Oak Hill Memorial Park

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Oak Hill Memorial Park, Escondido
  Acorn Woodpeckers, Teleology & Ants

© W.P. Armstrong 18 May 2021

Acorn Woodpecker & Teleology

This massive Aleppo pine (Pinus halepensis) in Escondido's Oak Hill Memorial Park is a favorite place for storing acorns. The acorn woodpecker is genetically adapted to stuff acorns into the bark of trees. This acorn "granary tree" provides a food source during the winter months. Some people believe this remarkable behavior also has a teleological (goal-directed) explanation based on purpose. In the wild through natural selection, stuffing acorns was an advantageous heritable adaptation because it prevented other animals from eating them (and it allowed them to dry out). Of course, this behavior also requires a sharp, chisel-like bill and well-cushioned brain. The acorn holes usually start a few feet up the tree trunks, which makes it easier for the woodpeckers to defend their acorns from deer, squirrels and jays.

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.

Note: According to American Insects by R.H. Arnett (1985), the jumping bean moth belongs to the Order Lepidoptera, Family Tortricidae, and is listed under the scientific name of Cydia saltitans. It is listed as Cydia deshaisiana in Volume 3 of Nomina Insecta Nearctica (1996) and more recent publications in entomology. The scientific name Laspeyresia saltitans is a synonym used in most older entomology references. This moth species inhabits the carpels of Sebastiana pavoniana and apparently also Sapium biloculare (Sebastiana bilocularis), native shrubs in Mexico and Arizona.

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.

CRISPR (an acronym for Clustered Regularly Interspaced Short Palindromic Repeats) is a family of DNA sequences found in the genomes of prokaryotic organisms such as bacteria and archaea. These sequences are derived from DNA fragments of bacteriophage viruses that had previously infected the prokaryote. They are used to detect and destroy DNA from similar bacteriophages during subsequent infections. Hence these sequences play a key role in the antiviral (i.e. anti-phage) defense system of prokaryotes such as bacteria and provide a form of acquired immunity. Palindromic repeats provide acquired, yet heritable, sequence-specific 'adaptive' immunity against phage viruses. Implying teleological "purpose" or "goal" are not appropriate scientific terms when describing acquired immunity to viruses. It just turns out that certain palindromic sequences derived from viral DNA destroy invading viruses and happen to be a good genetic adaptation for survival. The following is a simplified explanation of palindromic.

Palindrome is a word, verse, or sentence (such as my granddaughter's name HANNAH) that reads the same backward or forward. A palindromic DNA sequence is a sequence made up of nucleic acids within double helix of DNA that is the same when read from 5' to 3' on one strand and 5' to 3' on the other, complementary, strand. An example of a palindromic sequence is 5'-GGATCC-3', which has a complementary strand, 3'-CCTAGG-5'.

Another Simplified Explanation Of Palindromic Name & Palindromic DNA Sequence

In some species of figs (Ficus) the symbiotic fig wasps passively exit the fig syconium through a mass of pollen-bearing male flowers. In other species the wasps are genetically adapted (DNA programmed) to deliberately fill their pollen baskets (corbiculae) before exiting the syconium. The latter term is referred to as "purposive" which is probably not the best adjective because it implies purpose or goal. The wasps have a genetic adaptation to fill their pollen baskets, like the jumping bean moth larva is adapted to cut an exit door. A genetic adaptation is defined as a biological characteristic with a heritable basis that improves reproduction and/or survival and results from evolution by natural selection.

Exerpts From "Why Evolution Has No Goal" by Lukas Gloor.
Crucial Considerations Blog (Accessed 20 May 2021).

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.

  Why Evolution Has No Goal  

Myrmicinae: Little Black Ant (Monomorium minimum)

I originally thought this ant image by Steven Disparti might be a species of Temnothorax; however, it was verified as Monomorium by myrmecologist Gordon Snelling (Personal Communication, 18 May 2021). It also keys out to Monomorium in the on-line "Key To California Ant Genera" by Phil Ward, Univ. of Calif., Davis. In the on-line "AntWiki Key To U.S. Monomorium Species" it keys to M. minimum based on "dorsal face of propodeum longer than posterior face. In addition, it matches M. minimum that I photographed at Walnut Grove Park in Twin Oaks Valley, San Marcos, CA.

Other ant species in this lovely memorial park include the Argentine ant (Linepithema humile) and rover ant (Brachymyrmex patagonicus). There are undoubtedy many more species. With all the oaks and pines it would appear to be a possible habitat for Temnothorax. I photographed T. andrei near coast live oaks (Quercus agrifolia) at nearby Daley Ranch.

  Macrophotography Techniques By W.P. Armstrong  

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