The 2,024th Meeting of the Society

February 18, 1994

The Crisis of Life on Earth and the Nature of Human Nature

Michael Robinson

National Zoological Park, Smithsonian Institution

About the Lecture

At the end of the Twentieth Century, humankind, a once ecologically insignificant organism, is changing the natural world at an unprecedented rate. The causes and effects of this change, particularly in the tropical rainforests, although highly publicized are not often understood. In this talk I will give emphasis to the unique complexity of tropical biology, illustrating this by using case-history studies from Smithsonian research; and examine some of the proximal causes of the destruction of the global centers of biodiversity. I will argue that much of the problem may be due to more fundamental causes and examine the evidence for there being deep-rooted biological imperatives that constrain our behavioral options even at the beginning of a new century. In short I would end by returning to the age-old question of the nature of human nature…if there is such a thing!

About the Speaker

Mr. Robinson, Director of the Smithsonian Institution's National Zoological Park, is an animal behaviorist and a tropical biologist. Immediately prior to his appointment to the National Zoo in May 1984, Mr. Robinson served as the Deputy Director of the Smithsonian Tropical Research Institute in Panama, which he joined in 1966 as a tropical biologist. He received his Doctor of Philosophy from Oxford University after being awarded his Bachelor of Science, Summa Cum laude, from the University of Wales. His scientific interests include predator-prey interactions, evolution of adaptations, tropical biology, courtship and mating behavior, phenology of arthropods, and freshwater biology. He is the author of more than 100 scientific papers and articles including a book on the courtship and mating behavior of spiders.


The President, Ms. Enig, called the 2024th meeting to order at 8:15 p.m. on February 18, 1994. The Recording Secretary read the minutes of the 2023th meeting and they were approved. The President then read a portion of the minutes from the 416th meeting, February 17, 1894.

The President introduced Mr. Michael H. Robinson of the National Zoological Park, Smithsonian Institution to discuss “The Crisis of Life on Earth and the Nature of Human Nature”

Mr. Robinson began by presenting a short visual test of rotation perception. Although untrained humans are usually not very successful, pigeons almost never fail because “the way they make a living” requires them while they are flying to recognize landmarks quickly and from any angle. Evolution has constrained each organism in the limits of its senses and its ability to integrate their perception. It is the challenge to man recognize such limitations in himself. The fallacies which may undermine man's reliance on deductive logic was illustrated by a personal anecdote. The egg-laying behavior of a certain spider from Papua New Guinea had never been observed in the wild. In captivity it laid its egg cases on the sides of the cage wall, and he duely reported that it must lay its eggs on the sides of rocks or trees. Only later when field evidence indicated that deduction may have been wrong, was soil provided in the cage and the spider was observed to lay the egg case in the soil.

The most serious danger may be that we shall not be able to change our behavior in time to save the planet. Medical science has increased longevity, but there has not been a balancing of the birth rate to maintain a constant population. In this century the population has grown by a factor of 3, the rate of consumption of fossil fuels has grown by a factor of 12, and the world economy has grown by a factor of 29. The environmental cost has been tremendous. For the contiguous United States less than 0.60f the land area covered by forest in 1620 remains. Now, in order to sustain that growth we can only succeed by increasing the “carrying capacity” of the arable land. We have, as Jacques Cousteau called it, “a tyranny of the present over the future".

Before 1982 it had been estimated that there were 1.5 million different species of insects in the world, and most of those were beetles. In that year Terry Erwin developed new techniques for more comprehensive sampling of species diversity in the canopies of tropical rain forests [1]. Based on the number of new species per tree he was able to find in the Amazon basin, he estimated that the number of different species must be between 15 and 30 million. This also illustrates the amazing complexity of life in the tropics. That variety, mostly still undocumented by science, is now threatened with extinction as the tropical rain forests are being destroyed just as the forests of the Europe and the United States were.

Mr. Robinson elaborated on the complexity of life in the tropics with many examples. There are 350 known species of bats in Panama; one of those eats only frogs and the frogs have had to adapt their mating calls to avoid preditation by the bat. There are several species of moths which live on sloths; one of those moths lives by drinking the sloths' tears. The investigation of one moth led to a vine on which it was an intermittent feeder. The vine was found to produce a sugar analog that is now being tested as a viricide, and as a treatment for diabetes and weight control.

The process of evolution may have constrained the developement of man by limiting the range of our senses, by limiting our ability to integrate the perception of those sense, and by limiting our repitoire of behavioral responses. Behaviors that were advantageous in our hunter-gatherer phase may be maladaptive now. Even our ability to learn, based as it is on observation and imitation, may be maladaptive. We must be aware of our vulnerabilities.

[1] T. Erwin, “Tropical Forest Canopies: The Last Biotic Frontier” Bulletin of the Entomological Society of America, Spring, 14-19, 1983.

Mr. Robinson then kindly answered questions from the audience.

The President thanked the speaker on behalf of the Society. There were no new members to be introduced. The President then announced the speaker for the next meeting, made announcements concerning parking and transportation, and adjourned the 2024th meeting at 9:48 p.m.

Attendance: 64
Temperature: +7.6°C
Weather: clear

Respectfully submitted,

John S. Garavelli
Recording Secretary