Top 12 Theories of Aging
Aging is a slow and continuous process which occurs over time and is highly predictable. Our lifestyle, level of stress, hormones, habits, medical history, genes and environment decides over the process of ageing. Several biological, social, physical and psychological changes occur during the ageing process. According to researchers, some biological theories are associated with ageing. The top theories are mentioned below –
- Telomere Theory – Telomeres are structures located at the chromosomal ends. Several experiments have proved that the length of the telomeres has shortened over repeated cell divisions. After achieving a certain shortage in telomeric length, a new mechanism to prevent further cell multiplication is activated. This results in initiation of the ageing process within tissues which require subsequent cell divisions. Tissues of the bone marrow and arterial linings require continuous cell division for proper functioning.
- Reproductive-Cell Cycle Theory – According to this theory, certain reproductive hormones act as a restrictive force against the procedures of cell cycle signaling, early development and growth to ensure growth and development. Over time, these hormones get deregulated and become incapable to perform their actions. This gradually leads to stopping of growth and starting of ageing.
- Wear-and-Tear Theory – Several damages occur inside our body over time. Accumulation of such damages results in ageing.
- Somatic Mutation Theory – When damages occur in the genetic constitution of our body, it gradually leads to ageing.
- Error Accumulation Theory – During replication several proofreading activities occur. Sometimes, the proofreading activities are missed by chance. This leads to damage to the genetic code. Gradual accumulation of such genetic damages results in ageing.
- The Viral Theory of Aging – Damage to the DNA (Deoxyribose nucleic acid – the basis of life) is considered as the prime cause of ageing. Several causes like chemical exposure, viral infections and radiations are the prime causes of starting of the aging due to damages to the DNA. Maximum harm is done due to viral infections.
- Evolutionary Theories – All speculative and unsolved theories of ageing are placed under this category. No proper scientific evidences are available.
- Accumulative-Waste Theory – This theory states the involvement of body wastes in the ageing process. The gradual accumulation of body wastes starts interfering with the usual metabolism procedures. Thus initiating ageing.
- Autoimmune Theory – With the increase in number of autoantibodies, the number of attack also increases over the body tissues. Several diseases like Hashimoto’s thyroiditis, atrophic gastritis are all involved to the ageing. These diseases occur after the initiation of the process of aging. Similarly, aging might also be linked to the autoimmune responses.
- Ageing-Clock Theory – Researchers believe that there are certain preprogrammed sequences present within the endocrine system and nervous system of the body. These work like a clock to control all body activities and initiate the process of ageing.
- Cross-Linkage Theory – Some cross-linked compounds interfere with the normal functioning of cells. Accumulation of such compounds often blocks the cell activity and triggering aging in the organism.
- Free-Radical Theory – Highly unstable and extremely reactive organic molecules are present in our body. These are called free radicals or oxidative stress and reactive oxygen species. These free radicals can cause damage leading to symptoms caused during aging.