Acceptance Speech – Rome, 23.11.1998


Robert McCredie May

1998 Balzan Prize for Biodiversity

For his seminal contributions to the mathematical analysis of biodiversity, in particular, his pioneering work on chaos theory and ecological systems, and the development of a variety of methods for estimating the total number and rates of extinction of species living on the earth today.

Balzan Prize Awards Ceremony 1998
Rome, Accademia dei Lincei, 23 November 1998

Mr. President,
Members of the Balzan Foundation,
Ladies and Gentiemen,

I am delighted that the International Balzan Foundation chose the important subject of Biodiversity in 1998, and deeply honoured that it has awarded me the consequent Balzan Prize, am also very aware that receive this Prize as a symbolic representative of the large community of scientists many of them friends and colleagues — who in recent years have greatly advanced our understanding of the causes and consequences of biological diversity.

Biodiversity is a newly coined word, which stands for the study of Nature’s riches at many levels, from genetic diversity (the raw stuff upon which evolutionary processes work) through to the diversity of our planet’s ecosystems. In particular, Biodiversity research asks questions about how many species are alive today, at what rate extinctions of plant and animal species are speeding up, and why we should care about the loss of Biodiversity.

I first became interested in the field of Ecology and Biodiversity in the early 1970s. This was a particularly interesting time in the history of the subject. Previously, researches in this area had laid foundations which were largely descriptive and observational. In the third quarter of this century, led by people like Evelyn Hutchinson and Robert Mac Arthur (themselves drawing on earlier work by the great Italian mathematician Vito Volterra and others), central questions were beginning to be asked in more analytic, even physics-like, terms. How does the structure of the web of interactions among species affect the communities’ ability to recover from disturbance or to resist invasion? What factors determine the observed variety of patterns of species abundance, of commonness and rarity? Why are there roughly 700 species of breeding birds in North America, and around 200 in Britain, and more generally what determines species numbers in different places? Ultimately, what are the causes and consequences of biological diversity? By happy accident, I brought the analytic skills of a theoretical physicist — trained at Sydney University by the Swiss Robert Schafroth, who was Wolfgang Pauli’s last Assistant at Zurich —to these problems at just the right time.

In collaboration with many other people, this work has led, amongst other things, to various ways of estimating the number of plant and animal species alive on earth today, which I would guess to be in the range 5 to 15 million. This contrasts with the 1.5 million distinct species named and recorded, which number is itself uncertain to within 10%, because we still lack central databases for most species. Although the International Union for the Conservation of Nature and others ore making a good start, we need more resources devoted to the basic task of co-ordinating the taxonomic information we have, and to devising new and imaginative ways of speeding up rates of identification of the yet unknown.

Other analytic approaches suggest that current rates of species’ extinction run around one thousand times the average rates seen in the fossil record, and are likely further to accelerate over the next century. This puts us on the breaking tip of a sixth great wave of extinction in the history of life on earth. One sad consequence is that we will increasingly need new approaches to choosing which species to try to save; a “calculus of biodiversity” for making agonising choices.
I believe these are matters of concern far all of us. But effective action must be based on good scientific understanding of the underlying causes, and likely consequences, of Biodiversity loss. So I am hugely pleased to accept the Balzan Prize for Biodiversity in recognition of the vital importance of the subject.

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