Laws in Biology

In scientific jargon, law describes a true, absolute and unchanging relationship among interacting elements. Unlike in some fields, social customs and authorities do not determine the establishment of laws in science. Given that laws are derived from empirical observations, it implies that laws symbolize regularities endorsed by a majority opinion. People also use terms like rules and principles to describe consistent relationships expressed by mathematical equations e.g., Heisenberg uncertainty principle, the causality principle of physics. Here we will adopt the less demanding and the more useful definition of law as ‘a frequently observed regularity that allows for a substantial improvement of our prediction ability in well-defined systems’. The distinction among terms rule, principle, theory and hypothesis, is beyond the scope of this paper.

Our knowledge of laws, theories and hypotheses can be traced to physical sciences. While physicists have identified a number of laws related to mass, energy, momentum and so on, some of the ‘laws’ known to biologists are those of Mendelian Inheritance (Mendel 1865), metabolic scaling (Kleiber 1932) and the recent power laws (Jeong et al. 2000). However, even these laws are not absolute—they come with exceptions. For example, non-random segregation of chromosomes (White et al. 2008) and homozygous mutants parenting a normal offspring, are deviation from Mendelian Inheritance (Lolle et al. 2005). The prevailing effect of these exceptions with the overwhelming role of boundary conditions makes paradigms of scientific laws too demanding, like those based on Popper’s falsifiability concept which is of little or no use in biology (Stamos 2007).

There are fewer and fewer laws as we move from fundamental sciences, like mathematics and physics, to more complex and chaotic sciences, like chemistry, biology, and climatology.