Notes on the Web - Unit One - Part 4

 

Scientific Thought: A Brief History

Bruce G. Stewart

 

General Objectives and Study Guide

 

Your objectives for these Notes on the Web and associated readings and exercises are:

Related Textbook Readings:

Advances in Basic Knowledge and Social Structure

Basic Survival Knowledge. Humans, like all animals, must fulfill basic needs for survival in their environment. Modern humans share common ancestry with a number of extinct human species and genera, and we may presume that they had a functional knowledge of nature. Knowing dangerous from benign animals, nutritional versus poisonous plants, and other similar basic knowledge would have been critical. Examples of early species or subspecies related to modern humans include Australopithecus afarensis (dating to at least the late Pliocene over 4.2 million years before present), Homo habilis and H. erectus (dating back to 2.0-1.5 million years BP), and Homo neanderthalensis (dating back to 100,000 to 50,000 years ago). Neanderthals are so similar to our own species, Home sapiens, that they are sometimes classified as a subspecies (geographic form) of our species. Also note that there are other species known from the fossil record than these listed above.

Interpretation of physical evidence from fossil forms and modern humans shows that the brain characteristics changed in ways that promoted the accumulation, storage, and communication of knowledge. Most striking was the size increase in the cerebrum, that part of the brain related to reasoning and speech. Brain case volumes progressively increased: 400-550cm3 in Australopithicus sp.; 600+ cm3 in H. habilis; 850-1000 cm3 in H. erectus; and 1600 cm3 in H. sapiens neanderthalensis. Paleontologists have discovered other evidence of increased abilities and knowledge in these early species. For example, pebble tools were used by H. habilis, stone hand axes were used by H. erectus, and Homo neanderthalensis used a variety of very sophisticated stone tools.

Symbolizing. One way that knowledge can be transmitted is by direct learning by one individual from another. A possessor of knowledge may verbally communicate his or her knowledge to another (oral traditions) or others may learn by observing the experienced perform. Unfortunately, there are limits to the amount of knowledge that can be preserved in this manner. Take language as an example. In Oklahoma, several Native American languages are now spoken by fewer than ten elderly members of the original tribes! The languages are disappearing because there are no physical symbols representing the spoken word.

External abstract symbols represented the beginnings of storing knowledge outside the brain for preservation and transmission to others, even across generations. The earliest evidence of symbols produced by our own subspecies (Homo sapiens sapiens) dates back to at least 35,000 years ago. Famous cave sites in France preserve ancient symbols depicting important objects and events known to the early members of our species. Visit this link to learn about one such cave, Grotto Chauvet. Here is another link to an extensive website on the same cave if you would like to experience a "virtual" exploration: Chauvet-Pont-D'Arc. In the New World, many early cultures (e.g. the Olmec of southern Mexico) produced impressive sculptures and paintings representing individuals, deities and other items of cultural importance. We still marvel at these symbolic representations today. I will show you photographs of many of these in class. External symbolism was the necessary precursor to writing.

Writing. Writing consists of organized arrangements of standard symbols that store and convey information. Writing allows long-term accumulation, preservation, and transmission of large bodies of knowledge. Evidence of true writing in the Old World dates back to 6000 years ago when the Sumerians had developed cuneiform symbols that they imprinted on clay tablets. Much of the information stored was practical everyday information on business records. Archeological sites have been found that indicate teaching of the written language occurred. Writing would spread or develop independently in many groups over the millennia that followed. The impressive early writings of the Egyptians, for example, allow experts to read about the history and beliefs of that culture. The Maya of southern Mexico and Central America developed the earliest true writing system in the New World. In our class, I will share some of my photographs of Maya archeological sites.

City-State Governments. Centralized socio-political centers developed that included an educated elite who held power in part due to their functional knowledge of nature. These "city-states" defended a region in which resources were available to support the population. Agriculture and trade were important and "job types" diversified. This "division of labor" in such societies allowed for this educated elite to greatly advance their pursuit of knowledge. They no longer had to spend their time just surviving. Examples of Old World city-state cultures include the Babylonians, Egyptians, and Romans. The earliest of these dates back a few thousand years. Several hundred years ago in the New World, the Maya, Inca, Aztec, and other many other Native American groups developed city-state cultures. These cultures developed advanced, functional knowledge of stars, planets, time, and a host of other natural phenomena.

