Tribute to Michael Land, 1942 - 2020

Mike gave me my first 'sort of proper' job - as a temporary lecturer at Sussex. Or rather Mike waved his hands in that characteristic circular way and with a guffaw decided it,  just like that. The neurobiology group was looking for someone to fill Ian Russell's research leave and I had met Mike  again couple of years earlier in Berkeley where he was giving an evening talk on jumping spiders. It had terrific throwaway lines. The Sussex position was my third bounce through the place  - I'd been originally an undergraduate there and then again  trying to learn biology  in the early 70s. Mike's enthusiasms were memorably infectious: he came bounding along the corridor onbe day to say he and Tom Collett had at last filmed hoverflies flying sideways. As a family we ended up in a cottage down from Lewes owned by the wonderful Marjorie Abrahams. When Mike went to Canberra for a year he lent us his sailing boat on Piddinghoe Pond, a small circular patch of water on the way to Newhaven,  with a clubhouse and a Commodore to control the waters (and the clubhouse). I never learnt to sail - even across the pond - and hope that the boat survived by the time he got back. But by that time I had left Sussex with no further opportunity to work with Mike other than write a ray tracing program which showed how parabolic lens could be better than a spherical one.  I did however manage to get him elected as a Fellow of UCL:  small payback, but at least he got one posh dinner out of the evening.

Mike was my undergraduate Tutor in Biols from 77 to 80. I'll always remember his light touch guidance, wisdom and inspiration. What a privilege it is to have had his attention, I just wish I'd realised that at the time. It was he who showed that we can only truly understand something if we can model it with working kit. However, trying to write a program in C on the Labs PDP-8 to model the catching of a Frisbee was a triumph of hope over experience for me. Sadly, we will not see his like again. I wish I'd known him better. RIP

In the early 1980’s Sussex University had a Thatcher-induced financial crisis. Anyone who could remove themselves from the payroll for a couple of years was regarded as a hero. Luckily this coincided with my getting a two-year fellowships at the Australian National University in Canberra, where once again, there was a remarkable coincidence of interesting eye people, including Simon Laughlin, Dan-Eric Nilsson, Daniel Osorio, Joe Howard, David Blest, Eldon Ball and not least my host, Adrian Horridge. A number of us tried to sort out the optics of butterfly eyes, the issue being that butterflies have apposition eyes but their close relative the moths mostly have superposition eyes. How could one type evolve into the other? Dan-Nilsson cracked this by discovering in the bottom of the butterfly crystalline cone a tine lens of immense power (0.2 megadioptres!) which brought the butterfly and the moth structures into line anatomically, but provided the former with apposition-like optics.

After I returned to England I had a new research student, Justin Marshall, who shared my enthusiasm for mantis shrimps – vicious crustaceans with amazing eyes. Within a year or so he had discovered, with Tom Cronin, that they have a colour-vision system based on 9 visual pigments – now extended to 12 as it transpired that they have another 4 in the ultra-violet. They have funny eye movements too, which is where I came in, but it is the colour vision that is so astonishing.

Since about 1990 much of my research has been on human eye movements. About that time I invented a video-based, head-mounted monitor that left the wearer completely free to do ordinary things. The secret was to leave the computation of eye-direction until after the activity was finished, thereby making the device itself very light. So far we have used this system to study driving, playing ball games and sight reading music. Our ethological colleagues would like to take it to a disco to study mate choice, but so far we have resisted this. The questions of interest revolve around the way we sample the world, given that our region on acute vision is only about 1 degree across. Where do we need to look to get the information we need to do things? Answers are emerging, but we get into trouble with some of our psychologist colleagues. “But this is only curiosity driven” they say. “Where are the hypotheses?” The trouble with hypothesis-driven is that you never get to make a discovery. And that’s the real buzz.

My interest in biology seems to have come from a childish desire to collect, which in my case took the form of squashing half the British flora. By my mid-teens the immobility of plants began to bore me, and I switched to zoology when I went to Cambridge. In those days (ca. 1960) the sex ratio in Cambridge was so dire as to preclude normal life, but the resulting monastic existence did mean I got a decent degree. Among my teachers there I would single out Carl Pantin, the professor of Zoology. His course on the Invertebrates – a mixture of taxonomy, anatomy, physiology, ecology and behaviour – left me with a life-long enthusiasm for the seafood end of the animal kingdom. It helped that there was a good museum in the department, where I developed a kind of nineteenth century naturalist’s fascination for the more bizarre products of natural selection.

After Cambridge I went to do a PhD at University College London, where I worked on the eyes of scallops and finally enjoyed some female company. I had persuaded my supervisor, John Gray (later to become secretary of the Medical Research Council and ultimately Sir John) that scallops had a nice ganglion that all these eyes fed into, and a clear – if dull- behaviour (shutting), and that this ganglion clearly needed its input/output relationships sorting out. In fact I didn’t get past the eye. Quite early on I made a chance observation that when one looks into a scallop’s eye, one sees an inverted image of oneself. At first I thought, fine, all eyes have images, but then in eyes like ours the image, as viewed through the lens, isn’t in the eye itself, but back where the object was – somewhere near infinity. Scallops’ eyes turned out to be unique; the image was indeed not formed by a lens, but by the reflecting mirror that lined the back. This was a great stroke of luck. A nicely identifiable discovery that made me think “hey, I can do this science stuff”, and I haven’t really looked back.

