Validation of Exceptional Longevity

Age Validation of the Oldest Man

by A. Skytthe, B. Jeune, and J.R. Wilmoth


[ References | Annexes ]

This chapter concerns age verification on an individual basis, illustrated by a case study of the oldest man whose age has been thoroughly documented. We describe in detail the procedures applied with reference to the age validation criteria mentioned earlier in this book. We hope to demonstrate that this study is unique in several ways.

The case involves a Danish-born American citizen, Christian Mortensen (CM), who died in April 1998 at the age of 115 years and 252 days. The verification process has been described in an earlier paper (Wilmoth et al. 1996), but here we add some new evidence and address some general principles about the verification of age and identity.

One unique aspect is the fact that CM was an immigrant. It is often quite difficult to verify the age and identity of immigrants, because relations between native and adopted countries are torn apart. Having travelled extensively, CM stands in contrast to JC, a 122-year-old French woman, who was born, lived, and died in the same city (Robine and Allard 1995).

Another unusual feature is that we were actually able to communicate with CM. For many very old people, who often have severe sensory deficits, communication is a serious problem. Although CM was blind and had difficulty hearing during the time we knew him, until just months before his death he remained mentally aware and demonstrated a remarkable memory and a playful sense of humour. Since we were able to interview him directly, it was possible to perform a sophisticated two-way verification process, thus giving a much higher degree of confidence than if the verification had to rely on written evidence alone.


An official birth record (birth certificate or registration) is essential in order to perform an age verification. When dealing with living persons, birthday celebrations are often mentioned in newspapers and media, and from there the date of birth can be ascertained. However, one should not depend entirely on these secondary sources, as illustrated by the following story. A freelance journalist living in California, not far from the CM's place of residence, had for several years written about CM for a Danish newspaper on the occasion of his birthday. In 1997, however, this journalist wrote the story one month earlier than usual. Thus, the Danish newspaper reported the 115th birthday of CM exactly one month before his actual birthday, and several news agencies and television stations cited the erroneous date of birth.

Thus, the first thing to do in order to verify an individual's stated age is to locate an official birth record. This requires knowledge of where the registration has taken place. Typically, registration occurs at the place of birth (parish, county, etc.), since most births are recorded within the first few days of life.

As a second step in the verification process, it is of great importance to establish a time line of the person's life. This requires information containing verifiable dates from as many points during the life course as possible . Obviously, the age stated in each instance must be consistent with the age implied by the birth record. In evaluating the entire body of evidence, it is important to consider the possible interdependence between different sources - for example when a membership card is issued based on a birth certificate. Records from independent sources (such as, in most cases, successive government censuses) which are mutually consistent add credibility to the stated age.

In Annex A we present most of the available information from documents about CM. From this evidence, it is possible to make a time line where the unknown periods have spans of less than 10 years. After his birth in 1882, he is found in the census of 1890, 7 years old and living with his parents. His confirmation of baptism occurred at the age of 14, when he lived at a neighbour's house while working as a farm hand. In 1898, he moved to the neighbouring town of Skanderborg and became a tailor's apprentice. CM reported in interviews that this apprenticeship lasted 5 years, which means that he stayed in Skanderborg until 1903. In August of that year he went by ship to America and arrived at Ellis Island, in New York harbour, on 8 September 1903. After a few days, he travelled on to relatives in Chicago.

He stayed for a few years - it is not clear how many - in Chicago and worked as a tailor. In 1905, he joined the Danish Brotherhood in America, a fraternal organisation of immigrants and their descendants. For the period from 1905 until the U.S. census of 1920, no written documents have been found, but interviews with CM revealed that he travelled extensively around the western United States (from Chicago to California) from about 1908 to 1918. Around 1918, he returned to Chicago and settled for a longer period. He was married for a few years around 1920 but divorced sometime after 1923. In that year, sponsored by his wife's brother, he joined a Masonic lodge in Chicago. Also during this time, he worked as a milkman for the Borden Dairy Company. In 1929, he became a factory worker for the Continental Can Company, where he was employed for 21 years.

In 1950, CM retired and moved to south Texas, close to the Gulf of Mexico. He enjoyed sailing and reportedly built his own sailboat. Pension records show that he seldom lived in the same place for more than a few years. In 1978, at the age of 96 years, he moved to a retirement community in California, where he lived for the last 2 decades of his life.


The question of identity (Is the person in question the same one born on a particular date more than one hundred years ago?) is much more difficult to handle in a convincing manner. It is necessary to consider at least four issues:

In the case of CM, the first and second scenarios can be ruled out based on evidence about CM's family and his life history. First, CM's full name was unusually long, and when asked, he recited all five of his given names as they appear in the birth registration. No one in his family has names that even slightly resemble those of CM.

Secondly, according to parish birth records, CM was the youngest of 6 children, and his mother was already 40 years old at the time of his birth. In the Danish census of 1901, when his mother was 59 years old, a total of six births were noted for her (of which three children had already died, and three were still alive). The consistency of these two sources of evidence, plus the fact that the time line of CM's early years (i.e., education, apprenticeship, immigration to the U.S.) follows a logical progression, leaves little room for suggesting a switch of identity between siblings.

Concerning motives, a possible scenario is for an impostor to assume the identity of an individual without anyone noticing it. In order to avoid being discovered, an impostor merely has to stay away from places in which the person with the real identity was well known. For this reason, the identity of immigrants is particularly suspect. Motives for a change of identity might be to gain money, to avoid military service, or to evade responsibility for a criminal act. For rigorous verification of identity, these and other motives must be considered.