Ancient Science – The Greek Civilization

Perhaps it is impossible to identify a specific origin of scientific knowledge, if we broadly define science as simply acquiring functional knowledge of nature. Lloyd (1970) states that by this definition of science "...no human society is or ever has been without the rudiments of science." In modern terms, however, science involves specific types of activities, logical thought processes, and the application of mathematics (e.g. statistics). Along these lines, philosophy and science as we know them today originated with the early Greek civilization. A few hundred years before the birth of Christ, the great philosophers of Greece were proposing natural explanations for phenomena that had previously been explained only by reference to supernatural myth or tradition. Men like Thales, Aristotle, Democritus, Hippocrates, Aristarchus, Ptolemy, Galen and others made important contributions in many areas of study. We need not go into the details here; you may read about these elsewhere if you wish. However, I do wish to bring to light the originality and uniqueness of the approach used by Greek philosopher-scientists in their efforts to understand nature.

Early mythology included a vast array of beliefs on such subjects as origin of the Earth, origins of the Earth’s features, causes of Earth’s geologic activities, origins of life, origins of the stars, nature of the stars and other heavenly bodies, and so on. These were the same subjects addressed by the Greek philosopher-scientists! It was not what they explained, but how they explained them that made the Greeks so unique. Lloyd (1970) stated this succinctly as follows: "Their achievement was rather to have rejected supernatural explanations of natural phenomena and to have instituted the practice of rational criticism and debate in that context."

To be sure, the Greek philosopher-scientists proposed many amazingly accurate explanations of natural phenomena. They also proposed many mistaken explanations. This in no way, however, takes away from their great methodological leap in the way humans can learn about nature. Much of human understanding and belief about nature for the centuries that followed was based on the writings and teachings of the great Greek philosopher-scientists.

The Middle Ages: Centuries of Scientific Darkness

One might think that human scientific endeavors would have grown rapidly following the great discoveries and logical methods introduced by the Greek Civilization. What actually occurred should serve as a lesson for our modern scientific and technological world! After the decline of the Greek Civilization, there was a decline in the practice of scientific logic. Autocratic political systems did not allow free thought. Religious systems characterized by dogmatic beliefs (preconceived beliefs held to be true no matter what contradictory evidence might exist) wielded tremendous power over politics and society in general. Predictably, the rate of new scientific discoveries ground to a halt. This dark age of dogmatism would last for over 13 centuries! History shows us the importance of the freedom to use scientific methods if we are to continue to learn about nature!

Paradoxically, certain scientific contributions of the Greeks were highly respected. In fact, much of the knowledge gained by the "ancients" was accepted as consistent with divine revelation. For example, Galen, the great Greek anatomist of the second century AD made incredible contributions to the knowledge of animal and human anatomy and physiology. Galen’s work was dogmatically accepted by Christianity as the "revealed" anatomy. It was no longer acceptable to question the accuracy of Galen! The Greek-Egyptian, Ptolemy, affected human belief for centuries regarding the organization of the universe. He developed an elegant (though erroneous) Earth-centered model (theory) of the universe that was acceptable to the religious powers. In order to explain the odd retrograde motions of the planets, Ptolemy had to propose various unusual geometric patterns of motion. For example, he described epicycles (a small orbit of a planet around a point on its big circular orbit around the Earth) to explain retrograde motion exhibited by the path followed by planets as viewed from Earth. Of course, we know now that the planets do not orbit the Earth at all. But since Ptolemy’s model allowed decent predictions of planetary motion and because it was accepted as consistent with religious dogma, his model was not to be questioned for centuries to come!

The Re-emergence of Free Thinking and the Development of Modern Science

Flickers of free thinking can be identified in the history the 13th century. Roger Bacon (1210-1293) wrote, "Cease to be ruled by dogmas and authorities; look at the world!" Unfortunately, he was not representing society in general! Moore (1993) proposed that the year 1543 was perhaps the most significant birth date of the revival of science because of three major discoveries published in that year. The physical sciences led the way as you will see in the following paragraph.

Copernicus (1473-1543). Nicolas Copernicus was a Polish mathematician. He had access to and studied the works of Ptolemy. Copernicus developed a realistic sun-centered universe model and this would result in a true "paradigm shift’ in spite of objections of the Church. The major work of Copernicus "De Revolutionibus Orbium Coelestrium" was published in 1543, the year of his death. The book outraged the Church, even though a "disclaimer" was placed in the preface by another person after Copernicus’ death and before the book was published. To paraphrase the disclaimer, "Dear Pope, this book shouldn’t be taken as representing the way the solar system really is. It just gives a better mathematical way to predict the motion of the heavenly bodies." The disclaimer did not reduce the displeasure of the Church. Luther as quoted by Moore (1993) said about Copernicus: "This fool wishes to reverse the entire science for astronomy; but sacred Scripture tells us that Joshua commanded the sun to stand still, and not the earth."

