This paper was originally published by the American Association of Engineering Societies (Washington D.C.), in a report "Production Efficiencies: The Engineers' Report," pp. 14-18, 1999.
It was republished in: IEEE Aerospace and Electronic SYSTEMS 14(10):3-6, October 1999.
The paper is based on a talk Jesse gave at the UN Commission on Sustainable Development meetings in New York in April 1999.


Keywords: decarbonization, agricultural land use.

(Note: The figures are at the end of this document for easier online reading.)

Because the Brain Does Not Change, Technology Must

Jesse H. Ausubel

The Program for the Human Environment
The Rockefeller University
1230 York Ave., New York, NY, 10021.

My message is my title: Because the Human Brain Does Not Change, Technology Must. That is, technology must change, must improve, to accommodate billions more people and to lift the standard of living. Engineers, receiving feedback from the market and regulated wisely in the public interest, do much of the improving. Thus, the chance for improving Earth’s environment hinges on engineers, and therefore their social context and technical vision. [1]

First I will explain what I mean by the unchanging human brain. Then I will exemplify technical change in energy and agriculture in the cardinal directions it must go.

The Triune Brain

In a remarkable 1990 book, The Triune Brain in Evolution , neuroscientist Paul MacLean explained that humans have three brains, each developed during a stage of evolution. [2] The earliest, found in reptiles, MacLean calls the snake brain. In mammals another brain appeared, the paleomammalian, with new particular behavior, for example, care of the young and mutual grooming. In humans came the most recent evolutionary structure, the hugely expanded neocortex. This neomammalian brain enabled language, visualization, and symbolic skills. But economical evolution did not replace the reptilian brain, it added. Thus, we share primal patterns of behavior with other animals, just as they share those brain structures. The snake brain controls courtship, patrolling of territory (including our daily 75-minute travel budget), displays of dominance and submission, and flocking. And makes most of the sensational news.

Our brains and thus our basic instincts and behaviors have remained unchanged for a million years or more. They will not change on time scales considered for “sustainable development.”

Of course, innovations may occur that control individual and social behavior. Law and religion both try, though the snake brain keeps reasserting itself, in crime and in punishment. Pharmacology also tries, with increasing success. Sales of new “anti-depressants,” mostly tinkering with serotonin in the brain, are about $10 billion in 1999, having penetrated only perhaps 10% of their global market.

Because, it seems to me, these forms of social control are unreliable, we should emphasis our greatest success, bettering technique. Since ever, homo faber has been trying to make things better and to make better things. During the past two centuries we have become more systematic and aggressive about it, through the diffusion of research & development and the institutions that perform them, including corporations and universities.

Let me now focus on two cardinal directions for technique, for engineering, decarbonization of energy and landless agriculture.


Carbon matters because it burns; combustion releases energy. But burnt carbon in local places can cause smog and in very large amounts can change the global climate. Raw carbon blackens miners' lungs and escapes from containers to form spills and slicks. Carbon enters the energy economy in the hydrocarbon fuels, coal, oil, and gas, as well as wood. In fact, the truly desirable element in these fuels for energy generation is not their carbon (C) but their hydrogen (H).

Wood is made of much cellulose and some lignin. Heated cellulose leaves charcoal, almost pure carbon. Lignin has a complex benzenic structure with an H:C ratio of about 0.5. Combining the pure carbon of cellulose and the 0.5 ratio of lignin, wood with 20% lignin effectively has an H:C ratio of 0.1. Said differently, wood weighs in heavily at ten effective Cs for each H. Coal approaches parity with one or two Cs per H, while oil improves to two H per C, and a molecule of natural gas (methane) is a carbon-trim CH 4.

The most important single finding from thirty years of energy studies is that that for two hundred years the world has progressively lightened its energy diet by favoring hydrogen atoms over carbon in our hydrocarbon stew (Figure 1). We will and must continue to do so. The increasing density of end-use of energy in cities finally accepts only natural gas, hydrogen, and electricity. Office buildings and homes reject smoking coals or hay.

