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How inbreeding affects productivity in Europe


Navarro and Rivero in Correspondence1 for the first time quantified favouritism (“inbreeding”) in Spanish universities, showing that it is at least 10 times higher than in France, the United States and the United Kingdom. I have now quantified this phenomenon in 51 universities from 14 European countries.

I examined the relationship between the percentage of papers published by each country and its level of inbreeding. I gathered information from 51 ecology or zoology departments via a brief questionnaire requesting information on the number and rank of teaching positions, as well as the number of these staff trained at the same university. I obtained responses from at least two universities in each country. I estimated “inbreeding” as the percentage of staff in these positions trained at the university. I found significantly more variance in inbreeding among than within countries (F = 12.38, d.f. = 13, 37, P < 0.0000001; one-way analysis of variance), showing that countries are consistent in their degree of favouritism.

Spain registered the second highest level of inbreeding, averaging 88%, surpassed only by Portugal (91%). Figures for the remainder are (in %): Italy (78), Austria (73), France (65), Norway (56), Belgium (52), Finland (48), Netherlands (40), Denmark (39), Sweden (32), Switzerland (23), United Kingdom (5.2) and Germany (1).

To explore the relationship between level of inbreeding and scientific productivity, I used May's enlightening report2, in which he assesses the quality of the contribution of various countries to world scientific knowledge. May provides information about the share of papers and citations in science, medicine and engineering provided by 15 countries, not including Portugal, Spain, Austria, Norway and Belgium. If, conservatively, I assign these countries a value of 0.5, a significantly negative correlation appears between the percentage of papers published by each country and its level of inbreeding (Rs = −0.60, P = 0.02, n = 14). That is, overall scientific productivity correlates negatively with the percentage of inbreeding.

In the 1980s the Spanish government attempted to end inbreeding in its universities by the University Reform Law (LRU). The Real Decreto 1888/1984 of 26 September, which regulates the employment system in Spanish universities, clearly states: “The research activities of the candidates shall be evaluated as the priority merit” (Art. 8.2.a). This reform has, however, failed to change the system3; indeed, the problem has become even more serious, as pointed out in two Nature editorials4,5.

The inbreeding system is extremely stable. The solution needs vigorous measures: first, every position should be advertised internationally; second, there should be no local members on appointment committees; and third, lecturers or full professors with low scientific productivity should not serve on committees that appoint professorships. As things stand, Spanish universities are autonomous and they do not want the system to change because, in general, university politicians (people who manage universities) are not good researchers and do not consider that scientific productivity is paramount.

When will the Spanish government decide to implement the necessary drastic reforms?


  1. 1

    Navarro, A. & Rivero, A. Nature 410, 14 (2001).

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  2. 2

    May, R. M. Science 275, 793–796 (1997).

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  3. 3

    Rodilla, V. Nature 376, 290 (1997).

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  4. 4

    Nature 389, 767 (1997).

  5. 5

    Nature 396, 709 (1998).

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Soler, M. How inbreeding affects productivity in Europe. Nature 411, 132 (2001).

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