Why were we born human

How old can people get?

The dream of eternal life

Reinhard Güll

A central element of being human from a philosophical and scientific perspective is the awareness of one's own death. In the history of mankind, the dream of eternal life, which can be found in almost all religions and many myths, is closely connected to this content of consciousness. This dream has not yet been realized and will probably remain a wish given the current state of science. However, people's hope for a longer life is no longer a wish. Official statistics can provide some answers to this.

From the earliest times there are reports of people who are said to have reached a particularly old age. The biblical Methuselah, which according to the book of Genesis of the Bible lived to be 969 years old, is particularly well known. His name is still used today as a synonym for a very old person. In most cases of the ancient reports, the ages could not be proven due to the lack of reliable sources such as birth and death certificates. Since the years were counted twice in different areas up to the early 20th century, summer and winter were separated, many traditions are also questionable for this reason. This double counting was mainly practiced in the rural areas of Tsarist Russia. The counting uncertainties changed only slowly with the advancing development of the civil status system. Many countries already had birth certificates in the late 19th century. This made the search easier and reduced the chances for fraudsters and impostors to pretend to be older than they actually were. The first person to be proven to have reached the limit of 110 years was Geert Adriaans Boomgaard from the Netherlands. He was born on September 21, 1788 in Groningen and died there on February 3, 1899. The first woman who was proven to be 110 years old was the Englishwoman Margaret Ann Neve, who was born on May 18, 1792 on the Channel Island of Guernsey came and died on April 4, 1903. The oldest person reliably documented today is Jeanne Calment (February 21, 1875 - August 4, 1997). The French woman was born in the city of Arles in Provence. Its 122 years and 164 days represent the longest unequivocally documented lifespan.

About 2,000 people over the age of centenarians have certainly been attested in history in a project by the Max Planck Institute. At the end of the 2000s, the research results of independent researchers were compiled in an international project of the Max Planck Institute for Demographic Research in Rostock and in 2010 in the monograph »Supercentenarians«1 released. These are undoubtedly only a fraction of those who actually lived, since the lifespan of the majority of these people has not been recorded and documented. In these evaluations, the oldest women reach a slightly older age than the oldest men. This statistically significant difference is about 3 years. There are different theoretical explanations for this advantage for women. On the one hand, the higher maximum life span of women is often explained with the same theories as their higher average life expectancy. Another group of theories regards the advantage of women as being given by fate and nature, so to speak, because the male hormone balance or other specifically male body characteristics would lead to a somewhat faster wear and tear of the body. A third group of theories sees the difference more as a consequence of gender-related roles, since men are more often used in wars, hazardous work and physically damaging activities. They also see a doctor less often if they have symptoms of the disease. In addition, men smoke and / or drink alcohol more or more often.

Almost all age record holders come from the comparatively rich countries of the north, from Europe, Japan, North America, but there from all ethnic groups. As early as 1890 there were 78 people living in Germany who were 100 years of age or older (see Table 1). One of the reasons why there are no corresponding reports from the so-called »Third World«, in which the far greater part of the world's population lives, is that due to poor medical care, illnesses, lack of nutrition, poor education and other factors, people suffer poorer countries have a far lower chance of surviving the first 100 years and then fewer people remain who can reach their maximum lifespan. Another reason is the registration of births in the countries mentioned, which was rather patchy, especially in the 19th century.

The data shown in this project has increased in the meantime. In 2018, there were already 1,734 people aged 100 and over in Baden-Württemberg alone (see Table 2). The reason for the steady aging of the population is assumed to be that the current age structure is ultimately a product of the demographic events of the previous 100 years.2 In addition, there are factors such as a well-developed health system, relative prosperity for broad sections of the population, the lack of natural disasters and the fact that there have been no armed conflicts in Germany for 75 years.

Even if not all people in Baden-Württemberg have reached the biblical age of 100 years or more, their life expectancy has risen continuously over the last few decades. Life expectancy is the average expected length of time that a person will have from a given point in time to death, based on certain assumptions about death rates. These are usually determined with the help of a mortality table, which is based on observed mortality rates in the past and on model assumptions for their future development. In principle, the point in time from which the remaining life expectancy is to be determined can be selected as desired. In the general case, it is the period that begins with the biological development of the living being, that is, at birth. Life expectancy at birth indicates the average age that the newborns of a certain age group would reach if the age-specific mortality rates remained constant in the future. Often the total population of newborns is not considered, but a subpopulation selected according to certain criteria, such as the population of a federal state or the population of women or men. Unless populations are decimated by wars, genocides, natural disasters, migrations, epidemics, famine or, in individual cases, accidents, the genetic predispositions of biological life expectancy, quality of medical care, stress, nutrition and exercise play an important role. Under the best framework conditions, people can then live to be 100 years or older.