The spectrum of national achievements also shows how far most of the world economy is from best practice in decarbonization. The present carbon intensity of the Chinese and Indian economies resembles those of America and Europe at the onset of industrialization in the nineteenth century.

Engineers must foster the unrelenting though slow ascendance of hydrogen in the energy market. We must squeeze most of the carbon out of the energy system and move, via natural gas, to a hydrogen economy. Hydrogen, fortunately, is the immaterial material. It can be manufactured from something abundant, namely water; it can substitute for most fuels; and its combustion to water vapor does not pollute.

Part of economizing on carbon is economizing on energy more broadly. Widgets work better than behavior modifications. The snake brain resists the carpool but grabs a lighter laptop. Fortunately, efficiency has been gaining in the generation of energy, in its transmission and distribution, and in the innumerable devices that finally consume energy (Figure 2). In fact, the struggle to make the most of our fires dates back at least 750,000 years to the ancient hearths of the Escale cave near Marseilles. A good stove did not emerge until 1744 CE. Benjamin Franklin's invention proved to be a momentous event for the forests and wood piles of America. The Franklin stove greatly reduced the amount of fuel required. Its widespread diffusion took a hundred years, however, because the American colonials were poor, development of manufactures sluggish, and iron scarce.

Looking globally in 1999, nothing in the energy game has changed, only now the stakes are higher. But we should be encouraged by our inventiveness with the performance of motors and lights. For the next couple of decades, the context indicates that priority and profit will come to those who build a highly efficient methane economy, the next stage of decarbonization.

Landless agriculture

As we must spare carbon while producing our energy, so must we spare land for nature while producing our food. Earth cannot sustain humans if it sustains humans alone. The direction, inevitably, is landless agriculture.

Yields per hectare measure the productivity of land and the efficiency of land use. During the past half-century, ratios of crops to land for the world's major grains-corn, rice, soybean, and wheat-have climbed fast on all six of the farm continents. Per hectare, world grain yields rose about two percent annually since 1960. The productivity gains have stabilized global cropland since mid-century, mitigating pressure for deforestation in all nations and allowing forests to spread again in many. A cluster of innovations including tractors, seeds, chemicals, and irrigation, joined through timely information flows and better organized markets, raised the yields to feed billions more without clearing new fields.

Fortunately, as Figure 3 shows, the agricultural production frontier remains spacious. On the same area, the average world farmer grows only about 20 percent of the corn of the top Iowa farmer, and the average Iowa farmer lags more than 30 years behind the state-of-the-art of his most productive neighbor. On average the world corn farmer has been making the greatest annual percentage improvement.

High-yield agriculture need not tarnish the land. The key is precision agriculture . This approach to farming relies on technology and information to help the grower use precise amounts of inputs-fertilizer, pesticides, seed, water—exactly where they are needed. Precision agriculture includes grid soil sampling, field mapping, variable rate application, and yield monitoring—tied to global positioning systems. It helps the grower lower costs and improve yields in an environmentally responsible manner. Ohio farmers recently reported using one-third less lime after putting fields on square-foot satellite grids detailing areas that would benefit from fertilizer.

We have had two revolutions in agriculture in this century. The first came from mechanical engineers. The second came from chemical engineers. The next agricultural revolution will come from information engineers, physical and genetic. What do the past and future agricultural revolutions mean for land?

For centuries land cropped expanded faster than population, and cropland per person rose (Figure 4). Fifty years ago farmers stopped plowing up nature. Meanwhile, growth in calories in the world’s food supply has continued to outpace population, especially in poor countries. To produce their present crop of wheat, Indian farmers would need to farm more than three times as much land today as they actually do, if their yields had remained at their 1966 level. By raising yields, Indian wheat farmers have spared nearly 50 million hectares, about the area of Madhya Pradesh or Spain. Let me offer a second comparison: a USA city of 500,000 people in 1994 and a USA city of 500,000 people with the 1994 diet and the yields of 1920. Farming as Americans did 75 years ago while eating as Americans do now would require 4 times as much land for the city, about 450,000 hectares instead of 110,000.

