The remarkable entomologist Charles Henry Turner
When people think about scientists, especially those who have made major accomplishments in their fields, they subconsciously assume those people had tremendous academic credentials. They must, it is often assumed, have worked and performed research in higher institutions of learning. Charles Turner is an exception and has quietly made significant contributions to behavioral studies of insects and spiders.
Born in Cincinnati, Ohio, USA on February 3, 1867, barely two years after the U.S. Civil War, Charles Turner was encouraged by his parents (a church custodian and nurse) to read and learn. But he also collected and catalogues many insects, because book learning alone was not enough. He graduated at the top of his high school class in 1886. A year later, Turner was accepted at the University of Cinncinati, where he obtained a bachelor's degree in biology in 1891. He studied under Clarence Herrick, who had gotten his master's degree shortly beforehand in 1885. Herrick was the chair of biology at the University of Cinncinati and founded the Journal of Comparative Neurology.
Herrick was interested in neurology of brains of all vertebrates but thought the key was in the lower species. That probably focused Charles Turner to compare the structure of brains of birds to reptiles and humans for his >100-page undergraduate thesis in 1891. He published part of it in his advisor's journal. His thesis work demonstrated skills in dissection, histology, observation, drawing, and analysis which became his hallmark. He even developed a new dissecting tool (felt-tipped pliers) for handling delicate and slippery tissue. By accident, he also improve a tissue staining technique and was honest enough to say so in the paper:
An accident led to the discovery that the substitution of aluminium sulphate for the alum called for in the formula of Czokor’s alum cochineal is a vast improvement. The stain not only becomes more selective, acting almost solely upon the nuclei, but it is more prompt and reliable and the color resulting is more pronounced and agreeable. (Journal of Comparative Neurology, 1, p. 134, 1891)
Turner even suggested that the compact nature of birds' brains in their skulls might be used in taxonomy to categorize them.
A year later, he published more of the work (A Few Characteristics of the Avian Brain), though barely a page long, in the prestigious journal Science as the first article by an African American. Turner continued to study under Herrick to obtain his master of science degree in 1892. That same year, he also published on the behavior of spiders to create webs. He noted that "an instinctive impulse prompts gallery spiders to weave...webs, but the details of the construction are the products of intelligent action". This he determined after providing spiders with circular or square environments to build webs matching those shapes, and then showed how they used ingenious methods to repair damage to them.
In 1892, the 24-year-old Turner also published a note (again in Science) about a grape vine producing two sets of leaves during the same season. And, in the same year, he published on new species of aquatic invertebrates. From 1892 to 1893, he was assistant instructor in the lab while Herrick took leave to study in Leipzig, and on his return he found he was in poor health and had to move to New Mexico to recover. But Herrick's enthusiasm for research had rubbed off on Turner.
Turner's success in Cinncinati included lively weekly lab meetings free from racial discrimination, which marked him as an "indefatigable worker", as his publication record showed. But after his master's degree, Turner ran into problems finding long-term work for 15 years. Sadly, he was not accepted at the all-Black Tuskegee Institute (1893) where George Washington Carver worked due to its lack of funds. Thereafter, he worked short stints as a professor at Clark University (1893–1905), a high school principal at College Hill High School (1906), a professor at Haynes Normal and Industrial Institute (1907). Finally, in 1908 he became a teacher at Sumner High School in St. Louis.
Despite moving around like that, he published 21 more scientific papers plus a book on invertebrates. While working at Clark University, he began a Ph.D. at Denison University (1893-1894) but had to quit when the program was discontinued. It wasn't until summer of 1906 when he started again, this time at the University of Chicago and finished in 1907 graduating magna cum laude with a doctoral degree in zoology, one of the first awarded to Blacks there. His doctoral dissertation was titled "The Homing of Ants. An Experimental Study of Ant Behavior". Ahead of his time, he wrote: "Ants are much more than mere reflext machines; they are self-acting creatures guided by memories of past individual ...experience."
