February 20th, 2013
Birds' Breathtaking System
In a previous issue of Think & Believe (Vol.2, No. 5), we discussed the unique features relating to flight in birds, including positioning and control of feathers, size and structure of bones, and efficiency of the circulatory and digestive systems. In this article we consider the amazing respiratory system, which, according to Dr. Michael Denton “seem(s) to defy plausible evolutionary explanations.” (Evolution: A Theory in Crisis, p. 210)
Most vertebrates draw air into their lungs through a series of branching tubes which finally terminate in tiny air sacs. The air must enter and exit through the same tubes, leaving a certain amount of residual (“dead”) air in the lungs.
Birds have a totally different system, though. Special air sacs extend from the lungs into all major parts of the bird’s body. They do not function directly in gaseous exchange, but serve as “bellows” to maintain a constant flow through tiny air tubes where the exchange actually takes place. These tiny air tubes branch profusely, permeating the lungs, and then join together again. Special valves in the tubes ensure that air flows in only one direction through the lungs, providing the continual supply of fresh air needed for flight.
This is a very amazing system, which poses a serious challenge to evolution. According to Denton:
No lung in any other vertebrate species is known which in any way approaches the avian (bird) system. Moreover, it is identical in all essential details in birds as diverse as humming birds, ostriches and hawks.
Just how such an utterly different respiratory system could have evolved gradually from the standard vertebrate design is fantastically difficult to envisage, especially bearing in mind that the maintenance of respiratory function is absolutely vital to the life of an organism to the extent that the slightest malfunction leads to death within minutes. Just as the feathers cannot function as an organ of flight until the hooks and barbules are co-adapted to fit together perfectly, so the avian lung cannot function as an organ of respiration until the parabronchial system which permeates it and the air sac system which guarantees the parabronchi their air supply are both highly developed and able to function together in a perfectly integrated manner.
...The suspicion inevitably arises that perhaps no functional intermediate exists between the dead-end and continuous through-put types of lung. (Evolution: A Theory in Crisis, pp. 211, 212)
Suspicion indeed! This fantastically complex system defies evolutionary explanations and proclaims the wisdom and power of the ALMIGHTY CREATOR GOD!
By Dave and Mary Jo Nutting
Originally published in the March/April 1995 Think and Believe newsletter.
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