What can we look forward to globally? If during the next 60 to 70 years, the world farmer reaches the average yield of today’s USA corn grower, the ten billion people then likely to live on Earth will need only half of today’s cropland. This will happen if farmers maintain on average the yearly 2% worldwide yield growth of grains achieved since 1960, in other words, if dynamics, social learning, continues as usual. Even if the rate falls in half, an area the size of India, globally, will revert from agriculture to woodland or other uses.

Importantly, a vegetarian diet of 3,000 primary calories per day halves the difficulty or doubles the land spared. However, I trust more in the technical advance of farmers than in behavioral change by eaters.

So the challenge for the next decades in agriculture remains clear: lift yields while minimizing environmental fall out. Use less land.

And lift inhibitions on the imaginations of our food engineers. Let me offer a shocking idea to show how high we might raise limits. Going back to basics on food, we depend on the hydrogen produced by the chlorophyll of plants. With hydrogen, produced by nuclear power plants, for example, a plethora of micro-organisms can cook up the variety of substances in our diet. For decades, microbiologists have produced food by cultivating hydrogenomonas on a diet of H 2, CO 2, and a little O 2. They make nice proteins that taste like hazelnut. A person consumes around 100 watts. A current nuclear power plant has a power of a couple of gigawatts, enough to supply food for a few million people, on perhaps 1000 hectares for the Power Park. So, the nuclear plant can feed 2000 people per hectare. Iowa’s master corn growers feed about 80. So, WITH CURRENT TECHNOLOGY, we can do 25 times better than the best Iowa corn field. And finally decouple food and land.


If behavior and technology do not change, more numerous humans will trample the earth and endanger our own survival. The snake brain in each of us makes me cautious about relying heavily on changes in behavior. In contrast, centuries of extraordinary technical progress give me great confidence that diffusion of our best practices and continuing innovation can advance us much further in decarbonization, landless agriculture, and other cardinal directions for a prosperous, green environment. For engineers and others in the technical enterprise the urgency and prizes for sustaining their contributions could not be higher. Because the human brain does not change, technology must.

Acknowledgement: Thanks to Perrin Meyer for assistance.

Figure 1: World primary energy sources have declined in carbon intensity since 1860. The evolution is seen in the ratio of hydrogen (H) to carbon (C) in the world fuel mix, graphed on a logarithmic scale, analyzed as a logistic growth process and plotted in the linear transform of the logistic (S) curve. Progression of the ratio above natural gas (methane, CH 4) requires production of large amounts of hydrogen fuel with non-fossil energy.

Figure 2: Energy efficiency is a term of modern invention, but the efficiency of energy conversion devices has been increasing for hundreds and probably thousands of years. Improvements in motors and lamps are analyzed here in the linear transform of the logistic (S-shaped) growth process.

Figure 3: The trends of maize yields grown by the winners of the Iowa Master Corn Growers Contest and of average yields of Iowa, World, and Brazilian farmers, and the average annual rise since 1960.

Figure 4: The average cropland per person since about the year 1700. The star shows the small amount of land required by an Iowa Master corn grower to produce the calories needed to sustain a person for a year.


[1] Technical information and sources for the text and figures are found in papers on-line at See, for example, "The Liberation of the Environment," Jesse H. Ausubel; "Lightening the Tread of Population on the Land: American Examples," Paul E. Waggoner, Jesse H. Ausubel, and Iddo K. Wernick; and "Energy and Environment: The Light Path," Jesse H. Ausubel.

[2] Paul D. MacLean, The Triune Brain in Evolution: Role in Paleocerebral Functions, Plenum, New York, 1990.