The atmospheric oxygen level in Earth’s early history allowed life-forms to grow much larger than they do today. We find fossil remains of insects that grew to incredible sizes. There are wonderfully preserved fossils of a dragonfly called Meganeura which was the size of a modern-day hawk. Ants a foot (30 cm) long and centipedes that were as long as two feet (61 cm) show up in the fossil record. There are also fossils of mammals that were larger than any land mammals living today.
A major key to the huge sizes is the amount of oxygen in the atmosphere at the time those animals lived. New laboratory techniques in nuclear chemistry give us accurate methods of determining the oxygen level of the atmosphere in the past. Ice cores and tree rings confirm the measurements. Studies show that Earth’s atmosphere has had oxygen content as high as 35 percent in the past compared to 21 percent today. This higher oxygen level would have some negative consequences, with fires burning much hotter and faster and corrosion happening faster. Its effect on some living things, however, would be very positive.
Laboratory experiments have also shown us how oxygen content affects the size of living things. Insects do not breathe with lungs since oxygen diffuses into their bloodstream directly. Dr. Robert Berner at Yale has shown that a 35 percent level of oxygen in the atmosphere would increase the diffusion rate of oxygen in an insect’s bloodstream by as much as 67 percent. Body size varies directly with oxygen concentration, and experiments with fruit flies and mealworms consistently show high growth rates with increased oxygen. Studies done on alligators have shown that variations in egg development and growth are in direct proportion to the oxygen in the atmosphere. It is the same for mammals. Dr. Paul Falkowski of Rutgers has said, “Pound for pound, mammals typically need three times as much oxygen as reptiles do.” An oxygen level that would support reptiles might not support mammals.
All of this is very helpful in understanding a variety of issues relating to the Bible and the evolution/creation controversy. It is increasingly obvious that dinosaurs and humans could not survive together on this planet. At the time of the dinosaurs, the oxygen level was too low for mammals to survive. Competition for food and living space between humans and dinosaurs would be most difficult. Domestication of reptiles is impossible so humans would not be able to train dinosaurs to help with heavy chores.
The Bible does not mention dinosaurs, and no Hebrew word in Genesis 1 could legitimately be interpreted to mean dinosaurs. The emphasis that the Bible gives to the breath of living things as seen in the Hebrew word nephesh becomes more and more relevant as we learn more about how vital that concept of breath is. (See Genesis 2:7; 7:22, etc.)
Many people seem to feel that dinosaurs were unnecessary to human existence and that their presence denigrates evidence of God’s creation. The balance between the composition of the atmosphere and the abundance of life on Earth is critical. For plants to grow, there has to be soil, and soil is not as simple as it looks. Dirt must have the critical elements for food chains and cell reproduction. The production of all of those resources is not simple. As plants take in carbon dioxide and lock carbon into the soil, they release oxygen into the atmosphere. The ecological system of the planet at the time when the dinosaurs lived allowed not only the formation of soil but also the massive amounts of coal and fossil fuels we need.
We take air for granted, but what we see of the past in the laboratory and the fossil record tells us that the biblical emphasis on the “breath of life” is a special gift of God, and is not to be taken lightly.
–John N. Clayton © 2017