Do you know humans can live up to 121 years, which is the full potential of the species known to survive! Other species like a dogs can live up to 20 years, laboratory mice can live up to 4.5 years, drosophila fruit flies can live up to 3 months. Still, some animals like tortoise and trout fish are undetermined. But predicted to have approximately 150 years. So the living expectancy of species directly points out age/ageing. Ageing can be defined as time-related deterioration of physiological function necessary for survival and fertility. Studying age is a mysterious topic for researchers from the last century. Let’s explore interesting information behind the ageing process.
Gerontology
Gerontology is the scientific analysis of physical, mental, social changes, and biological changes that occur as people age.
It explains studies related to ageing like how it affects health, societal impact, dimensions of diseases, and biological and psychological perspectives.
Let’s dive deep into the reasons for ageing from a biological perspective.
Causes of ageing
Cellular senescence
Cells in our body has its potential time period to function. When a cell stops the function and it releases some harmful chemicals this indicates senescence. This senescent cells has negative impact on neighbour cells also. Stress and damage can lead cells to enter senescence. These cells will accumulate over a period of time in humans. A recent breakthrough found that removal of senescence cells in mice will extend lifespan, which is significant to animals also and drugs which destroy and silence these cells are called “senolytics”.
Wear and tear theory
It is estimated that DNA in our cells gets damaged ten lakh times per day. Detection and Repair mechanisms in cells will take care of this process. Still some damage may become irreparable and this accumulates over a period of time, so this DNA damage will lead to senescence. This “Damaged DNA” will lead to abnormal protein production in our body that may affect “genomic instability”.
When cells in our body struggle from damage recovery it leads to ageing. Genetic defects in repair mechanisms leads to premature ageing.
Reactive oxygen species
People who consume excessive fat have a high chance of premature ageing due to free radicals produced by the process of lipid peroxidation. These free radicals are Reactive oxygen species that damage the cells. So we can visibly observe that people who are very obese and fatty have lazy behaviour. Metabolism plays a very
prominent role in ageing. Mitochondria which is the power house of the cell will reduce oxygen for metabolism. Sometimes it reduces insufficiently to reactive oxygen species which is a subset of free radicals. ROS includes hydroxyl ion, superoxide ion and hydrogen peroxide, etc. These will have a negative impact on cell structure.
Mitochondrial Damage
Mitochondria is the powerhouse of cells, which supplies ATP a key component for energy. They use oxygen to produce energy in a process called mitochondria respiration. Any damage to this organ influences ageing. The genetic component present in this organ is Mitochondrial DNA (mtDNA). It is often damaged by free
radicals and some findings point out that a high mutation rate in mtDNA has a short lifespan and premature ageing.
Telomere shortening
In our cells, DNA is in condensed form as Chromosomes. These contain protective caps called Telomeres. This helps us to keep our chromosomes intact. At the time of cell division, some parts of telomere will be lost. If the cell divides more and older we will be. This will end in the shortening of chromosomes. Enzyme
telomerase prevents the shortening of chromosomes. But here only “our reproductive cells contain this enzyme and our body cells lack”.
Epigenetics
Our environment plays a vital role in the functions of genomic material. Influence of environmental factors in our DNA is called Epigenetics. Chromosomes are packed with histone proteins and by process of methylation. Any damage to this structure leads from environment factors, have a correlation to the ageing. Recent research reports say that changes in histone proteins have an impact on ageing.
Proteostasis
Proteins are building blocks of our body. For cells to function properly proteins must be kept in good condition known as protein homeostasis. This proteins are regulated by the system. If any damage happens to this system, it leads to loss of proteostasis; its a sign of ageing.
Running out of Stem cells
Whenever any damage happens to our body cells it will be replaced by “Stem cells”. Stem Cells can divide and differentiate into different types of cells. Research suggests that as we get old stem cells also get depleted and reduce their ability to repair. Recent studies have given good hope to the rejuvenation of stem cells. Findings pinpoint that blood plasma from young mice was transferred into old mice improves stem cell function; therefore this rejuvenation approach leads to healthy ageing.
Gut microbiome
Our human body is dominated by numerous microorganisms and it helps us to build good immune system, helps to digest, helps to produce essential vitamins and fight off pathogen. Intestinal bacteria (microflora) have a predominant role in the gut. Gut microbiome plays a vital role in ageing. Research proves that
“supercentenarians” who lived a long life contains (good) microbes in their gut as young people have. Imbalance of gut microbiome due to pathogenic bacteria leads to ageing.
In this article, I have discussed elaborately the causes of ageing. Part – 2 of this article will give you insights on the measurement of age, diets, dynamics, why women outlive men, the blue zone and slow down of ageing.
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Hello ,Sankara , Its Quite interesting and fascinating because it helps us understand how and why our bodies change over time . and beautifully explained the facts and waiting for the part 2 with a knee interest to know more about it and i have a question that What are your thoughts on the biggest challenge people face as they age—do you think it’s more physical, emotional, or social? Looking forward to hearing your perspective!”