Skip to Content

On the Escape of Tigers

An Ecologic Note

A major class of ecologic phenomena involves the transfer of energy in such ways and amounts; and at such rapid rates, that inanimate or animate structures are damaged. The harmful interactions with people and property of hurricanes, earthquakes, projectiles, moving vehicles, ionizing radiation, lightning, conflagrations, and the cuts and bruises of daily life illustrates this class.

Ten Strategies for Reducing These Losses

Several strategies, in one mix or another, are available for reducing the human and economic losses that make this class of phenomena of social concern. In their logical sequence, they are as follows:

The first strategy is to prevent the marshalling of the form of energy in the first place: preventing the generation of thermal, kinetic, or electrical energy, or ionizing radiation; the manufacture of gunpowder; the concentration of U-235; the build-up of hurricanes, tornadoes, or tectonic stresses; the accumulation of snow where avalanches are possible; the elevating of skiers; the raising of babies above the floor, as to cribs and chairs from which they may fall; the starting and movement of vehicles; and so on, in the richness and variety of ecologic circumstances.

The second strategy is to reduce the amount of energy marshaled: reducing the amounts and concentrations of high school chemistry reagents, the size of bombs or firecrackers, the height of divers above swimming pools, or the speed of vehicles.

The third strategy is to prevent the release of the energy: preventing the discharge of nuclear devices, armed crossbows, gunpowder, or electricity; the descent of skiers, the fall of elevators; the jumping of would-be suicides; the undermining of cliffs; or the escape of tigers. An Old Testament writer illustrated this strategy in the context both of the architecture of his area and of the moral imperatives of this entire field: “When you build a new house, you shall make a parapet for your rook, that you may not bring the guilt of blood upon your house, if any one fall from it.” (Deuteronomy 22:8). This biblical position, incidentally, is fundamentally at variance with those of those who, by conditioned reflex, regard harmful interactions between man and his environment as problems requiring reforming imperfect man rather suitably modifying his environment.

The fourth strategy is to modify the rate or spatial distribution of release of the energy from it source: slowing the burning rate of explosives, reducing the slope of ski trails for beginners, and choosing the reentry speed and trajectory of space capsules. The third strategy is the limiting case of such release reduction, but is identified separately because in the real world is commonly involves substantially different circumstances and tactics.

The fifth strategy is to separate, in space or time, the energy being release from the susceptible structure, whether living or inanimate: the evacuation of the Bikini islanders and test personnel, the use of sidewalks and the phasing of pedestrian and vehicular traffic, the elimination of vehicles and their pathways from community areas commonly used by children and adults, the use of lightning rods, and the placing of electric power lines out of reach. This strategy, in a sense also concerned with rate-of-release modification, has as its hallmark the elimination of intersections of energy and susceptible structure–a common and important approach.

The very important sixth strategy uses not separation in time and space but separation by interposition of a material “barrier”: the use of electrical and thermal insulation, shoes, safety glasses, shin guards, helmets, shields, armor plate, torpedo nets, antiballistic missiles, lead aprons, buzz-aw guards, and boxing gloves. Not that some “barriers,” and ionizing radiation shields, attenuate or lessen but do not totally block this energy from reaching the structures to be protected. This strategy, although also a variety of rate-of-release modification, is separately identified because the tactics involved comprise of large, and usually clearly discrete, category.

The seventh strategy, into which the sixth blends, is also very important–to modify appropriately the contact surface, subsurface, or basic surface, as in eliminating, rounding, and softening corners, edges, and points with which people can, and therefore sooner or later do, come in contact. This strategy is widely overlooked in architecture with many minor and serious injuries the result. It is, however, increasingly reflected in automobile design and in such everyday measures as making lollipop sticks of cardboard and making some toys less harmful for children in impact. Despite the still only spotty application of such principles, the two basic requisites, large radius or curvature and softness, have been known since at least about 400 B.C., when the author of the treatise on head injury attributed to Hippocrates wrote: ‘of those who are wounded in the parts falls from a very high place upon a very hard and blunt object is in most danger of sustaining a fracture and contusion of the bone, and of having it depressed from its natural position; whereas he that falls upon more level ground, and upon a softer object, is likely to suffer less injury in the bone, or it may not be injured at all…” (On Injuries of the Head,” The Genuine works of Hippocrates, trans. F. Adams [The Williams and Wilkins Co., Baltimore, 1939]).

