On the evening of Friday August 21, 1998, my teacher, mentor and best friend Hans van Abeelen and his wife, Janny Brinkman van Abeelen, would have arrived at my place in Orléans for a weekend visit. This was not to be. Totally unexpected, Hans died in his sleep in the early hours of that morning, at the side of his beloved Janny. When I arrived at his home on the next day, his suitcase was still standing ready for his visit. In it was a small gift, which he had intended to give me upon arrival in Orléans. It was a small book, clearly chosen with care to match my personal interests. This was something quite typical of Hans and his warm interest in all human beings, especially those whom he regarded as his friends. Curiously, this side of his personality went often unperceived by others and, indeed, it took some time for me to discover this aspect, too.
I first saw Hans in late 1974, during the second year of my biology studies at the University of Nijmegen, where he taught a course entitled "Quant- en Phenogenetica" (Quantitative and Phenotypical Genetics), together with his late colleague Piet van der Kroon. His lectures were quite inspiring to me. Enough so to approach Hans to prepare my Master's thesis in his laboratory. Hans agreed to this and I worked in his lab from September 1976 to September 1977. This work led to a publication (my first!)  and, from then on, our contacts became ever more intensive. In 1979, I started working in his lab as a graduate student, obtaining the Ph.D. in January 1984. During this time, his vast experience and knowledge of the field of behavior genetics, which he willingly shared with me, showed me how much I still had to learn.
When I left The Netherlands for a postdoc abroad, I more or less expected the contact to wane, but I soon discovered that Hans kept a warm interest in everything that happened to me and we developed the habit of regular mutual visits. After a while, our research interests that had diverged for a few years, serendipitously also came together again. This continued until Hans retired from his position at the University of Nijmegen, late in the summer of 1991, at the age of 54.
The direct occasion for this very early retirement was the fact that his highly skilled animal caretaker, Anton Buijs, with whom he had worked for over 25 years, was retiring and that the University of Nijmegen had decided not to provide a replacement. This unfortunate decision was part of a pattern of lack of support for Hans' work, that he had to suffer throughout his career. This attitude of the Dutch research establishment was the more curious, given the wide recognition that Hans' work received from abroad.
Hans started his career as a Ph.D. student of Prof. S.J. Geerts. One of the first great events of that period was the organization of the Twelfth International Congress of Genetics, which was held in 1963 in The Hague, The Netherlands. Geerts was the scientific secretary of this Congress and Hans assisted him with the organization. As such, he met with many of the most famous 20th century geneticists, such as J.B.S. Haldane. It was here, too, that he met Jerry McClearn, with whom he shared a keen interest in the budding field of behaviour genetics. At this meeting, Hans presented some of his work on behavioural differences between mice carrying different mutations, that would lead to his doctoral dissertation . In his dissertation, Hans remarked that the behavioural effects that he observed, might be due either directly to the mutations studied, or to genes closely linked to them. In his later research he more or less abandoned this approach, because it rapidly became clear to him that it would not lead to important advances in our understanding of the genetic regulation of behaviour. It is interesting to note that this type of research has recently been taken up again in the form of Quantitative Trait Loci analyses.
Immediately after obtaining his Ph.D., Hans left for The Jackson Laboratory (TJL; Bar Harbor, ME, USA) where he spent one year to do postdoctoral research. This was a formative period, in which he established contacts with many of the leading mouse geneticists of that time, many of them working at or passing by TJL. Among them were Earl Green (then director of TJL), Thomas Roderick, and Dick and Cynthia Wimer, to name but a few. It was also at TJL that Hans became interested in pharmacogenetics. His thorough way of delving into problems is perhaps best illustrated by his careful analysis of the possible effects of saline injections on behaviour, which was reported in a tiny article in Psychological Reports . This article also demonstrates his aversion of wordiness and continuous striving to report data as succinctly as possible. Upon returning to Nijmegen, Hans obtained a faculty position in the Laboratory of Genetics headed by Prof. Geerts.
