What happens in the body when we age? What are the biological bases for the ageing processes? These are precisely the questions we want to answer at the Max Planck Institute for Biology of Ageing. We all know the external features that appear in old age, such as wrinkles, sagging skin, grey hair and the decrease in height. But we do not know what exactly happens in the cells.
Researchers are discussing different approaches that might explain the ageing process. Some theories explain the process of ageing with damage to genetic material, cells and organs that increases over the entire life span and cannot be repaired by the body. In addition, there are accumulations of harmful by-products of metabolism and clumped proteins that the cell is no longer able to eliminate. One of the best-known damage theories is the theory of free radicals. According to this theory, free radicals, which are produced in the mitochondria during cell respiration, damage important molecules in the cell. As these damages accumulate over time, this causes the aging process. The telomere hypothesis of ageing provides another explanation for ageing. Telomeres are the ends of the chromosomes of the human genome. They are comparable to the sealed end of a shoelace and keep our chromosomes stable. With each cell division, a piece of the telomeres is lost, so that the chromosome ends shorten more and more the older we get. The telomeres are thus a unit of measurement for our biological age. When a certain minimum length is reached, the cell enters the dormant phase and no longer divides. Such cells can then die or even cause inflammation, speeding up the ageing process and triggering diseases. Another theory focuses on stem cells and their decreasing ability to regenerate with age as the main cause of ageing processes and age-related diseases.
There are also evolutionary theories that focus on the potential biological benefits of ageing and see ageing as the result of an evolutionary process. For example, the origin of ageing can be seen in the accumulation of harmful gene mutations in the course of life resulting in dysfunctional cellular components and repair mechanisms. However, since most living creatures in the wild die from injuries, lack of food or from predators before reaching their maximum life expectancy, no repair mechanisms have developed during evolution to stop the ageing process, according to the evolutionary theory. In addition, ageing and death may be advantageous because it provides more resources for the young. As old creatures die, the young are given more space and food, which improves their chances of survival.
With our research we want to decipher the underlying mechanisms that could explain the various theories and identify the signalling pathways in cells and organisms responsible for ageing.