Was uncensored free thought okay? Was it okay to disagree? Giordano Bruno, a Dominican monk, was burned at the stake in 1600 for his acceptance of the Copernican Model (Moore, 1993)! You be the judge!

Francis Bacon (1561-1626). Francis Bacon was a major figure who championed of scientific methods. His particular philosophy how to do science was so influential that historians refer to it as the "Baconian Philosophy of Science." Francis Bacon understood that science could not function when scientists were made to follow the "theological habit of starting the inquiry with a point of view that was accepted as true and then deducting the consequences" (Moore, 1993; p. 86)

Following the thinking of Francis Bacon, can you explain the meaning of the following quote? "Give me a fruitful error any time, full of seeds, bursting with its own corrections. You can keep your sterile truth for yourself."

Galileo (1564-1642). Galileo was no ordinary man. He was a man who followed is convictions. He believed in science as a way of knowing about the universe. Among his many scientific contributions, he provided convincing support of the Copernican model of the universe. Galileo added a new scientific tool to the study of astronomy in 1610, the telescope. For the first time in history, it was possible to see the celestial bodies as if they were closer. One of the things Galileo discovered was that the planet Venus is an orb and that it has phases similar to our Moon! At times, Venus appeared fully lit. At other times it would appear as a sliver and ultimately dark. Venus cycled between these extremes. Even more peculiar was the observation that the diameter of Venus changed along with the phases! Venus was small when it was in the full phase and gradually appeared larger as it approached the ‘new’ phase. Neither Ptolemy’s model of the solar system nor Aristotle’s model could account for either the changes in phases or the changes in diameter.

Amazing as it may seem, Galileo’s critics would not even accept his observational evidence. They said that an instrument like the telescope could not be trusted! Galileo was warned several times over the years not to write about his views. Finally the Church would take no more and severely punished Galileo. H. G. Wells described Galileo's 1663 clash with the Church as follows:

the church...decided that to believe that the earth was smaller and inferior to the sun made man and Christianity of no account...so Galileo, under threats of dire punishment, when he was an old man of sixty-nine, was made to recant this view and put the earth back in its place as the immovable centre of the universe. He knelt before ten cardinals in scarlet, an assembly august enough to overawe truth itself, while he amended the creation he had disarranged. The story has it that as he arose from his knees, after repeating his recantation, he muttered, "Eppur si muove"-"it moves nevertheless."

Ask yourself if you hold dogmatically to any views that go counter to well-established scientific theories. Does "popular vote" establish the "truth"? Certainly, the view of the Church in Galileo’s time did not change the fact that the Earth moves around the Sun and not vice versa! In spite of the dogmatic efforts of the Church, science was not to be denied. It simply worked too well!

Johannes Kepler (late 1500’s-early 1600’s). By analyzing astronomical data collected by his predecessor, Tycho Brahe, Kepler discovered that the planets move in elliptical rather than circular orbits. Thus, he is credited with developing the Laws of Elliptical Orbits. Prior to Kepler, circular motion was accepted as a natural and ubiquitous motion of heavenly bodies. However, Kepler found anomalies in the actual positions of planets (especially Mars) that were not predicted based on Copernicus' circular orbit model.

Isaac Newton - (1642-1727). Newton is considered one of the greatest scientists of all time. He discovered the fundamental relationships between gravity and motion. This provided the "how" to explain the mechanism of planetary motion. To do this, Newton had to invented new methods of mathematics to describe continuous motion and changes in force. Today, this mathematics is called calculus. The elegance of Newtonian physics led many to believe that all of the universe could be explained in precise mathematical terms.

Biology as a natural science. It is incredible that the physics of the solar system had been discovered by the early 1700’s. Newtonican physics is still used today in such practical applications as space travel. What was the state of biology as a natural science during this great period of physical science renaissance? Wouldn’t it seem logical that we would learn more about natural processes of life right here on Earth? Such was not the case. Discoveries in biology were indeed made; however, it would not be until the 19th century that biology truly entered its modern era. The following accounts guide us to that point.

Andreas Vesalius (1514-1564). Vesalius was a Belgian who was able to conduct human dissections and found that the great Greek anatomist, Galen (~129-200AD), was in error in many details of his descriptions of human anatomy. Vesalisus developed a "near-modern" understanding of basic human anatomy. His most significant work was "De Humani Corporis Fabrica" published in 1543. He also learned much about function of structures by conducting vivisection (i.e. dissections of living animals). For example, when he cut the vagus nerve of live pigs he found they could no longer squeal.

