mouthparts to make an exit door. In other words, the adult moth could never leave its capsule container without the precut exit door. Although an oversimplified analogy, this is like doing something as a child that is critical for your survival as an adult! To say that the larva does this so that the adult can exit the capsule implies purpose or intent and is teleological.

The construction of the exit door, often so uniformly circular that it could have been made by an electric drill, is truly fascinating. Without any cutting mouthparts how could the exit hole have been made by the adult moth? Actually, the circular escape hatch was cut the previous year by the larva, shortly after it ceased its jerking movements and before it changed into a pupa. The door is conveniently placed directly opposite one end of the cocoon. It is only partially cut through the wall of the capsule, and is easily pushed open by the emerging moth. This is sort of like pushing a small circular piece out of a scored stencil. The cutting of the exit door is remarkable when you consider that the larva has no knowledge of the purpose it will eventually serve.

The notion that evolution has a goal or purpose of intent is a widespread misconception.

Evolution’s mechanism is surprisingly simple. Those DNA variations (alleles) of a gene which give an individual a comparative advantage in terms of biological fitness – in being beneficial for successful reproduction – will automatically become more prevalent in the gene pool. Whether a given mutation leads to a fitness advantage depends on the environment of the organism in question.

We have the tendency to favor teleological ("goal-directed") explanations over causal even though with regard to nature, teleological explanations are wrong. For instance, when children are asked whether rain happens "for plants to grow" or "because water condenses in the clouds," they prefer the first explanation.

The evolutionary biologist Richard Dawkins (1986) used the analogy of a “blind watchmaker” to describe natural selection: "blind" because it is a mechanical process lacking any sort of foresight, and "watchmaker" because nonetheless, it manages to produce structures (living organisms!) that look as though they were deliberately designed.

Evolution has no purpose; it simply happens. There is no reason to assume that evolution comes with some objective "improvement". The only thing that is constantly improving is the adaptedness of individuals to their given environment. Because the environment changes, this "progress" always remains relative – progress relative to the adaptedness to an environment.