Baden-Württemberg currently has the highest life expectancy in Germany. A newborn boy in Baden-Württemberg today can count on an average life expectancy of 79.7 years. For a newborn girl it is 84.1 years. This is evident from the most recent life table calculations for the period 2016 to 2018. This means that the life expectancy of newborns is almost 10 years higher for women and 11 years for men than it was in the early 1970s. At that time, the average life expectancy at birth was 68.5 years for boys and 74.5 years for girls. The difference in life expectancy between women and men has narrowed since the mid-1990s. Back then, women lived an average of 6.4 years longer than men, while it is now only 4.4 years. Within Baden-Württemberg, the female population in the Breisgau-Hochschwarzwald district currently has the highest life expectancy, followed by the Heidelberg and Ulm districts. The life expectancy of women is lowest in Mannheim. The life expectancy of men is also highest in the Breisgau-Hochschwarzwald district, followed by the Böblingen and Tübingen districts and the Lake Constance district. The men in the Mannheim district currently have the lowest life expectancy. If the framework conditions remain the same or even better, the average life expectancy of people in Baden-Württemberg could increase even further in the next few decades.

In search of the source that makes people in the best of health and physical fitness very old, researchers have now at least discovered the source of aging in a study: It is the hypothalamus, a large area in the brain that contains hormones and Messenger substances affect almost every body function, be it growth, reproduction or metabolism in general.

Another research approach comes from David Sinclair, an Australian geneticist who conducts research at Harvard near Boston, USA. He considers aging to be a disease - a particularly important disease as it increases the risk of a variety of other ailments. If one day it was actually possible to treat aging, all old-age diseases could be treated at the same time - from heart attacks to cancer, from type 2 diabetes to Alzheimer's. That would be incredibly cheap and incredibly effective. In Sinclair's vision, people will live to be an average of 120 years in just a few decades. In his work "The End of Aging"3 he gives an overview of the current state of research and reports that science is increasingly understanding how and why we age. As soon as we are conceived, for example, epigenetic structures begin to change systematically. These are chemical appendages - such as methyl or acetyl groups - that sit on and next to the genes and help the cells to regulate the activation of their genes. The longer we live, the more these switches and dimmers are flipped. In most cells, this changes the environment of an increasing number of genes in such a way that they can no longer be used. The cells develop, change their identity, they build up a memory. There are more and more scientists who suspect a biological program behind this constant genetic modification: aging.

According to Sinclair's thesis, the cells only have a limited amount of enzymes that rebuild our epigenomes - i.e. the epigenetic programs in the respective cells. For example, these enzymes attach methyl groups to the genetic material DNA or remove acetyl groups from certain packaging proteins around which the DNA is wrapped. If our cells are challenged in the course of life, for example because they have to repair damage to the DNA, they need epigenetic enzymes in places where they are otherwise not needed. They leave their whereabouts and return there after their work is done. According to Sinclair, mistakes happen in this process. The cells keep losing a tiny part of their identity. Sinclair calls this process epigenetic noise. The information about the regulation of the genes becomes less precise the longer we live. The risk of inflammation and disease increases. The age researcher believes that this is the reason why, for example, our hair turns gray. It is also the reason why our skin becomes wrinkled. And what's more, it's why our joints start to hurt. The epigenetic noise is also responsible for all the biomedical signs of decay that science treats as possible triggers of aging: from the exhaustion of stem cells to cell aging and mitochondrial dysfunction4 and the rapid shortening of the telomeres5.

Using cell cultures and model organisms, Sinclair and many other researchers were able to show that metabolic messengers change the activity of epigenetic enzymes. For the organism, the persistent food shortage is an indication of critical living conditions. The cells therefore switch epigenetically to a kind of life extension program. They invest more energy in the production of substances that keep them young, stabilize the epigenetic programs and protect them from harm. At the same time, they divide more slowly.

Biogerontologists hope that being able to live healthy well into old age will become a reality in the foreseeable future. Because biological aging research brings us more and more knowledge about why and how we age people. Whether cancer, heart disease or dementia, in the future it should be possible to treat such diseases, which occur more frequently in old age, preventively at an early stage.

The question arises, however, do we really want to postpone aging and its consequences further and further and thus increase the average human life expectancy to 120 or 150 years? Will it even be possible to completely abolish aging at some point? So will the dream of eternal youth become a reality in the future? If it is initially only about slowing down aging, the serious question arises, what are the effects of this first step? It is not yet possible to foresee what effects this may have on humanity. Because not everything that is or will be genetically feasible is ethically justifiable.

1 Maier, Heiner / Gampe, Jutta / Jeune, Bernard / Robine, Jean-Marie / Vaupel, James W. (Eds.): Supercentenarians, Max Planck Institute for Demographic Research. Rostock 2010.

2 Cf. Brachat-Schwarz, Werner: "More and more older people in Baden-Württemberg", in: "Statistical monthly magazine Baden-Württemberg 12/2019".

3 Sinclair, David A./Laplante, Matthew D .: The End of Aging. Cologne 2019.

4 The term mitochondrion or mitochondrion is a cell organelle that contains its own genetic material. They are regarded as a kind of »power plant of cells«. Source: Wikipedia.

5 Telomeres are the ends of the chromosomes. With each cell division, they get shorter. Source: focus online.