- In 1907, he observed ants guarding and defending entrances to glass chambers in interconnected artificial Janet boxes, and enclosing a nest chamber with available debris. Because only a few ants at a time would repair the debris barrier, Turner felt they made conscious decisions who would do the work.
- He also trained them to take advantage of his own help. When an ant fell off a platform in his experiment, he would use either a forceps or lab spatula to bring them back to the point where they had fallen. After doing this a few times, ants would purposefully approach either tool when it got close.
- He also found they could build partial bridges across water with paper and bread crumbs, with a clear goal in mind.
- He showed they didn't return to their nests after foraging simply by intuition. They learned in their exploration with various cues. French scientist Victor Cornetz called the loops “Tournoiements de Turner” (Turner circling).
- In 1908, he observed how male and female Melissodes bees court in flight.
- When other scientists felt that bees navigate using wind and the sun, In 1908, Turner proved that instead they use landmarks. He observed how mud-dauber wasps entered a room to seek out a nest (item a in the picture below). Then, after manipulating the shades to adjust the source and amount of light in 17 patterns, he concluded: "This series of experiments warrants the induction that, in the wasp's memory, that nest is located in a certain direction and at about a definite distance from a bright patch which is situated at a known elevation in a peculiar environment."
- His work on recogizing landmarks was not confined to the indoors. Turner was also known for the earliest studies on how bees see color and patterns in flowers. These are important factors to help them find pollen. About 14 km (8.5 miles) NE of Sumner High School was O'Fallon Park, where Turner used an abandoned garden to study bees. He recorded changes in their flight patterns to and from their burrow nests after he changed major landmarks, and he concluded these caused them to search in the wrong place for home. “By a process of elimination, the most consistent explanation of the above behavior is the assumption that burrowing bees utilize memory in finding the way home, and that they examine carefully the neighborhood of the nest for the purpose of forming pictures of the topographical environment of the burrow.” Twenty and seventy-five years later, others would repeat his work not knowing what he had already found.
- From 1838 to 1910, a few researchers thought that bees could see in color, but nobody could show any actual evidence. Karl von Frisch won the Nobel Prize for his 1914 work on honeybee dance behavior, but he was 4 years too late to be first to work on color vision. von Frisch also showed that bees use a sense of smell to find and choose flowers. Turner conducted 32 experiments in a week with cardboard discs, cones, and boxes of different shapes all baited with honey. Not knowing that bees can't see red, his work with red, blue, and green traps was flawed, but his data still demonstrated visual and olfactory cues were used in the bees' behavior: “whether this is a true color vision or simply a greyness discrimination is no easy question to answer.”
- His work with bees also showed that they could distinguish patterns on the honey traps, and they could learn when Turner had changed the source of honey from one trap to another.
- In 1912, he improved on another researcher's test to examine cockroaches' memories. He would shock them in one dark box and noticed they wouldn't reenter it, even with prodding. To confirm that it involved memory of that specific location, he moved the cockroaches to a new box, and it immediately ran into the dark section. So, it remembered something about the first box and avoided its shock penalty.
- In another experiment, he taught cockroaches to run a maze of copper strips suspended over water (punishment if they fell off). Turner observed how they would examine their previous path until they figured out how to reach the goal down a ramp.
- He confirmed that moths respond like Pavlov's dogs to the specific sound of a whistle. Their container was shaken at the same time as the whistle tweet, and their wings moved as if they were preparing to escape. After learning this, they fluttered their wings just to the sound without any rough shaking. Pavlov wouldn't publish his own similar work and theory for 14 more years.
Charles Turner died on Valentines's Day in 1923 of acute myocarditis at 56 only one year after retiring from Sumner High School. Some say it was due to his immense workload and determination to perform research despite the harsh conditions. The epitaph on his tombstone in Lincoln Cemetery in Chicago reads only “Scientist.” It is quite an understatement.
Here is a six-minute video showing Turner's influence today on youths and modern science.
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