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Guest post by Ferdinando Boero

Check out the discipline of ‘Biochemistry and Molecular Biology’ in the Journal of Citation Reports (JCR) and rank the 286 journals based on the impact factor (IF). The IFs of the top ten journals range from 32 to 10. Now sort them by cited half life (CHL), a measure of how long a paper continues to be cited: 27 journals (9% of the total) have a CHL >10, a reference point of ‘infinity’ for JCR, which is positive indeed. Looking at these 27 journals, and omitting reviews, their IFs range from 8 to 0, and most are <5. Now take Zoology. The IFs for these top 10 journals range from 4 to 2, in a list of 145 journals. In this comparison, the chemical approach to biology reigns victorious. Now rank zoology journals by CHL: 57 (39%) of them score >10, with IFs of those journals ranging from 4 to 0. In this scenario, zoology beats molecular biology 57 to 27 or, even better, 39% against 9%. The upshot is that, if you publish a paper in zoology, it will live much longer than a paper in biochemistry and molecular biology – with the majority of the golden papers in the latter discipline rapidly decaying into oblivion.

Is it better to have a high IF and a low CHL or vice versa? Of course, it would be better to have both scores high, but usually this does not happen. Indeed, the journals with high CHL in biochemistry and molecular biology have low IF). One might object: is it right or even relevant to ask what is better? My answer is no, but this is currently how the relevance of science and its funding, not to mention career opportunities, are determined. As a consequence, zoology is disappearing (especially the subdiscipline of taxonomy; see E.O. Wilson’s essay in October’s 25th anniversary issue of The Scientist), whereas molecular approaches are paramount. Why? If you publish in zoological journals, your scientific impact as measured by the IF is low, whereas if you pursue a molecular approach, your impact is high, at least for the moment.

Why not mediate the metrics based on a combined IF and CHL? Unfortunately, zoologists do not even know what CHL is. So instead of playing the CHL card and holding their ground, zoologists are determined to join the game of molecular biologists, with molecular taxonomy now triumphing over traditional approaches.

Scientists are evaluated throughout the world based on the IF of the tribunes where they publish their work. The higher the IF and the H (Hirsch) index, the better the scientist – or so the common wisdom goes. The CHL is ignored. I propose the Boero index: multiply the IF by the CHL. With ‘infinity’ as one of the multipliers, the results can be absurd: a glorious 57 infinities in zoology with a mere 27 in biochemistry and molecular biology. This absurdity merely highlights the need to be more objective while ranking scientific disciplines and the researchers who practice them. Taxonomy is dying because of the low IF of taxonomic journals. Is this right, especially now, in the era of dramatically diminishing biodiversity?

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Ferdinando Boero is Professor of Zoology at the Department of Biological and Environmental Sciences and Technologies of the University of Salento, Lecce, Italy. He is an F1000 Faculty Member in the Ecology Faculty.