Intro to Course, What is Life?, and the Scientific Method

Today's lecture will:

  1. Outline the goals and methods of the course.
  2. Examine the core of what makes the Earth unique and forms the subject of this course.
  3. Look at the scientific method, how it applies to the Life System, and the unique aspects of studying the life system.

Major concepts (in addition to the course description):

  1. The Nature of Life
  2. Proximal, Distal, and Final causes
  3. The Scientific Method
  4. Comparative Method
  5. Natural Experiments

I. Outline the goals and methods of the course

The basic course description is given at - and the syllabus at -

Grades will be determined by three in-class exams, three take home exams, one each at the end of each section, and your lab and field trip work.

Field trips are substituted for labs fairly often, most are self-guided but must be done by a specific date, a few are group field trips given on a specific day. The field trips are mandatory.

In specific, the grade breakdown is as follows.

Basis of Grade Description Percent of Grade
3 in-class exams One mutiple choice and short-answer exam at the end of each of the 3 parts of the course 33 %
Final Exam An essay or problem-type final exam at the end of the semester. 33 %
Labs Once a week labs, self guided field trips, or group field trips and associated homework 33 %

Textbook: The textbook for the course is: Raven, P. H., Johnson, G. B., Losos, J.B. & Singer 2005, Biology (7th ed.), McGraw-Hill, Boston, +1250 p.

II. What is Life?

What makes The Earth unique?... Life makes it unique.

What special properties does life have?

  1. Life is active chemical system separated from its surroundings and out of chemical equilibrium with its surroundings. Chemical equilibrium = death.
  2. Life reproduces with heredity
  3. There is variation in that heredity
  4. There is evolution of populations, adaptation, and innovation
  5. There are species that are reproductively isolated from other species and on their own evolutionary trajectories
  6. Species make societies of kin and parasitic to symbiotic relationships with other species.

These properties of life produce the world as we now know it. As we shall see, the composition of the atmosphere, and our climate, and perhaps even the structure of the Earth's surface itself is due to life processes within the Earth System.

What distinguishes the study of the Life System from the Climate or the Solid Earth Systems?

We must look at a rather venerable bit of philosophy, one which should be mulled over many times: The three causes of Aristotle, which are the Proximal, Ultimate (Distal), and Final.

Proximal cause is the immediate cause of something.

Why does our heart beat?

Our heart beats to move our blood - physiologist answers.

Ultimate cause is the result of processes no longer in evidence.

Our heart beats because our ancestors had hearts which beat and we inherited the heart and its actions - a paleontologist responds.

Final cause is the Why?, implies meaning, and is often considered existential, or teleological, but maybe not always.

Our heart beats because God made it so - the theologian speculates.

But, our heart also beats because of genetic instructions followed during our assembly while we developed from fertilized egg to baby - the evolutionary biologist says.

We can use this mode of thinking to examine the Earth System.

Perhaps the single most important difference in studying the Life aspects of the Earth System is that Life gives a profound direction to Earth history, as Life itself has a very strong direction.

Thus, ultimate causes are a much more obvious when studying the Life System.

For example, much can be understood about the Climate System by considering the numerous proximal causes we can see and measure. These comprise the physics of the Climate System, the understanding and specification of which allow the construction of mathematical models from something close to first principles.

In contrast, we have no "physics" of the Life System - no way to construct a mathematical model of Life from first principles. Instead, Life is perhaps best understood within the context of evolution - and evolution and the history of evolution is mostly a study of ultimate cause.

Even when considered within the "physiology of the life system", which we will do, the ultimate causes of how the system came to be will be a major part of our inquiry.

It is even possible that final cause may play a role in our explanations. The Gaia hypothesis of Lovelock implies a goal of the Life System in regulating climate. We will spend some time considering this highly controversial subject.

III. The Scientific Method

Environmental Science vs. Environmentalism

Although the two terms are nearly indistinguishable by contemporary society, a very important distinction exist - the first is a science discipline, or body of knowledge while the second is a concern.

Consider -

In 1798 Thomas Malthus expressed concerns regarding the ability of agricultural practices to keep pace with population growth.

