SCIENCE: MYOPIC RESEARCH

EYE-LINES OF FISH AND BIRDS

Myopic research is used here to refer to faulty research that omits consideration of important factors that give a different answer than the one given by the researchers.  There are many ways by which such failings can be generated.  The research criticized here [Ficken, R. W., P. E. Matthiae, and R. Horwich.  1971.  Eye marks in vertebrates: aids to vision.  Science, 173:936-939.]  happens to involve vision of birds and the evolutionary cause of eye-lines of certain birds.

 Their research showed a correlation of eye-lines of certain shore birds with feeding on small mobile prey.  Because the eye-line narrowed from a wide base immediately in front of the eye to a sharp point aimed directly at the tip of the beak, they concluded it was an aide to vision, functioning as an aiming stripe.

I had researched the literature on concealing coloration during the late 1950's when trying to understand a dramatic color pattern of a reef fish. [Engemann, Joseph G.  1960.  The effect of coloration on Great Barrier Reef animals.  Pap. Mich. Acad. Sci., Arts, and Letters, 45:9-15.]  I knew that eye-lines are often an integral part of a stripe along the body of many snakes that makes the eye less obvious when it moves.  I also had seen many coral reef fishes that had eye-lines perpendicular to a line drawn from eye to mouth as in several of the fish from Heron Island, Great Barrier Reef, Australia as illustrated below.

The fourth one down in the middle column shows how the eye can not easily be distinguished when it is part of a dark line.  The dark spot on the tail of the fish below the referenced eye-line is called an ocellus since it mimics an eye and deceives predators that try to aim at or in front of the head so they will catch the fish if it darts away.  The three in the upper left also have the ocellus on the tail as well as a vertical eye-line.  The vertical eye-lines make them blend in with their background when stag-horn corals are present.

After reading the research report of Ficken et al., I did a follow-up study of bird eye-lines and found that the passerine birds that were insect eaters usually had eye-lines, much more so than seed eaters.  It seemed apparent that the insects were more likely to provide food to the bird if they could not see the dark eye approaching as easily.  Thus the selective force was not so much a vision aid as a concealment aid.

COMPREHENSIVE VIEW NEEDED FOR RESEARCH

Multiple causes can interact in the selective force directing evolution of biological features.  Multiple causes should be considered by researchers in all fields when it is appropriate.

REDUCING MYOPIC RESEARCH

Broad experience is helpful in making one check all the angles pertaining to a research project.  The focused research utilizing computerized internet searches should be supplemented with broader reading in varied research fields.  Cross-application of concepts is more apt to result from such an approach.  Preparation in graduate training should not be limited to the research project as many of my peers were wont to do when they avoided seminars on other topics.

The evolutionary concept of natural selection and/or survival of the fittest has broad application potential beyond biology.  Evolutionary change is likely to produce a more successful society than revolutionary change,  Can that occur if extreme views are contesting for control?

Joseph G. Engemann        July 31, 2014