Was it okay to think freely about human anatomy? Consider the following quote from Moore (1993):

Initially Vesalius had much opposition, since even suggesting that such an ancient and respected authority as Galen might have erred was not in the best of taste. One brave, free spirit who suffered because he thought otherwise was Michael Servetus (1511-1553), a scholar of broad interests, mainly theological, but also a serious student of Galen. In the course of his studies, he came to the conclusion that Galen was not correct in all matters. Servetus hypothesized, for example, that blood does not pass directly through those Galenic pores from right ventricle to the left but instead goes from the right ventricle to the lungs, where it picks up air, and then back to the left ventricle. Mainly because he questioned Galen, whom the Church had named as the authority on anatomy and physiology, Servetus was captured while at prayer and, after a brief trial, was sent up in flames on October 27, 1553. Lest the reason be in doubt, one of his offending books was hung from his neck so it too was consumed on the pyre.

The Church was imprisoned by its own dogma. It had selected the best available scientific data before Copernicus and Vesalius and in that sense was up to date and as correct as it could be. However, concepts that become dogma are not easily changed by better data that suggest new concepts.

Ask yourself again if you hold dogmatically to any views that go counter to well-established scientific theories. Does "popular vote" establish the "truth"? How would you feel if you were punished for simply telling what you could see with your own eyes?

William Harvey (1578-1657). Harvey used careful observation and experimentation and was able to demonstrate that blood circulates constantly through the heart and vessels.

Antoni van Leeuwenhoek (1632-1657). Leeuwenhoek made glass bead lenses and used them to magnify previously unknown microscopic organisms. He discovered bacteria, protozoans, unicellular algae, rotifers and a host of other "animicules." This led the way to discarding supernatural explanations for many diseases later found to be caused by microbes.

Louis Pastuer. Pastuer demonstrated in 1862 that spontaneous generation of bacteria in current environments does not occur. This contributed to a more natural understanding of cellular reproduction. Hey! Note that this is over three centuries after Copernicus had properly organized the planets!

Charles Darwin (1809-1882). The work of Charles Darwin in the 19th century resulted in the development of modern biology! Charles Darwin was the first to discover a natural biological process, natural selection that could account for changes in species over time and ultimately in speciation (formation of new species). The first edition of The Origin of Species was published on 24 November 1859. The following comes from the Introduction of the sixth edition published in 1872:

When on board H.M.S. 'Beagle,' as naturalist, I was much struck with certain facts in the distribution of the organic beings inhabiting South America, and in the geological relations of the present to the past inhabitants of that continent. These facts, as will be seen in the latter chapters of this volume, seemed to throw some light on the origin of species--that mystery of mysteries, as it has been called by one of our greatest philosophers. On my return home, it occurred to me, in 1837, that something might perhaps be made out on this question by patiently accumulating and reflecting on all sorts of facts which could possibly have any bearing on it......

And reflect and study he did! In general outline, Darwin's theory of natural selection described in The Origin of Species has survived the scrutiny of thousands of subsequent studies over the past 135 years, and it has provided us with a natural not supernatural explanation for the origin of species. It has also allowed us to understand a myriad of observed patterns of structure, function and behavior in the living world. We will explore this topic in detail later in the semester.

Ask yourself for a third time if you hold dogmatically to any views that go counter to well-established scientific theories. Does "popular vote" establish the "truth"? Are you willing accept the fact that natural selection and change in species are natural processes that are known to occur in nature?

James Watson and Francis Crick. Watson and Crick published their discovery of the structure of the molecular structure of DNA (deoxyribonucleic acid) in 1953. They also published about the genetic implications of this incredible molecule in the same year. This has led to an explosion of research and deeper understanding about the function of living organisms and the mechanisms of heredity and evolution.

We will end our brief history here, but I trust that you will note the very recent date of the Watson and Crick discovery. The structure of DNA was not known when I was born! Realize how much we have progressed in the past one and one-half centuries in understanding natural processes in living things. Your textbook has a more comprehensive summary of the history of biology. We will learn some of the accomplishments and the individuals who made the discoveries other parts of our course as we discuss those topics.

Some Cited or Related Literature:

Lloyd, G. E. R. 1970. Early Greek Science: Thales to Aristotle. W. W. Norton & Company. New York. 156pp.

Lloyd, G. E. R. 1973. Greek Science After Aristotle. W. W. Norton & Company. New York. 189pp.

Moore, John A. 1993. Science as a way of knowing: the foundations of modern biology. Harvard University Press, Cambridge, Massachusetts. 530 pp.

Mayr, Ernst. 1985. The growth of biological thought. Harvard University Press, Cambridge, Massachusetts.

© 1999, 2005 Bruce G. Stewart

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