In the early 20th century John Muir formed the Sierra Club in a grass roots effort to set aside and protect portions of Sierra Nevada, forming a refuge where humans were secondary to nature.

In 1963 Rachel Carson published a know historic book, Silent Spring, describing the dangers of pesticides and chemical pollution to our environment.

In 1992, Al Gore, former Vice President of the United States published a best selling book, EARTH IN THE BALANCE: Ecology and the Human Spirit

These are all examples of environmentalism, and each of the examples had dramatic and important consequences. Malthusian equations have often been used, invoked and even tested in the ensuing 200 years. John Muir's efforts resulted not only in the formation of the Sierra Club but also the formation of the National Park system (by President Theodore Roosevelt). The publication of Silent Spring changed the way society thinks about agriculture, industry and science, and the fact the Vice President of the United States is a published author of a "landmark" book on the global environmental crisis has pushed environmentalism to a new height of public awareness.

Despite the importance of these (and countless other) contributions, it is critical to distinguish these from environmental science.

"Environmentalist are people who believe that human actions are leading to the degradation of the planet and who object to this degradation on aesthetic, moral, and pragmatic grounds. Their arguments may be drawn on scientific data, but they are just as likely to be based on emotional appeal or on ethical or moral criteria." - MB Bush

Environmentalism and environmental science are important, having their place in modern society. The key is to realize the distinctions.

By contrast, Environmental Science is investigative and hypothesis driven, using a set of rules known as the scientific method. As with all basic sciences, the ultimate goal is to define the problem of interest based on the principles of the physical laws of nature, or at least to describe findings that are not inconsistent with these laws.

The scientific method is -

6 basic steps

  1. Observe some aspect of the universe
  2. Formulate a theory (hypothesis) that is consistent with the observation
  3. Use this theory to make a prediction
  4. Test the prediction through experimentation (or further observation)
  5. Modify the theory in light of the new results
  6. Go to step 3

A good hypothesis -

Scientific conduct requires the full and open communication of ideas, including successes and failures (most often via peer review publication). Environmental Scientist work under this system and add to our knowledge base accordingly. Many scientist are environmentalist, but it is not necessary to have environmental concerns to do good science. Similarly, many environmentalist base there arguments (concerns) on scientific findings, yet worrying about the degradation of the earth does not have to be (and is not always) based on scientific findings. In this course we study environmental science, stressing the scientific method. Our discussions will inevitably (and should) include some environmental concerns but it is important that we focus on the scientific findings.

Additional Information on this topic is available through the works of two famous philosophers of Science.

Karl Popper - via the Karl Popper Web

Thomas Kuhn - via, or a rather interseting sidelight on his recent - obituary

Also, you might want to take a look at the following link:

Richard Feynman - Cargo Cult Science adapted from a CalTech commencement addresses given in 1974. The lingo/examples may be a bit dated but the message is a valuable today as it was in 1974.

There are two unusual and related aspects of the scientific method used more often when examining the life system than other areas of inquiry.

These are the comparative method and "Natural Experiments".

The comparative method

The comparative method examines natural systems by selecting a series of living or fossil systems based on them being as similar as possible in all but one (or a few) critical features, the role of which you wish to examine. The differences among the systems may then be related (hopefully) to the variable you chose to let vary. We use the comparative method in the absence of being able to conduct a manipulative experiment on the systems we are examining. However, use of the comparative method is indirect and ultimately should lead to some mechanistic hypothesis that can at least in part be tested by direct experimental manipulation.

Use of "Natural Experiments"

Natural Experiments are perturbations of a system that have occurred by natural causes. A good physical example was the eruption of Mt. Pinetubo in the Philippines. It had been hypothesized that sulfate aerosols in the upper atmosphere cause an increase in atmospheric albedo and hence tend to cool the Earth. However different mathematical models gave different answers of whether this would or would not occur and to what degree. The eruption of Mt. Pinetubo but a known quantity of sulfate aerosols into the atmosphere and a several year (small) decline in temperature and measured albedo occurred. A human induced manipulative experiment would not have been desirable! In a similar way we can use events in the history of the Earth, such as asteroid impacts, to see how the Life System responds to a severe perturbation.

Updated January 13, 2006
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