Teachers notes - Lord Robert May

Physicist and ecologist


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This interview is also available in full on the Australian Academy of Science's youtube channel.
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Lord Robert McCredie May was interviewed in 2011 for the Interviews with Australian scientists series. By viewing the interviews in this series or reading the transcripts and extracts, your students can begin to appreciate Australia's contribution to the growth of scientific knowledge and view science as a human endeavour. These interviews specifically tie into the Australian Curriculum strand ‘Science as a human endeavour’ and its two sub-strands ‘Nature and development of science’ and ‘Use and influence of science’.

The following summary of Lord May’s career sets the context for the extract chosen for these teachers’ notes. The extract discusses his ‘accidental’ transition from physicist to ecologist, and how mathematics allowed him to devise one of the most important theoretical milestones in ecology. Use the focus questions that accompany the extract to promote discussion among your students.

Summary of career

Lord Robert McCredie May of Oxford, OM AC Kt FRS was born on 8 January 1936, in Sydney, Australia. He attended Sydney Boys High School and studied chemical engineering and science at Sydney University. After receiving a PhD in physics from Sydney University in 1959 his academic career included a personal chair in physics at Sydney University aged 33, Class of 1877 Professor of Zoology and chairman of the research board at Princeton, USA, and Royal Society Research Professor in Oxford University, UK.

Lord May was Chief Scientific Adviser to the UK Government and Head of the UK Office of Science and Technology (1995-2000) and President of The Royal Society (2000-2005). He is a member of the UK Government’s Climate Change Committee, a Non-Executive Director of the UK Defence Science & Technology Laboratories and Chaired the Trustees of the Natural History Museum. His research interests include how populations are structured and respond to change, particularly with respect to infectious diseases and biodiversity, and the structure and dynamics of ecosystems.

May was awarded a knighthood in 1996, and appointed a Companion of the Order of Australia in 1998, both for ‘Services to science’. In 2002 he was the seventh Australian in 100 years to be appointed to the Order of Merit by the Queen. His many honours include: the Royal Swedish Academy’s Crafoord Prize (bioscience and ecology’s equivalent of a Nobel Prize); the Swiss-Italian Balzan Prize (for ‘seminal contributions to biodiversity’); and the Japanese Blue Planet Prize (‘for developing fundamental tools for ecological conservation planning’). He is a Foreign Member of the US National Academy of Sciences, an Overseas Fellow of the Australian Academy of Science, and an Honorary Fellow of the Royal Academy of Engineering and several other Academies and Learned Societies in the UK, USA and Australia. In 2007 he received the Royal Society’s Copley Medal its oldest (1731) and most prestigious award, given annually for ‘outstanding achievements in research in any branch of science’.

Lord May is presently Professor at Oxford University and Fellow of Merton College, Oxford.

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Extract from interview

Accidental ecologist

You have written so many seminal papers. Which was the very first that made the mark?

It wasn’t any of the things that I did in physics, although I did do one or two cute things. My favourite is the first thing I ever did in physics, which was in my first year as a graduate student. This thing is really rather startling although it was completely uninteresting until very recently. At morning coffee at Sydney, somebody mentioned, ‘You know, there can’t be two-dimensional superconductors, because the two-dimensional Bose gas doesn’t condense, and that is a critical phenomenon for getting superconductivity’. I thought, ‘That’s amusing. I’ll have a look at that’. I went home and I discovered that, indeed, it didn’t condense. But it only just didn’t and you couldn’t tell the difference. I came back and told my supervisor Robbie Schafroth this, and he was interested. I also told Pauli.

Then I thought more generally about two-dimensional ideal gases and I proved an amazing and wonderful theorem. It is not very interesting but really cute. In two dimensions, the specific heat of a two-dimensional Fermi gas is identical as a function of temperature with the ideal Bose gas. This is crazy, because the specific heat is determined by just the surface electrons in a Fermi gas and by everything in a Bose gas. But it is true and it is now an exercise in books. Now that we have two-dimensional grapheme, maybe you can actually do an elegant experimental check. I have talked to the people at Manchester about this. But I would never have got elected to the Royal Society for what I did in physics.

A few years after I returned from Harvard to Sydney, I accidentally got interested in problems in ecology. This was very much encouraged by Harry Messel. He said, ‘If you want to do that, by all means stay in the physics department. If you want to go somewhere else, you should do it’. But Harry had been telling me for quite a few years when I came back that I ought to get into bringing physics into biology. So he was very pleased when I did. The first thing I did in ecology is one of the most important things I have done.

What’s that?

