Phenotypic Plasticity and Life

There are so many examples of design in God’s creation that we often overlook them. One example that has been a problem for evolutionists is the cause of the variability of traits in organisms. Scientists call it phenotypic plasticity. For example, what determines whether the sex of an offspring is male or female? Biologists tell us that it is a matter of genetics, but that isn’t always the case.

When a red-eared slider turtle deposits her eggs, the place where she lays them determines the sex of the baby turtles. If she lays her eggs in a cool place, the babies will be males. If she lays her eggs in a warm sunny spot, the baby turtles will be females. The environment where the eggs are laid controls the ratio of males to females and limits the time of year when more females will be available to produce more offspring.

Sometimes the physical shape of an animal and its diet are determined by the environment in which it finds itself. The Mexican spadefoot toad is a classic example. The tadpoles of this toad will typically feed on plankton and algae, but occasionally a tadpole will find itself in a pool that is rich in fairy shrimp. The shape and diet of the tadpole that has eaten the shrimp will change. It now becomes a carnivore with a broad head and a new shape ideal for fast swimming.

We also see this ability to change as a function of environmental conditions in some plants. For example, cabbage white butterfly caterpillars sometimes attack wild radishes. When this happens, the plant immediately begins producing chemicals in its leaves to repel the caterpillars. Trait variability is a significant issue in evolution. In Charles Darwin’s book On the Origin of Species, he spent the first two chapters trying to explain this problem, but he never succeeded.

The ability to change as the environment changes is a design feature of many life forms. Phenotypic plasticity is a testimony to the wisdom and design that God built into all life.

— John N. Clayton © 2022

Reference: American Scientist magazine, March/April 2022, pages 94-103.