Jansen

Before the French administration reached the Low Countries, a Dutch family name changed with every generation. A boy born to a man called Jan was Pieter Janszoon and his sister Geertje Jansdochter. The forms wore down in use to Janszn. and Jansz, to Jansdr., then to Jansse, and finally to Jans, which served for sons and daughters alike. These were not casual nicknames. They were official, written into legal instruments, and inheritances can be watched passing from father to son under two different surnames.

The Napoleonic Code, established in France in 1804, stipulated that a person be known by a given name and a family name that would not change across generations, and it travelled wherever French power did. The Netherlands was drawn under that system between 1795 and 1811, and the forced registration of 1811 ended the old practice in a single administrative act. Whatever patronymic a household happened to be using that year became its permanent surname, and Jansen was frozen exactly where it stood, alongside Peeters and Willems. That is part of why the country now carries more than 100,000 surnames, the Meertens database counting 94,143 of them.

One story about that year refuses to die: that Dutch families mocked the clerks with absurd names, Naaktgeboren (born naked) or Zondervan (without surname). Both are in fact far older than 1811. The real mechanism was duller and stronger. Custom gave the first-born son his paternal grandfather's name and the second his maternal grandfather's, so a favoured name returned every other generation, and Jan, the Dutch Johannes, was the most favoured of all.

The earlier was Cornelius Jansen (1510-1576), a Flemish religious leader who became Bishop of Ghent and is still distinguished in the record as Jansen of Ghent. The later was Cornelius Jansen (1585-1638), the Dutch theologian whose surname was taken up by Jansenism, carrying an ordinary patronymic into every later history of the early modern church. Between them worked Hendrik Jansen van Barrefelt (c. 1520 - c. 1594), a Dutch Christian mystic whose full name keeps the patronymic in the middle, where it began.

The clerical line kept its hold. Johannes Henricus Gerardus Jansen (1868-1936) rose to Dutch Archbishop. Arnold Janssen (1837-1909), a German-Dutch Roman Catholic priest and missionary, was canonised a saint. John Janssen (1835-1913), German-born, served as a Roman Catholic bishop in Illinois; Johannes Janssen (1829-1891) was a German historian and priest; in Norway the priesthood took Jens Jonas Jansen (1844-1912).

Zacharias Janssen (1585 - before 1632), whose name is also written Sacharias Jansen, ground lenses for a living. He is credited as a co-inventor of the telescope and of the compound microscope, which puts an unfixed Dutch patronymic on both instruments.

The other Janssen in the sky is French. Pierre Janssen, also published as Jules Janssen (1824-1907), was an astronomer whose name now sits on a lunar crater and a Martian crater, on Janssen Peak in Antarctica, and on the Janssen Medal awarded for astrophysics by the French Academy of Sciences; his revolver camera originated chronophotography. The laboratory line ran on through Barend Coenraad Petrus Jansen (1884-1962), Dutch chemist and biochemist, and Ted Janssen (1936-2017), Dutch physicist.

Gheerart Janssen the elder (died 1611) was a Dutch sculptor who ran a monument workshop through Elizabethan and Jacobean England. The business passed to his son, Gheerart Janssen (fl. 1612-1623), still working in England in the years after his father's death.

A second English line came through money. Theodore Janssen (c. 1658-1748), French-born, made himself an English baronet and financier. His son Abraham Janssen (c. 1699-1765) held the baronetcy and sat as a politician; Stephen Janssen, 4th Baronet (died 1777) went further, serving as an English Member of Parliament and as Lord Mayor of London. Another Abraham Janssen (1720-1795) is remembered instead as a British chess player.

Roeliff Jansen (1602-1637) was a Norwegian who settled in New Netherland, carrying the name to America while it was still a working patronymic rather than a fixed surname. The older habit held there too: Rutger Jansen Bleecker (1675-1756), Mayor of Albany, New York, kept Jansen as a middle element, in exactly the position it had held in the Low Countries.

The name also reached the top of the city itself, with Johannes Jansen (1665-1734) serving as Mayor of New York City from 1725 to 1726. In the nineteenth century it surfaced further west: Edward H. Janssen (1815-1877), German-born, was Treasurer of Wisconsin from 1852 to 1856, Henry J. Janssen (1876-19??) followed him into Wisconsin politics, and Peter Jansen (1852-1923) into Nebraska's. DeWitt Clinton Jansen (1840-1894) carried it furthest, an American hotelier and politician who was also a judge in Shanghai.

South of the Dutch border the spelling doubles. Janssens is the second most common surname in Belgium, where the leading names are almost entirely patronymic, De Smet (the smith) standing out as the exception. Janssen is the seventh most common surname in the Netherlands, and counted together with Jansen the two spellings cover more than 131,000 people, making them jointly the commonest name in the country.

Belgian Janssens built institutions. Constant Janssen (1895-1970), a physician, founded the predecessor of Janssen Pharmaceutica; Paul Janssen (1926-2003), also a physician, founded Janssen Pharmaceutica itself, and the Dr. Paul Janssen Award for Biomedical Research carries the name still. Emmanuel Janssen (1879-1955) founded the chemical company Union Chimique Belge, and his son Charles-Emmanuel Janssen (1907-1986) followed him into business and politics. Albert-Édouard Janssen (1883-1966) was a monetary theorist and Minister of State, Georges Janssen (1892-1941) governor of the National Bank of Belgium from 1938 to 1941, and Geneviève Janssen-Pevtschin (1915-2011) the first female magistrate in Belgium.

In Germany the name attaches to a run of people who made things to be looked at. Peter Janssen (1844-1908) painted history pictures, Karl Janssen (1855-1927) worked as a Baroque revival sculptor, and Horst Janssen (1929-1995) drew, printed and made posters on a scale sufficient to fill the Horst-Janssen-Museum named for him. Hermann Jansen (1869-1945) worked at the largest scale of all, as an architect and urban planner.

In Scandinavia the same patronymic produced Jensen and Jansson, but the Dutch and Low German spelling travelled north too. Peter Jansen Wessel Tordenskiold (1690-1720) became a Norwegian naval hero with the patronymic still lodged mid-name. Heinrich Jansen (1625-1667) painted in the Danish Baroque and Ewert Janssen (died c. 1692) built in it. Then the name turned to record-keeping: Einar Jansen (1893-1960), Norwegian historian, genealogist and archivist, and Ea Jansen (1921-2005), Estonian historian.

In South Africa the name settled into compounded forms, Jansen van Vuuren and Jansen van Rensburg, borne by rugby players and by Laura Jansen van Vuuren (born c. 1958), an admiral in the South African Navy. The plain spelling stayed too: Ernest George Jansen (1881-1959) in South African politics, Robbie Jansen (1949-2010) in South African music, the cricketer Marco Jansen (born 2000).

The modern record is mostly won rather than written. Jan Janssen (born 1940) won the Tour de France in 1968; Wim Jansen (1946-2022) was a Dutch footballer; Dan Jansen (born 1964) skated for the United States. The concert platform holds the violinist Janine Jansen (born 1978) and the pianist Rudolf Jansen (1940-2024), the screen David Janssen (1931-1980) and Famke Janssen (born 1964).