The eighth strategy in reducing losses in people and property is to strengthen the structure, living or non-living, that might otherwise be damaged by the energy transfer. Common tactics, often expensively under-applied, include tougher codes for earthquake, fire, and hurricane resistance. The training of athletes and soldiers has a similar purpose, among others, as does the treatment of hemophiliacs to reduce the results of subsequent mechanical insults. A successful therapeutic approach to reduce the osteoporosis of many post-menopausal women would also illustrate this strategy, as would a drug to increase resistance to ionizing radiation in civilian or military experience. (Vaccines, such as those for polio, yellow fever, and smallpox, are analogous strategies in the closely parallel set to reduce losses from infectious agents.)

The ninth strategy in loss reduction applies to the damage not prevented by measures under the right preceding–to move rapidly in detection and evaluation of damage that ha occurred or is occurring, and to counter its continuation and extension. The generation of a signal that response is required; the signal’s transfers, receipt, and evaluation; the decision and follow-through, are all elements here–whether the issue be an urban fire or wounds on the battlefield or highway. Sprinkler and other suppressor responses, firedoors, MAYDAY and SOS calls, fire alarms, emergency medical care, emergency transports, and related tactics all illustrate this countermeasure strategy. (Such tactics have close parallels in many earlier stages of the sequence discussed here, as for example, storm and tsunami warnings.)

The tenth strategy encompasses all the measures between the emergency period following the damaging energy exchange and the final stabilization of the process after appropriate intermediate and long-term reparative and rehabilitative measures. These may involve return to the pre-event status or stabilization in structurally or functionally altered states.

Separation of Loss Reduction and Causation

There are, of course, many, real-world variations on the main theme. These include those unique to each particular form of energy and those determined by the geometry and other characteristics of the energy’s path and the point of area and characteristics of the structure on which it impinges–whether a BB hits the forehead or the center of the cornea.

One point, however, is of overriding importance: subject to qualifications as noted subsequently, there is no logical reason why the rank order (or priority) of loss-reduction countermeasures generally considered must parallel the sequence, or rank order, of causes contributing to the result of damaged people or property. One can eliminate losses in broken teacups by packaging them properly (the sixth strategy), even though they be placed in motion in the hands of the postal service, vibrated, dropped, piled on, or otherwise abused. Similarly, a vehicle crash, per se, need necessities no injury, nor a hurricane housing damage.

Failure to understand this point in the context of measures to reduce highway losses underlies the common statement: ‘If it’s the driver, why talk the vehicle.” This confuses the rank or sequence of causes, on the one hand, with that of loss-reduction countermeasures–in this case “crash packaging”–on the other.

There are, nonetheless, practical limits in physics, biology, and strategy potentials. One final limit is operative at the boundary between the objectives of the eighth and ninth strategies. Once appreciable injury to man or to other living structure occurs, complete elimination of undesirable end results is often impossible, though appreciable reduction is commonly achievable. (This is often also true for inanimate structures, for example, teacups.) When lethal damage has occurred, the subsequent strategies, except as far as the strictly secondary salvage of parts is concerned, have no application.

There is another fundamental constraint. Generally speaking, the larger the amounts of energy involved in relation to the resistance to damage of the structures at risk, the earlier in the countermeasure sequence must the strategy of lie. In the ultimate case, that of a potential energy release of proportions that could not be countered to any satisfactory extent by any known means, the prevention of marshalling or of release, or both, becomes the only approach available. Furthermore, in such an ultimate case, if there is a finite probability of release, prevention of marshalling (and dismantling of stockpiles of energy already marshalled) becomes the only, and essential, strategy to assure that the undesirable end result cannot occur.

For Each Strategy and Analogous Opposite

Although the concern here is the reduction of damage produced by energy transfer, it is noteworthy that to each strategy there is an opposite focused on increasing damage. The latter are most commonly seen in collective and individual violence–as in war, homicide, and arson. Various of them are also seen in manufacturing, mining, machining, hunting, and some medical and other activities in which structural damage often of a very specific nature is sought. (A medical illustration would be the destruction of the anterior pituitary with a beam of ionizing radiation as a measure to eliminate pathologic hyperactivity.) For example, a maker or motor vehicles or of aircraft landing-gear struts–a product predictably subject to energy insults–could make his product more delicate, both to increase labor and sales of parts and materials, and to shorten its average useful life by decreasing the age at which commonplace amounts of damager increasingly exceed in cost the depreciating value of the product in use. The manufacturer might also design for difficulty or repair by using complex exterior sheet metal surfaces, making components difficult to get at, other means.

