Programmed to Change

When I was a child, I was introduced to the metamorphosis of a caterpillar to a chrysalis to a beautiful butterfly. I decided to figure out how that change took place, so I cut open a chrysalis to see what was going on inside. Instead of catching the transformation in progress all I found was a capsule of black soup. Later when I asked biologists how the process took place, I realized that no one fully understood it. The caterpillar was programmed to change, but nobody could understand how.

What I did learn was that this process goes on in a wide variety of life forms. Frogs, sea urchins, flying wasps, and beetles are just a few examples of creatures programmed to change. The December 2018 issue of National Geographic features a wonderful article about the use of 3D models and micro-CT scanning of the process. These tools have given us a great deal of understanding of how this transformation occurs. The article identifies three stages of the change that happens as the caterpillar changes into a butterfly.

1. PROGRAMMED ACTIVATION. The caterpillar eats vegetation until it is full grown. As it does so, its hormones begin to shift with some parts of the caterpillar expanding and others becoming degenerate. The thoracic legs grow into legs that are good for grasping. Four wing buds on the caterpillar’s body begin to develop into wings, and the antennae become larger. The silk gland begins to degenerate to become the chrysalis. The proleg degenerates making the caterpillar more dependent on crawling. The mandible the caterpillar uses for chewing begins to degenerate making room for a tube for sipping nectar. The simple eye of the caterpillar which could only detect the presence or absence of light begins to change. All of this is programmed into the genetic makeup of the caterpillar.

2. TRANSFORMATION. As the prolegs degenerate, thoracic legs grow to adult size. Wings develop with full color from the four wing buds. The chewing mandibles morph into two halves that zip into pipes that make a straw-like proboscis. Simple eyes move forward closer to the brain and produce a compound eye which gives true vision.

3. EMERGENCE. The brain of the butterfly is almost completely rewired to meet flight requirements.  One thing that the butterfly seems to retain from its caterpillar stage is olfactory memories. It needs that to know where to produce the next generation of caterpillars. The butterfly sucks in air until its chrysalis breaks open. The butterfly flaps its wings for several hours to dry them and to circulate blood before flying off in search of a mate.

All of this happens in 15 to 21 days. The gut of the butterfly shifts from digesting plants to nectar in that short time. There are wonderful artistic drawings of all this in the article. The author summarizes his study by saying, “..the insect’s makeover is a programmed mix of destruction and growth. Certain cells die, and body parts atrophy. Meanwhile, other cells, in place since birth, rapidly expand in as little as two weeks, the adult emerges completely remodeled, capable of flight – and bent on finding a mate.”

We would add that no programming happens by chance. It takes intelligence to program a computer. The caterpillar programmed to change to a butterfly reflects the wisdom and intelligence of a great programmer superior to anything the software companies can offer.
–John N. Clayton © 2018