Although CM was an immigrant and left Denmark at the beginning of this century, eventually becoming an American citizen, we were again privileged in this case. Both of his brothers who survived until the middle of this century married and had children and grandchildren. CM visited Denmark several times during this century, especially after he retired from work. He was a guest at the celebration of one of his brothers' birthdays, probably the 70th birthday of his older brother nearest in age. In the beginning of the 1960's, CM visited Denmark and most of his family. His surviving relatives still remember this visit, and several newspaper articles appeared at that time with photographs of CM. When queried, some of these relatives could not understand how we might suspect a case of mistaken identity - to them there was no doubt about his authenticity.

Thus, thanks to a series of long and short stays in Denmark and to relatives who have known him for many years, a possible change of identity while in the U.S. appears to be entirely implausible. Of course, such a change could also have taken place many years before in Denmark. During the 1920's and 1930's, immigration to the U.S. became more difficult due to restrictive legislation. One possible way to circumvent these restrictions would be to assume the identity of a person already holding US citizenship. Is it possible, for example, that CM gave his passport to an impostor during an earlier visit to Denmark and that the impostor returned to the U.S. while CM stayed in Denmark?

One way of testing this hypothesis is to look for similarities of the person when young and when old. An example could be the height recorded as a young adult (e.g., during a physical examination for the military or when applying for a passport) compared with the height recorded at older ages. Similar physical appearance at two different times is one indication of the same identity, especially if a scar or birthmark is present. In the present case, CM passed a physical examination in 1905 when he applied for membership in the Danish Brotherhood. At that time, his height was recorded as 5 foot 4 inches (162.6 cm), which agrees very well with his present height - "5 foot 5 with shoes," in his own words. The height of CM in 1905 was about one standard deviation below the average height of his generation, and it can be argued that less than 1/8 of Danish males in his generation had a similar stature (see note 2 in Wilmoth et al. 1996).

Another, and more powerful, way of confirming identity is available if the person is still alive and it is possible to communicate with him (or her) directly. By asking questions about events, family, places, childhood, adult life, etc., it is possible to obtain information that can be compared with evidence from other sources. In this case, one of us (JW) performed a long series of interviews and obtained very detailed information about CM's close family and childhood, including a description of the place where he lived as a child. Due to the fact that the interviews took place in California, yet the documents concerning his family, birth, and childhood were present in Denmark, we had the opportunity to exclude a potential interviewer bias by, in some cases, not letting the interviewer know the answers to questions in advance. In addition, we were able to check and verify new information given by CM. Several months of this ping pong method of asking questions and verifying new information resulted in an overwhelming body of evidence confirming the identity of CM.

As an example of this method, let us focus on the number of his siblings. In our early investigation of the parish registers from the parish of Fruering, we identified four siblings, of whom two had died as infants before CM's birth. We knew that two older brothers, Carl Emil and Anders Julius, were still alive when CM was born, having been born 4 and 8 years earlier. Before a meeting with CM, the interviewer was told only the number of siblings. However, when queried, CM responded that he had three older brothers, not two: Johannes, who died from TB at the age of 31; Carl Emil, who died at the age of 92 in Aarhus; and Julius, who died at the age of 79 in Horsens. The information concerning the death of Carl Emil and Julius agrees well with information from the Danish death registry, except that Julius had died at the age of 72. But Johannes was an unknown brother (to us), and this finding provoked some scepticism. We soon realised that our earlier information was incomplete. Among other things, we had not found the marriage record for CM's parents in Fruering parish (and CM did not know where his parents were married). A search in the census of 1880 revealed that his parents were married in another parish, Søvind, about 25 km from Fruering, and that a child named Hans Johan was born in that parish in 1869 (in Danish, the difference between the names Johannes and Hans Johan is minor). A subsequent search in Fruering parish around 1900 yielded the death registration of Hans Johan at the age of 31. We also found the death certificate, which lists "consumption" as cause of death, probably the same as TB.

This example shows that information new to us as investigators could be verified subsequently, and that it was not enough to look only at information from the time when the person under investigation was alive - important information for the verification process was dated to the time before birth as well.

Another strong piece of evidence came from CM's description of the house and place where he grew up. A small stream from a spring runs very close to his boyhood home, and CM described to us how his father had sat outside the house close to this stream when CM told him that he was going to America. A visit to Skaarup today reveals that the stream is still there, although the house was torn down more than 50 years ago. Additional evidence comes from a description of a neighbour, a man CM called "the butcher." The man was feared by the children because he became very unpleasant when he got drunk and sometimes smashed the windows of their house. In a description of the small village of Skaarup, that particular neighbour is actually mentioned by the same nickname, "the butcher" (Andersen 1977).

Putting all these pieces together, there seems to be little, if any, room for doubt about the authenticity of CM's age and identity. The consistency of early records, and the fact that he was the youngest child in his family, make a switch of identity while in Denmark extremely unlikely. Likewise, a change of identity later in the U.S. is simply implausible given his very detailed description of his childhood and close family, and the existence of relatives who recognised CM during and after his visits to Denmark during the 1960's.


We wish to thank Paul Ørberg and Jens H. Frandsen for their help in locating CM's birth record and information from the Provincial Archive of Jutland. Also thanks to Maxine Weinstein for help in obtaining a copy of CM's immigration record from the National Archives in Washington, DC; to Diana Friou for her great work in collecting information in USA, and to Gudrun Hauge for her careful search for his ancestors.

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