Sweaters for Squirrels

I got a call from a lady who was making sweaters for squirrels. She was concerned that the cold weather would make the squirrels shiver and get sick if they didn’t have protection. I tried to tell her that her heart was in the right place, but God had already made wonderful coats for the squirrels. Because of that, they do not require winter clothing to add to what God had already given them. That led to a discussion of birds who didn’t have fur coats. I asked her if she knew about goose down, and she admitted she had a goose down winter coat. “But those poor little birds on my feeder don’t have down,” she replied, “and I have seen them shiver.” Sweaters for birds seem to be more problematic than sweaters for squirrels.

That exchange started me thinking about the many ways God has equipped living things for cold climates like the one here in Michigan. When I taught physics in the public high schools of South Bend, Indiana, we covered conduction, convection, and radiation. I began the discussion on conduction by asking why we wear clothes, outside of the obvious one. The thermal conductivity of various kinds of clothing helps us stay warm in winter and cool in summer. For example, goose down is a good insulator because it holds pockets of air, and air does not conduct heat well. Likewise, the design of skin and hair involves thermal conductivity, which is why being immersed in cold water takes heat out of our bodies rapidly, causing hypothermia.

Fat is another insulating material, and having very little fat in one’s body can cause rapid heat loss. Even the color of one’s skin or hair can make a difference. One of the experiments that I had my students do was to take two identical cans and paint one black and the other white. We would then put boiling water in each can and measure the temperature of the can every minute, graphing the cooling curve of the two cans. The black can would cool much faster than the white can; in this case, the cooling is by radiation, another heat transfer method. We all know that black objects absorb heat from sunlight better than white objects. Therefore, black things also release heat more rapidly.

The physics of heat transfer is another design feature built into living things. All animals are designed with the right equipment to survive in their natural environment. That is why we don’t need to make sweaters for squirrels. However, when humans move animals to a radically different climate, the result can be dangerous.

Climate change is causing some animals to migrate to latitudes where their survival is not threatened. That is also a design feature of life. In Job 39, God challenges Job with questions about design features in living things. We are only now beginning to understand the answers to some of those questions.

— John N. Clayton © 2022