NEWS AND VIEWS within the oceanic plates. Yet the plates would produce 100 per cent strain in 20 presume, intended her prophecy as a com­ remain essentially undeformed over life­ to 200 million years. ment on the Lord's omnipotence; it could spans of 100 to 200 million years, The continent of North America must equally be interpreted as a comment on whereas North America is straining at a be much weaker than the stiff oceanic His longevity. D rate of 10- 15 to 10- 16 s- 1 in response to plates, so weak in fact that it makes no forces of the same magnitude. These sense to treat it as a plate at all. Moun­ Philip England is in the Department of rates of strain may seem slow, but they tains do indeed flow, though at a rate that Earth Sciences, University of Oxford, Parks are brisk in geological terms - they is slow on a human timescale. Deborah, I Road, Oxford OX1 3PR, UK. OBITUARY------~ Colin S. Pittendrigh (1918-96) COLIN S. Pittendrigh, founder of the eclosion (pupal emergence) rhythm of many in the field moved in that direc• modern field of circadian and Drosophila pseudoobscura and quickly tion, he began to study photoperiodic for many years its most articulate verified three central predictions: the time measurement, an interest that oc• spokesman, died in Bozeman, Mon• eclosion rhythm persists in the absence cupied the rest of his career. Building tana, on 18 March. of temporal cues from the environment on a prescient insight of Erwin Bunning Pitt, as he was universally known, (that is, under constant conditions in the and a beautiful experiment by K. K. took a first degree in at the Uni• laboratory); its period varies only slightly Nanda and K. C. Hamner, he developed versity of Durham, and in the Second with changes in ambient temperature (a a set of logically tight arguments and World War worked on malaria control in prerequisite for accurate time-keeping); designed a series of elegant experi• Trinidad, studying the anopheline mos• and it can be entrained by cycles of light ments that convincingly demonstrated quitoes that breed in bromeliad that the measures ponds. During that period he made daylength and thus times many of substantial contributions to under• the adaptive responses of organisms standing of bromeliad evolution and to seasonal change. his interest in rhythmicity was Pitt was always interested in the kindled by observing the biting power of language to direct thought, rhythms of malaria-carrying mos• and over the past few years he quitoes. After the war he completed became convinced that the term a PhD under the supervision of 'biological clock' had outlived its at Colum• usefulness. He perceived that the bia University, moving to Princeton central function of the circadian in 1947. There he taught a memo• system is to provide a temporal rable course in introductory biology, framework within the organism or and notably, as dean of the cell: to emphasize this view, he graduate school, was instrumental preferred the term 'temporal pro• in making admission to Princeton gramme' to 'clock'. open to women. In 1969 he moved Although his experimental work to Stanford, where he remained was almost entirely directed at un• until his retirement in 1984. derstanding circadian rhythmicity, His early and seminal insight was his thinking was dominated by evo• that the many rhythms expressed lutionary considerations. In one of by living things in the real world are his papers - which is still well the consequence of endogenous, worth reading - he originated the self-sustained biological oscillations concept of 'teleonomy' as a neces• that are entrained (synchronized) by sary and respectable alternative to environmental cycles. Although this 'teleology' with its unacceptable view seems obvious now, it was accep• or temperature within a narrow range baggage (Chapter 8 in Behavior and ted only slowly because it seemed around its natural period. Evolution, Yale University Press, 1958). unnecessarily complex. Why should Together with his long-time friend and By force of intellect and personality, natural selection favour an internal os• scientific colleague, Jurgen Aschoff, Pitt exerted a profound in• cillator when the environment is replete led the work of the next decade which fluence on the development of a field with temporal cues? One answer was established that biological clocks with which, very early on, he realized is cen• contained in the earlier research of G. nearly identical formal properties occur tral to our understanding of biological Kramer and K. von Frisch on Sun-com• in virtually all eukaryotic organisms. organization. It has taken many years pass orientation in birds and bees. To They provide temporal frameworks for for generally to catch up with use the Sun as a compass animals need processes as different as photosynthesis his vision, but it is now clear that he the equivalent of a clock, and it was in green plants, spore formation in was right and the hunt is on for under• this work that led Pitt to the inspired fungi, cell division in the ears of mice, lying circadian mechanisms at the cel• guess that this same clock times many and human cognitive performance. The lular and molecular levels. Those of us biological processes and is indeed a recent demonstration of a clock in a - and there are many - who were general property of cells and organisms. cyanobacterium extends the generaliza• privileged to know and work with Pitt Many clear predictions emerged from tion to the prokaryotes. will never forget him as a scientist or as this new view of rhythmicity. In the mid- Although Pitt participated in one of a man. 195Os, Pitt, along with his graduate the earliest identifications of a circadian students and close associate Victor pacemaker in a multicellular organism Michael Menaker is in the Department Bruce, began testing them. Pitt himself (in the optic lobe of the cockroach), of Biology, , Char• concentrated on the beautifully precise physiology was not his metier. While lottesville, Virginia 22903-2477, USA.

24 1\11\TURE · VOL 381 · 2 MAY 1996