Hans was not only one of the first to study pharmacogenetics, he was also one of the very few that saw how strain differences in reactions to pharmacological treatments could be used to further our understanding of the underlying mechanisms. All too often, even nowadays, researchers content themselves to describing such strain differences and then concluding that "strain-treatment" or "genotype-treatment" interactions exist. Hans clearly saw that such a "conclusion" is nothing more than a simple description of the data and does not add anything to our scientific understanding. His interest was not just providing a description of inheritance patterns of treatment effects, but rather the neuronal mechanisms underlying such effects. In this respect he was a true behavioural neurogeneticist and, together with scientists like the Wimers, Hans was one of the founders of our discipline. Indeed, in 1970 he was one of the founding members of the Behavior Genetics Association, of which he remained a member until 1995. In addition, he served as a member of the Editorial Board of Behavior Genetics from its creation in 1971 until early 1992.
In that period, he also started a selective breeding program. Starting from an F2 generation between the inbred strains C57BL/6J and DBA/2J, Hans selected bidirectionally for rearing frequency in male mice exploring an open field. One innovative step that he introduced in the selection design was that during the first five generations of selection, selected males were backcrossed to inbred DBA/2J females. In later generations, selection was combined with inbreeding through sib-mating. The objective was to transfer one or a few of the polygenes influencing this behaviour from C57BL/6J onto a DBA/2J background. This procedure resulted in two inbred lines (which nowadays we would probably call selected recombinant congenics) SRH and SRL (Selection for Rearing High and Selection for Rearing Low, respectively), whose difference in their rearing frequency is most probably related to one single gene only *. Using these two lines, together with their progenitor strains, Hans was able to show that the low rearing frequencies exhibited by SRL and DBA/2J are due to unbalanced neurotransmitter systems in the hippocampus. The idea that DBA/2 has a malfunctioning hippocampus has been taken up again in the last decade, almost 20 years after Hans' initial results were first published. His series of careful, step-by-step experiments, employing C57BL/6J and DBA/2J and his SRH and SRL animals, should be required reading for any behavioural neurogeneticist.
Despite the productivity of this period, not all was well. Prof. Geerts had left the Dept. of Genetics at the Faculty of Science to become Chair of the Dept. of Anthropogenetics in the Faculty of Medicine and relations between Hans and Geerts' successor, Prof. H.D. Berendes, were less than cordial. For this reason, Hans left the Dept. of Genetics and joined the newly formed Dept. of Animal Physiology under the new Chair, Prof. A.P. van Overbeeke. Bram van Overbeeke clearly realized the calibre of the scientist that joined his Department and gave Hans the room he needed to continue his research program. The catastrophic stroke that Bram suffered in the late eighties and that left him completely aphasic was not only dramatic for Bram and his family, it was also the beginning of the end of Hans' scientific career. Van Overbeeke's successor clearly lacked the insight of his predecessor: he once even confided to me that he would like Hans "to develop into a researcher of national stature"! All that this accomplished was to turn gold into lead, when Hans decided that this was not the way he wanted to end his career. His early retirement and the lack of support from national research organizations throughout his career are sad testimony to the state of our discipline in The Netherlands.
In the seven years that were given Hans after his retirement, he pursued several life-long interests: travel, music (especially Wolfgang Amadé Mozart), and the human mind. Despite leaving the field, he kept a keen interest into its development and he was one of the first to become a founding member of IBANGS (then EBANGS) in 1996. Throughout this period, we stayed in close personal contact. As said before, Hans had a warm personality and a strong interest in people. This trait also was at the root of what some people regarded as his greatest "defect" (although I would rather term it a quality): a fundamental inability to believe that stupid, or even evil persons could exist. When confronted with stupidity, Hans never ceased to try to convince his adversary of the wrongness of his ways, stubbornly holding to the belief that this person was only mistaken, and basically good. Of course, to his deep frustration and disappointment he failed in this quite regularly and the fundamental inability of some people to think (and act) rationally remained a complete enigma to him.
The past year and a half have shown painfully the importance to me of Hans' opinions and advice. Meeting him back in 1974 changed the course of my life and it was a privilege to have had him as teacher and mentor. I will continue to sorely miss his friendship.
Hans is survived by his wife Janny, his three daughters from a previous marriage, Daphne, Edith, and Iris, and his grand-daughter, Isa.
Wim E. Crusio
Orléans, June 1, 2000
*The inbred selected lines SRH and SRL are still in existence and have now undergone more than 80 generations of inbreeding. Breeding pairs are available upon request by emailing Wim E. Crusio.
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