by Dr Carl Wieland and Dr Jonathan D Sarfati

Most modern creation organisations, CMI among them, are aware of the substantial problems, both biblical and scientific, with the ‘pre-Flood vapour canopy’ model.1

One argument used to support that notion was the contention that atmospheric oxygen partial pressurehad to be higher in the past, in order for giant insects to have been able to breathe. (The weight of the canopy, by increasing total pressure, would have increased oxygen partial pressure.)

The idea was that since insects had no lungs, but breathed passively through tubes (tracheae) leading to holes on the outside (spiracles), this limited the size they could reach. Thus, the existence of some very large insects in the fossil record was support for the idea that oxygen partial pressure was higher.

Big bugs

For example, Megaloprepus caerulatus (figure 1), the largest dragonfly species today, has a wingspan of up to 19 cm and its body is over 12 cm long. By contrast, the extinct Meganeura dragonfly found in the fossil record had a wingspan of nearly 90 cm, and its body was up to a metre long.

However, this seemed to crumble when it was discovered that insects don’t breathe passively at all,3 but “pump their air tubes much as humans expand and contract their lungs.”4  This means that a key argument that increased oxygen partial pressure was necessary for large insects is shown to be unsound.

But in an interesting twist, researchers have now shown that raising insects in high levels of oxygen affects their size, though very unevenly.5….

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