SCALE-INVARIANT CORRELATIONS IN THE BIOLOGICAL AND SOCIAL-SCIENCES

In this opening introductory paper, we discuss the possibility that sc ale-invariant correlations may be a feature of biological and possibly even social systems. We illustrate this possibility by reviewing rece nt work at Boston University. Specifically, we focus first on the appa rent scale-invariant correlations in non-coding deoxyribonucleic acid (DNA) and show that this feature can be used to distinguish coding and non-coding DNA. We argue that the inflating a degassed lung is charac terized by a cascade of avalanches, as the airways successively open, and that distribution functions characterizing this cascade are scale invariant. Moving from the lung to the heart, we find that the sequenc e of interbeat intervals is characterized by scale-invariant correlati ons in health, but not in disease. Moving from individual organs to en tire organisms, we discuss recent experimental evidence that the forag ing behaviour of the wandering albatross is governed by a scale-invari ant Levy distribution. Finally, we enquire whether scale invariance de scribes not only animal behaviour but also human behaviour. To this en d, we analyse data on urban growth patterns, on finance and on economi cs. For all cases, we find empirical evidence of scaling behaviour. We conclude by asking why such complex systems might display scale invar iance.