Charles Birch was head of biology at Sydney and a wonderful man. He was one of the founders of Social Responsibility in Science in Australia, and involved in all these “1998 things”. Also, in the Vietnam War, he was a willing source of counselling for people who wanted to not be caught up in it – in a very un-ego-gratifying way. In discovering what I was being conscience stricken and socially responsible about, I read a book by Ken Watt on “Ecology and Resource Management”. In it, was a clear articulation of an emerging theoretical notion in ecology. You have got to understand that ecology is a very young discipline. The word is only 100 years old. The oldest professional society, the British Ecological Society, is just about to celebrate its centenary. Its first half century was largely descriptive but with a little bit of theory.

At that time there was a belief articulated by one of the founding fathers of theoretical ecology, Evelyn Hutchinson at Yale. He was building on ideas by Elton and later work by Robert MacArthur at Princeton. The idea was that complicated ecosystems – ecosystems with more species and more interactions among them – would, by virtue of that complexity, be more stable. Hutchinson had formally asserted this as one of the fundamental principles. Ken Watt set that out. Then, very commonsensically, he said, ‘It’s pretty contrary to common experience’. As I read that that evening, I said, ‘Actually that’s right’. Elton gave a series of arguments. One was that mathematical models for two-species systems are characteristically unstable. I thought, ‘That’s not an argument. That’s only half an argument. Let me look at not “one predator one prey”. Let me look at “N predator N prey” ’. I immediately could see that the corresponding system would be less stable.

To cut a long story short, I proved a rather nice theorem. That is, a generalisation of a physics theorem due to Wigner. I am delighted that my name is now coupled – it is the May-Wigner theorem. He proved it for special kinds of symmetrical matrices. But I said, ‘Let’s imagine an ecosystem in which each species by itself would be stable. So, I’ll put minus one down the diagonal to say that in unit time, left alone, each species would recover from a disturbance. Now I’ll start connecting them at random and putting other elements in the matrix. I’ll put plus or minus to give predator-prey, competitors or mutualists. I’ll let them be of different strengths but, on average, some strength – let’s call it alpha’. I proved an interesting generalisation of Wigner’s theorem that said: ‘Such a system will remain stable, stabilised by the intraspecific effects, provided that the average number of species a species is connected to, times the square on the strength, is less than one. One is the normalising time to recover. Otherwise the system will collapse, if “N” is big’. That turns the whole thing on its head and resets the agenda for ecology. I was connecting at random, and ecosystems are the winnowed product of evolution and are not random. So it says: ‘In the real world we see a lot of complicated systems. What are the special, non-random structures that they have, to reconcile exploiting more niches, having more species and being more complicated, with robustness against disturbance?’ We are still working on that, although we have made a lot of progress, particularly with the experimentalists. That was the first thing I did, which was one of the most important, the centrepiece of the monograph on “Stability and complexity in model ecosystems”.

The implication of your theorem is that, if you have a very big, complex population and you reduce it, even if it’s the loss of little creatures you can’t see or elements that you don’t take any notice of, if you reduce it too much, the whole system can break down.

According to what I’m saying, you don’t know what’s going to happen! There has been a lot of subsequent work by some very able younger people too. There are interesting things going on as we speak. But yes, that is a good one sentence summary.

What was Charles Birch’s reaction to that?

When I had this insight about stability and complexity, I immediately went to Charles Birch because he was the co-author of what was then the world-leading text on ecology – Andrewartha and Birch. But he identified with the view that there is no place for mathematics in ecology – it is all about looking at nature. The wonderful thing about Charles was that I told him what I had done and he said, ‘You know that I think mathematics doesn’t have much to say about ecology, but who knows who’s right? My friend Ken Watt, whose book you’ve just read, would really love that. You write it up and send it to him and come and give a seminar in biology’. So I did all that and I had a nice letter from Ken Watt, who wrote ‘this is a milestone in ecology’.

An edited transcript of the full interview can be found here.

Lord May’s full interview is also available on the Australian Academy of Science’s YouTube channel.

Focus questions
The following questions involve ecology, which was Lord May’s second career focus. Some references to activities in physics are provided further below.

