I listed some major reasons why we age, such as DNA damage, epigenetic changes and mitochondrial dysfunction. Of course, there are other reasons why we grow old, and various others will be discovered. Below are a few examples of other potential causes of aging.
1. The transcriptome and aging
A decline in the transcriptome likely also contributes to aging. The transcriptome is the complex RNA machinery which carries the instructions from DNA to build proteins (apart from many other things it does). Accumulation or dysfunction of mRNA, tRNA, miRNA, lncRNA and RNA splicing all could contribute to aging.
2. Our gut microbiome and aging
During aging, our gut microbiome also changes. The gut microbiome contains about 40,000 billion bacteria which continuously secrete innumerable substances, many of which enter the bloodstream and contribute to our health (and disease). During aging, the gut microbiome becomes less diverse, and also more toxic and detrimental.
3. Bacteria and viruses contributing to aging
Lingering bacterial infections and viruses could also contribute to aging. We are surrounded by things that want to kill us or take advantage of us as parasites. In fact, as we speak, your body harbors about 380 trillion viruses (so around 380,000 billion viruses). They can be found in your lungs, skin, gut, blood, urine, and so on. Many of them do not really cause damage, but others slowly but steadily do, accelerating our aging process. For example, many people are infected with herpes virus type 1 and cytomegalovirus (CMV). These (and many other viruses) could contribute to the risk of Alzheimer’s, cancer, and other diseases (R,R).
In the future, we will likely see many other interesting mechanisms being discovered that contribute to aging, and the many aging-related diseases we all will eventually get.
