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The Slump Surname Project

Updated: Nov 18, 2022

Slump surname project

The Slump Y-DNA surname project was started at Family Tree DNA (FTDNA) in Dec 2017. The SLUMP surname was adopted in Lemsterland, Friesland, The Netherlands in 1812. Prior to this, the family used patronyms. Ancestors were in Overijssel and Drenthe in previous generations. Related men, unbeknownst to their other family members, may have adopted different surnames. Some immigrants to the United States adopted different surnames, including Slumpff, Stumpf, and Tavares. Thus, the project will admit men who had Y-DNA matches, even though their surname may not be SLUMP.

There are also SLUMP from other regions. They will likely have differing genetic markers. We are happy to include them and help understand their origins.

Joining the Slump project is easy. There are several options:

  1. If you have already tested Y-DNA at FTDNA, click on the Project tab at the top of your kit login page. Then, click Join Project and search for Slump. Click on the project link and join.

  2. You can go to the project public web page and click the "Join Project" tab. The click the link "Purchase A Test To Join This Project." You may see a message that you cannot join; it's not true. Click on the S cell in the surname grid. The either search for Slump or scroll down to it. Click on the Slump link and order the desired Y-DNA test. Y-37 is sufficient for an initial test.


What is a surname project

As used here, a surname project refers to a Y-DNA study of those men whose patrilineal descent is from a man with the surname Slump. Y-DNA is passed strictly father to son undiluted through many generations. Thus, it can be used for genealogy of distant ancestors. While the Y-DNA is relatively stable, there are occasional mutations, which create branches in the human haplotree. These branches are defined by specific single nucleotide polymorphisms (SNPs) from which the branch takes its name. The currently known most recent branch on the Slump patrilineal line, determined by the Family Tree DNA (FTDNA) Big Y test, is R-S25738. Branches are also known as clades.


Y-DNA research has several purposes:

  1. It can verify historical records by showing Y-DNA matches between males whose historical records lead to a common ancestor.

  2. It can discover relatives previously unknown to the tester who may have additional genealogical information about the family

  3. It can discover relatives with different surnames, which can occur through several mechanisms:

  4. Registrations by related men of a distinct surname which, in the Netherlands occurred during the French occupation.

  5. Adoption by non-biological parents, whose surname the adoptee acquired.

  6. Paternity not through marriage in which the mother's surname is retained by the child.


  1. New haplotree branches can be identified when a sufficient number of test results are available. The rate of growth of the haplotree is now quite high and we can expect smaller twigs beyond the current terminal SNP, R-S25738.


The haplotree branch leading to this SNP is quite deep in the hierarchy:

R-M207 > M173 > L754 > L389 > P297 > M269 > L23 > L51 > L151 > U106 > Z2265 > BY30097 > Z381 > Z301 > L48 > Z9 > Z30 > Z27 > Z345 > Z2 > S15510 > Y7378 > Y7404 > S8958 > S20654 > R-S25738

Men in the patrilineal descent of Slump are encouraged to order a Y-DNA test from FTDNA where the surname project is organized. The test involves swabbing the inner cheek; thus, it's easy and painless! The Y-37 test measures 37 short tandum repeats (STRs) and is a good starting point. STRs are different than SNPs. Y-37 testing will match with other Slump men, but usually with enough data to place them on the haplotree at R-M269. More refined testing can take two forms:

  1. The Big Y test. This requires a previous Y-37 or similar STR test to enable quality control. It is expensive, but powerful for genealogy research.

  2. Terminal SNP test. Since we already know that R-S25738 is our clade, one can test directly for this for much less cost (currently ~$40). We assume that all Slump will test positive, but it is possible there was an earlier, presently unknown branch that would render this test negative.

You can see from the branch structure that a more ancient branch for us is R-U106. There are projects for this haplogroup and it computes the time when the various branches emerged. You can see this graphically or in a text format. Search for S25738 to find our branch (also called a clade or terminal SNP). The statisticians compute its emergence in 194 AD (confident intervals 433 BC to 745 AD).


Right now, I have 3 Big Y matches for R-S25738 (see figure) in the U106 clade project. I may be starting a FTDNA haplogroup project for this R-S25738 clade. This will likely help us refine our knowledge of this clade. If we have more Big Y testers, we can move further out on the branches and this will narrow and get a more recent time range for the branches. It may also get us to a smaller geographic area where the branch emerged.














Origins of the Slump surname

Surnames were mandated in The Netherlands during the French occupation. Our clan adopted the SLUMP surname, registering it in Lemsterland, one of the municipalities in the Provence of Friesland. One registrant was Harmen Pieters Slump [65] (1750-1823), my direct ancestor. He was born in Giethoorn, Overijssel (an adjacent province). His two brothers had separate registrations, but also adopted the Slump surname. There may have been Slump registrants in Overijssel, but these records are not available online at present; if any readers have such Slump registrations, please communicate with me.

These naamsaanneming (name adoption) registrations are shown below, but can also be accessed online.


Registration of Harmen Pieters Slump [65] (1750-1823): Oosterzee, Echten, Eesterga, Follega; Archiefnaam Register van familienamen; Archiefnummer 29; Inventarisnummer 0081. The registration includes himself and some of his children: Grietje Harmens Slump [1354] (1778-); Roelof Harmens Slump [33] (1779-1850); Jacobje Harmens Slump [1355] (1780-); Petrus Harmens Slump [1357] (1784-); Peigje Harmens Slump [1358] (1786-); Jan Harmens Slump [1359] (1788-); Gerrit Harmens Slump [1362] (1800-); Grietje Harmens Slump [1363] (1802-); Jan Harmens Slump [1364] (1804-1856).



Registration of Hendrik Pieters ` [1380] (1748-1753): Oosterzee, Echten, Eesterga, Follega; Archiefnaam Register van familienamen; Archiefnummer 29; Inventarisnummer 0081.




Roelof Pieters Slump [717] (1743-1814): Oosterzee, Echten, Eesterga, Follega; Archiefnaam Register van familienamen; Archiefnummer 29; Inventarisnummer 0081.



The Slump Patrilineal Tree

Slump relatives have created a diaspora. As they disseminated to the United States, Canada, Australia and elsewhere, the name was sometimes changed, for example to Slumpff and Stumpf. The patrilineal tree currently know to this author is illustrated at this link with those living anonymized.

Slump ancestors living before the adoption of surnames used patronyms. Y-DNA match are possible with men whose most common recent ancestor (MRCA) lived many hundreds of years ago. Thus, Y-DNA is quite likely to discover matches with men who have different surnames. Indeed, other men within the R-S25738 clade have other surnames.

Questions? Please contact me.

You have several options:

  1. Write a comment on this blog post. Others will see this too and also benefit from my responses.

  2. Email me: genealogy@stumpf.org.

  3. Snail mail: 1101 Alpine Ln; Woodstock, IL 60098; USA.

More background on me: http://woodstockhit.com/stumpf_resume.html