There is no denying that biology is a form of chemistry. Biology is derived from and depends on all the rules of chemistry, including equilibrium, reaction kinetics, catalysis, organic synthesis, hydrolysis, entropy, etc. However, biology is a form of chemistry not seen elsewhere in the universe. Biology has emergent properties that do not allow the chemical rules we know from simple chemistry to fully (or even partially) explain the behavior of biological systems.
At first glance, the most important distinguishing feature of biological chemistry from non-biological chemistry is the degree of complexity found in living organisms. Several hundred growth factors, cyclins, kinases, molecular switches, cascade systems, recognition signals, signal transducers, receptors, and assorted other protein factors have been identified in just the related fields of transcriptional regulation and cell growth control. All of these chemical entities interact in complex concentration-dependent ways with each other and with other factors. The same is true for energy conversion, homeostasis, reproduction, and all the other functional attributes of living cells. Add a higher level of physiological complexity for multicellular organisms, and we have further emergent properties that we can see in the life all around us.
But it isn’t only the enormous degree of complexity per se that makes biology fundamentally different from the chemistry and physics from which it emerged. The distinguishing factor of biological entities is that there is no conservation law for life. Life may be created and destroyed. Living entities are formed from other living entities, and the destruction of life (defined as death) is irreversible.
The biological non-conservation principle does not violate the physical laws of conservation, because when a biological entity dies, only its biological attributes are destroyed. Matter and energy of the organism are neither created nor destroyed but are conserved or transformed as required by the laws of physics.
The physical law of energy and matter conservation can be expressed by the simple equation:
where X is the sum of energy and matter in a system, and T is time. There is no change in the total energy and matter content in the system as time goes by. Therefore X = K, a constant.
If Y is the sum of biological entities, a simple analog of the first equation is
where the rate of change in Y can be anything from negative to 0 to positive, depending on the relative values of the rates of birth (dB/dT) and death (dD/dT). The value for Y at any time can range from 0 (extinction) to C, the maximum carrying capacity of the system for life. This indicates that life is not conserved – it can be created or destroyed.
The non-conservation principle (NCP) distinguishes life from all other forms of energy and matter and leads directly to some of the important laws and attributes of biological systems. Physical and chemical rules can be used to describe the action of an enzyme or the flow of energy in a cell, but at higher levels of biological organization, physical laws are not of much use, and uniquely biological laws that take the NCP into account are required. The most important of these is evolution by natural selection, which is utterly dependent on the NCP. Without biological death, natural selection could not function. It is the requirement for death, as well as the requirement for inheritance of characteristics, that make evolution a biological construct, not directly applicable (except in very general analogies) to nonbiological systems.
Organisms die when the complex chemical interactions between hundreds to thousands of molecules no longer function in a way to maintain chemical homeostasis. The death of organisms is not equally probable, and that fact allows for natural selection to occur. Because natural selection must favor survival (by definition), biological creatures evolve with a teleonomic (Mayr’s term for programmed teleology in biology) drive toward increased fitness. Thus, creatures become better adapted to their environments, and new features arise. This is not at all proof or even indication of external design, but it is evidence for an internal design. I might mention that Daniel Dennett is a proponent of biological teleology, so the idea is clearly not theistic in and of itself.
The reductionist temptation to dismiss the existence of purely biological laws in the study of biology is a philosophical mistake that has likely been a barrier to progress in our understanding of life. Many modern biologists have rejected this view, and devoted themselves to an exciting exploration of the way complexity and emergence can lead to major insights in biological theory. I believe that a recognition of the non conservation principle in biology should be an important part of that exploration. .