Students may need access to a science reference book, dictionary or the internet to answer some of these questions. In his interview Lord May speaks about his proposal for a new theorem that investigated stability and complexity in ecosystems. Professor Robyn Williams summarised it as: if we take a very big, complex population and substantially reduce it, the whole system can break down. After reading this section of his interview and/or watching it on the Academy’s YouTube Channel,

  • Break into small groups and complete the following tasks.
    • What is an ecosystem?
    • Choose an example of a large ecosystem. Use textbooks and/or the internet to list at least 20 examples of different plants and animals that occupy that particular ecosystem. Include large and microscopic examples in your answer.
    • Briefly describe each of your examples. This could include drawing a simple picture to show its shape and colour, its size, where it lives and what it needs to survive, grow and reproduce.
    • On a whiteboard or large piece of butcher paper, draw a large schematic of your ecosystem which includes all the different examples that you listed above. Draw in other things that are needed for your ecosystem to remain healthy, such as water, soil, rocks and sunlight. Use red arrows to show how the various plants and animals in your example are linked together. (For instance, you could show a link between a plant and a fish that eats that plant). Use black arrows to show the links between the living and non-living parts of your ecosystem. (For example, between a green photosynthesising plant and the sun).
    • Take it in turns talking about the kinds of disturbances that may affect this ecosystem. You could discuss how these disturbances are brought about, which parts of the ecosystem are directly affected, which parts of the ecosystem are indirectly affected (use your schematic diagram to help with this) and whether you think the effects of these disturbances can be easily reversed.
    • Present your work to the class as a group. Conclude by describing the main things that you think are needed to keep this ecosystem healthy and some of the greatest disturbance threats to its future survival.

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Select activities that are most appropriate for your lesson plan or add your own. These activities align with the Australian Curriculum strands ‘Science Understanding’, ‘Science as a Human Endeavour’ and ‘Science Inquiry Skills’, as well as the New South Wales syllabus stage 6 aenior science outcome 9.3.1 and stage 6 biology outcome 9.5.6. You can also encourage students to identify key issues in the preceding extract and devise their own questions or topics for discussion.

• Related interviews from the Australian Academy of Science

  • Professor Hugh Possingham
    Professor Birch (ecologist) was head of biology at Sydney, a co-author of leading textbooks in ecology and one of the founders of Social Responsibility in Science in Australia. May shared his insight into stability and complexity in ecological systems with Birch because at the time he was one of the co-authors of one of the leading textbooks in ecology. Birch pointed May in the direction of other leading ecologists who hailed May’s insight as a milestone in ecology.
  • Charles Birch.
    Professor Slayter (ecologist) was Australian Chief Scientist and foundation professor in environmental biology in the Research School of Biological Sciences at the Australian National University. One of his research strengths was ecological succession in disturbed ecosystems. He tried unsuccessfully to convince Lord May to study ecology in Canberra.
  • Professor Ralph Slayter
    Professor Slayter (ecologist) was Australian Chief Scientist and foundation professor in environmental biology in the Research School of Biological Sciences at the Australian National University. One of his research strengths was ecological succession in disturbed ecosystems. He tried unsuccessfully to convince Lord May to study ecology in Canberra.
  • Professor Hugh Possingham
    Professor Possingham (mathematical ecologist) has done pioneering work on the viability of populations of endangered species and the application of decision theory to conservation biology. His research has included the application of mathematical and computational tools to understanding ecological systems.
  • Interviews with Australian Physical Scientists
    This full range of physical scientist interviews includes teacher’s notes and links to activities in areas such as general physics, nuclear physics, geophysics and theoretical physics.
  • Interviews with Australian Environmental Scientists 
    Includes transcripts of the full interviews with teacher’s notes and activities.

Other activities

August 2010

The Science of Climate Change: Question and Answers
A document summarising the current understanding of climate change science for non-specialist readers.

Nova – Science in the news
The following Nova – Science in the news topics involve ecology and biodiversity. They include key text extra reading and links, student activities and a detailed glossary.

The following Nova – Science in the news topics involve physical science and complex systems. They include key text extra reading and links, student activities and a detailed glossary.

Primary Connections – Schoolyard safari.
This Australian Academy of Science education program is fully aligned to the Australian science curriculum. Students explore small animals leading to a better understanding of how their adaptations help them survive in their habitats. Through investigations, students learn how animals move, feed and protect themselves.

Biodiversity and nature – student  activities (Collated by the NSW Department of Environment and Heritage)
Includes links to a range of ecological activities, information, games, animations and resources.

Raptor population ecology (Seaworld)
In this activity students calculate population size, carrying capacity, annual change in population size, and the maximum rate of population increase in a raptor colony.

Introducing biodiversity (American Association for the Advancement of Science)
Lessons and online resources for teaching students about the basic components necessary for biodiversity, the benefits of habitats, and the present and future threats to their ongoing existence.

Population ecology worksheet  (Population connection)
Explores how annual growth and seasonal fluctuations are measured in natural populations. This activity also discusses similar growth patterns in other areas, such as commerce (which was another area to which Lord May later adapted his ecological theorem).

Oh dear! (Project wild)
A student activity that discusses habitat, limiting factors in population biology, predator/prey influences, and other factors that affect ecosystems.

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population dynamics
complex systems

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