The type of categorization outlined here is similar to those useful for dealing systematically with other environmental problems and their ecology. In belief illustration, various species of toxic and environment-damaging atoms (such as lead), molecules (e.g. DDT), and mixtures (garbage and some air pollutants, among others) are marshaled, go through series of physical states and situations, interact with structures and systems of various characteristics, and produce damage in sequences leading to the final, stable results.

Similar comments can be made concerning the ecology of some of the viral, unicellular, and metazoan organisms that attack animate and inanimate structures; their hosts; and the types and stages of damage they produce.*

Sufficient differences among systems often exist, however–for example, the ecology of the agents of many arthropod-borne diseases is quite complex, and the life cycles of organisms such as schistosomes require two or more different host species in sequence–to preclude at this time many generalizations useful across the breadth of all environmental hazards and their damaging interactions with other organisms and structures.

A Systematic Analysis of Options

It has not generally been customary for individuals and organizations that influence, or are influence by, damage due to harmful transfers of energy to analyze systemically their options for loss reduction, the mix of strategies and tactics that might employ, and their cost. Yet, it is entirely feasible and not especially difficult to do so, although specific supporting data are still often lacking. In fact, unless such systematic analysis is done routinely and well, it is generally impossible to maximize the pay-offs both of loss-reduction planning and of resource allocations.

Such analysis is also needed to consider properly the problems inherent in the use of given strategies in specific situations. Different strategies to accomplish the same end commonly have different requirements; in kinds and numbers of people, in material resources, in capital investments, and in public and professional education, among others. In the case of some damage-reduction problems, particular strategies may require political and legislative action more than others. And, where the boundaries, correspondingly international action is commonly essential.

The types of concepts outlines in this note are basic to dealing with important aspects of the quality of life, and all of the professionals concerned with environment and with the public health need to understand and apply the principles involved–and not in the haphazard, spotty, and poorly conceptualized fashion now virtually universal. It is the purpose of this brief note to introduce the pathway along which this can be achieved.

William Haddon, Jr. is the former president of the Insurance Institute for Highway Safety.

Suggested Readings

W. Haddon, Jr., “Why the Issue Is Loss Reduction Rather Than Only Crash Prevention,” presented at the Automotive Engineering Congress, S.A.E., Detroit, Michigan, January 12, 1970, S.A.E. Preprint 700196.

W. Haddon, Jr., “The Changing Approach to eh Epidemiology, Prevention, and Amelioration of Trauma: the Transition to Approaches Etiologically Rather Than Descriptively Based,” American Journal of Publish Health, 58 1431-1438, 1968.

W. Haddon, Jr., “The Prevention of Accidents,” in Textbook of Preventative Medicine, ed. D.W. Clark and B. MacMahon Boston: Little, Brown and Company), pp. 591-621.

W. Haddon, Jr., E.A. Suchman, and D. Klein, Accident Research, Methods and Approaches, Harper and Row, 1964. (See especially Chapter 9 and 10).

*Actual and potential birth control and related strategies and tactics can be somewhat similarly categorized. Thus, in brief, beginning on the male line: preventing the marshalling of viable sperm (by castration or certain pharmacological agents); reducing the amount of sperm produced; preventing the release of semen (or of one of its necessary components, e.g. by vasectomy); modifying the rate or spatial distribution of release of semen (as in hypospadias, a usually developmental or traumatic condition in which the urethra opens on the underside of the penis, sometimes near its base); separating semen release in space or time from the susceptible ovum (e.g. continence, limiting intercourse to presumably nonfertile periods, coitus interrupts, and preventing a fertile ovum from being present when sperm arrive); separation by interposition of a material barrier (e.g. condoms, spermicidal creams, foams, jellies); increasing resistance of the ovum to penetration; making the ovum infertile, even if penetrate; prevention of implantation of the fertilized egg; abortion; and infanticide.

Keep Reading

Most Popular

How to opt out of Meta’s AI training

Your posts are a gold mine, especially as companies start to run out of AI training data.

The return of pneumatic tubes

Pneumatic tubes were supposed to revolutionize the world but have fallen by the wayside. Except in hospitals.

Why does AI hallucinate?

The tendency to make things up is holding chatbots back. But that’s just what they do.

How a simple circuit could offer an alternative to energy-intensive GPUs

The creative new approach could lead to more energy-efficient machine-learning hardware.

Stay connected

Illustration by Rose Wong

Get the latest updates from
MIT Technology Review

Discover special offers, top stories, upcoming events, and more.

Thank you for submitting your email!

Explore more newsletters

It looks like something went wrong.

We’re having trouble saving your preferences. Try refreshing this page and updating them one more time. If you continue to get this message, reach out to us at with a list of newsletters you’d like to receive.