Watching Butterfly Designs Assemble
A press release from MIT shows that great biological science
can be done without mentioning evolution
Like a carrier frequency to a radio broadcast, a story from Massachusetts Institute of Technology (MIT) hums “intelligent design” without mentioning the forbidden phrase. It illustrates that mentioning Darwin or evolution are not essential rites before doing science.
Peeking into a chrysalis, videos reveal growth of butterfly wing scales (MIT News Office). Reporter Jennifer Chu tells about new imaging techniques by MIT scientists that allowed them to watch scales forming on the wings of butterflies as they develop inside the chrysalis. “The findings could inform the design of new materials such as iridescent windows or waterproof textiles,” she writes.
With some minor surgery and a clever imaging approach, the researchers were able to watch wing scales form in specimens of Vanessa cardui, commonly known as the Painted Lady butterfly. They observed that, as a wing forms, cells on its surface line up in orderly rows as they grow. These cells quickly differentiate into alternating “cover” and “ground” scales, producing an overlapping shingle-like pattern. As they reach their full size, the scales sprout thin ridges along their length — tiny corrugated features that control the insect’s color and help it to shed rain and moisture.
The scales are so small that when we brush a butterfly’s wing we see powdery dust. Each scale is micrometers in size (millionths of a meter). The ridges that form on them are three orders of magnitude smaller than that: nanometers (billionths of a meter). And yet their placement is programmed with exquisite control as the butterfly develops. Although the article doesn’t mention this, the control of the ridges extends laterally as well, serving to create the spots, stripes and vivid colors that characterize the species.
The team found that the ridges do not form by compression. Instead, “another ridge-forming mechanism must be at work.” Understanding that mechanism is the next project. It may have practical applications, they say. Once they understand the ridge-forming mechanism that confers desirable properties on a butterfly wing, it “can help to inform the design of new functional materials.”
“This paper focuses on what’s on the surface of the butterfly wing,” McDougal notes. “But underneath the surface, we can also see cells putting down roots like carrots, and sending out connections to other roots. There’s communication underneath the surface as cells organize. And on the surface, scales are forming, along with features on the scales themselves. We can visualize all of it, which is really beautiful to see.”
What the story reveals is intelligent design along two themes: (1) the orderly placement of cells along microscopic scales, each undergoing further refinement into water-resistant structures that create structural colors (photonic crystals), and (2) biological inspiration for human design. When one hypothesis for the ridge formation didn’t fit the observations, they immediately reasoned that another mechanism must be at work. Given the visible results in the adult butterfly, the word ‘mechanism’ implies an algorithm – a programmed control system that generates a reliable outcome each time inside every Painted Lady chrysalis, billions of times for thousands of years. It’s clear that understanding how that is achieved could be useful in human engineering projects.
The research also shows that design thinking can be fun. Visualizing the growth and development of scales on a butterfly wing “is really beautiful to see,” they said. Isn’t it nice not having to drone the tone, ‘butterflies evolved the ability to make photonic crystals on their wings’ or other such ritual nonsense? Instead, the scientists can marvel at mechanisms, just like reverse-engineering an unknown technology.
Remember how it took years of work to understand the Antikythera device found on a sunken Greek ship? The researchers began with the hunch that it had a purpose, and the purpose turned out to be more marvelous than they expected. In a similar way, these scientists observed a programmed process on a nanoscopic scale as if an algorithmic process was being performed before their eyes. They watched what goes on and began thinking of ways they might imitate it. They didn’t have to say “intelligent design” or “evolution.” Just observe, describe, and apply the knowledge. Let readers come to their own conclusions about how these intricate, controlled processes came to be.
To magnify the intricacy of butterfly development, we share again this beautiful short film from Illustra Media. We also recommend the new book Animal Algorithms by Eric Cassell, which explores the amazing abilities of butterflies to perform precision navigation using the sun, stars and the earth’s magnetic field. The engineering designs that are incorporated into one butterfly stagger the imagination – all packed into an object weighing less than a paperclip.
For more videos like this, see “Awesome Wonders” at The John 10:10 Project.