After London, to Berkeley, on a Miller fellowship sponsored by Gerald Westheimer, who taught me about eye movements and magic optical arrangements such as the Maxwellian view, and Dick Eakin, who by then had looked at the ultrastructure of the eyes of just about everything. As the Chinese curse has it: “May you live in interesting times”. Berkeley in the late 60’s was certainly interesting. We had Eldridge Cleaver and the black panthers, people’s park, the Alameda County Sherriff’s deputies and finally the National Guard, with the Vietnam war in the background as the engine for much of the unrest. At the same time there was a wonderful gathering of eye people. Apart from my sponsors, Horace Barlow, Jack Pettigrew, Colin Blakemore and Bill Levick were there, as were Barry Frost, Ron Hoy and several other human physiologists. After one or two false starts I decided to work on jumping spiders, inspired by some remarkable work on their vision by Heinrich Homann in the 1920’s and set about collecting them by bashing branches of trees into an umbrella earning me a reputation as a harmless lunatic. Jumping spiders have movable principal eyes, and my most interesting discovery from that era was that when a spider sees a small moving target the eyes go into a very repeatable scanning routine involving both side to side and torsional movements of the retina. At least one function of this scanning routine was suggested already; it permitted the spider to make the distinction between objects that were edible and others that it would be more appropriate to mate. Oscar Drees had shown in the 1950’s that spiders really like legs: enough legs at the right angle and a male jumping spider will start his highland-fling-like mating dance.

I returned to England in 1971, to a temporary post in the University of Sussex, a new and attractive campus that had managed to get most  of its buildings completed before the money ran out in the mid 1970’s. My first collaborations were with Tom Collett, on the ways flies chase each other, based on the observation that flies under lampshades seemed to go in for small-scale Snoopy and the Red Baron dog-fights, and if this was the case there would have to be appropriate control systems involved (I had earlier read some of Horst Mittelstaedt’s papers and become quite interested in control theory). Switching from houseflies to hoverflies Tom and I were particularly impressed by the similarities of some hoverfly behaviours to human eye movements – the saccades, tracking, optokinetic stabilizing, etc – except of course that these were brought about by flight manoeuvres not eye muscles. The thought that much behaviour, especially in insects, is to be explained as subserving the active uptake of visual information, is an idea that has remained with me ever since. Tom and I also looked at visual memory in hoverflies, and he developed ideas that were to lead to the celebrated “snapshot model” of bee landmark memory that he and Brian Cartwright developed in 1982.

Meanwhile, I had deserted behaviour, temporarily, and returned to optics. I was lucky enough to have a friend, Peter Herring, who organised deep sea cruises on the RRS Discovery, and I went on 4 of these altogether. In 1975 I found that shrimp eyes work on a mirror mechanism, in which an array of corner reflector boxes, at right angles to the cornea, form a superposition image on the retina. Later I found out that I was only the belated co-discoverer of this system; Klaus Vogt, then in Tübingen, had found the same mechanism in crayfish the year before. Still, by then I had already had my celebratory drink! Subsequently this mechanism turned out to be useful for focussing X-rays (for telescopes) and collimating them (for sub-micron circuit etching). It was satisfying to see biology leading engineering, for a change. There were many other good things in the sea: the spectacular double eyes of hyperiid amphipods and euphausiids, the scanning eyes of heteropod molluscs, and the strange eyes of pontellid copepods – each using a different optical principle. Sadly, going to sea now involves a lengthy bureaucratic hassle – in the old days Peter simple called me on the phone.

For Mike,

A trip through memory lane is not always sheer pleasure, because that lane is not only fringed by many flowering shrubs, but there are also several parts sided by trees with dark shades. It therefore has taken me some effort to walk through it again, being filled with the sad feelings caused by the loss of Mike.
            I first heard about Mike during a visit as a student to Tübingen (1973), then a famous centre of insect vision research, packed with very expensive, sophisticated experimental equipment: this guy from England had analysed the visually-guided behaviour of flies with a miserable glue-and-rubber-band approach and had still been able to gain far-reaching insights; how embarrassing! Of course, I started to follow Mike’s publications. Later, in 1979 on vacation in England with my wife Jeannette and our young kids, I took the opportunity to visit Lewes. The boys much appreciated the company of Adam. We stayed a few days longer than planned, because Mike and I, joined by Jochen Zeil, then Mike’s student, not only had much to discuss about the optics of insect eyes, but also fueled our discussion with booze. They taught me many things, notably that their ability to avoid the alcohol diffraction limit was much better than mine. Since then, we maintained regular contact, among others during meetings in Regensburg (Germany), Sherbrooke (Canada), in Sussex, various places in England, and when he visited Groningen. Of those occasions I add a few pictures. When in Sussex, I had the great pleasure to be lodged comfortably and with great hospitality by the Land family.     
            Mike has been a most significant scientist. He has inspired numerous workers in the field, including myself, both by his profound insight that he shared in his books and many lucid papers and reviews, and by his exemplary tendency to devise effective and simple setups and analyses. This sometimes became almost a matter of a conflicting way of doing science. As an example, when I developed a rather detailed and complicated analysis of fly eye optics, Mike’s response was humbling: why can’t you give us a simple formula, so that we can really understand what is going on. I couldn’t comply nor disagree. The difference between continental and British approaches has a long tradition, however I should note that Mike also inspired the famous A.F. Huxley to publish a rather involved theoretical treatment of optical multilayers (JEB, 1968).
              I will often feel that we no longer can witness Mike’s sharp intellect, his witty and often pointed remarks, as well as his amiable and charismatic personality.

Groningen, January 20, 2021                                                  Doekele Stavenga