Current View on Biology of Aging 1. Clinical Pharmacy and Biopharmaceutics Department, Faculty of Pharmacy, University of Jordan. * Correspondence should be addressed to: Violet Kasabri E-mail: v.kasabri@ju.edu.jo © 2010 DAR Publishers/ University of Jordan. All Rights Reserved. Violet Kasabri* 1 and Nailya Bulatova 1 Abstract This review article is based on a systematic literature search using Pubmed and keywords aging and senescence, interchangeably. Aging (senescence) is the progressive deterioration of many bodily functions. It may or may not be linked to disease, disability and loss of independence. Populations worldwide are aging. Theories of aging biology are interactive and interdependent. They fall into programmed theories and error or damage theories. Longevity genes are under scientific scrutiny, via utilising microarray technology, founder populations and centenarians’ family history. Telomere shortening is another programmed theory to explain healthy senescence. Biochemistry of the endocrine theory includes hormonal deficiencies, growth factors and heat shock proteins. Immuno-senescence furthermore elaborates the programmable aging. Among many of error/damage theories are free radical theory, mitochondrial dysfunction, membrane hypothesis of aging, protein cross-linking and DNA repair and maintenance. Biomarkers of aging, as in senescence marker protein-30 and klotho protein, offer the feasibility for exploring aging biology and physiology, advancing our understanding of genetic and lifestyle contributions to aging, and, at best, developing effective age-defying interventions. Keywords: Aging, Senescence, Theories of Aging, Longevity, Biochemistry of Aging. (J Med J 2010; Vol. 44 (2):181-192) Received Accepted April 16, 2009 July 30, 2009 Introduction In its broadest sense, aging (senescence) is the progressive universal decline first in functional reserve and then in function that occurs in organism overtime. This loss of function is accompanied by decreased fertility and increased risk of mortality. Aging is heterogeneous. It varies widely in different individuals and in different organs within a particular individual. Aging is not a disease. However, the risk of developing disease is increased often dramatically, as a function of age. 1, 2 Demography of Aging: A Global Perspective Populations worldwide are aging. Improvements in environmental factors (sanitation and clean water), behavioral factors (nutrition and reduced risk factors), vaccination (prevention of infections), and disease treatments are largely responsible for the 30-year increase in life expectancy since 1900. 3 Between 2000 and 2030, the number of older adults worldwide is expected to increase from 420 to 974 million. At present, 59% of older adults live in the developing countries of Africa, Asia, Latin America, the Caribbean and Oceania. The developing world has the largest absolute number of older adults and is experiencing the largest percentage increase.