Early Models of Evolution

Very Brief Summary of Babylonian and Egyptian Views

Ancient View of the Earth The Babylonian and Egyptian “creation” stories both include the idea of a primordial sea from which the Earth and life arose. These stories often included the idea of humans being born from a goddess. The primeval Chaos was a “god” who created people and nature and the other gods.

In some Mediterranean and/or northern European civilizations, some of the widely-accepted theories of the universe had the Earth as a flat disk floating on the world ocean which surrounded it. Below was water (forever?) and above was sky, the abode of the gods. The land portion included all that was known at the time, basically an area around the Mediterranean Sea. “Down” (somewhere under the world ocean?) was the underworld. What people were able to observe in their daily lives was an universal frame of reference. Obviously, if the Earth was round, any people, water, etc. on the bottom would fall off.

Early Greek Philosophers

The Greek philosophers were perhaps the first to separate the question of origins from their gods and goddesses. The Greeks believed that the gods and goddesses, too, were created out of the primordial substance(s). Greek thought went one step farther. They thought of air or water as the first cause of all life (both their gods and humans). These were not an air-god or water-god, and the gods (who were also created) did not create nature nor humans. The gods and humans both came from Gaia, mother Earth, who was not one of the gods on Mt. Olympus, but some sort of a predecessor to everything.

Among the Greek philosopers were:

• Thales (650 - 580 BC) regarded water as the cause, beginning, and end of all things. His ideas were probably the beginning of the controversy among the Greek philosophers regarding the importance of water vs. air vs. fire as the “primordial substance.”
• Anaximander (611 - 546 BC) is credited with the first written work on natural science, a classical poem entitled On Nature. In this poem, he presented what may be the first written theory of evolution. He wrote that animals arose from slime which had been evaporated by the sun. He thought that the first animals lived in the sea and had prickly, scaly coverings. As these fish-like creatures evolved, they moved onto land, shed their scaly coverings, and became humans.
• Heraclitus (around the same time) felt that the universe is continually changing, thus it is senseless to ask for its origins in the manner of a myth. He taught that there is no beginning or end, only existence.
• Xenophanes (b. 570 BC) was one of the first people to observe fossils in rock layers. Interestingly, he recognized that the rock in which the fossils were found had at one time been submerged mud. He explained the existance of fossils by saying that that the world evolved from a mixture of earth and water, and that the Earth will gradually be re-dissolved. He believed that the Earth has gone through this cycle several times leading up to the visible fossils.

Later Greek Philosophers

• Empedocles (~490 - ~440 BC) tried to solve the water-earth-fire debate by saying that there were not one nor two, but four original elements: Earth, Air, Fire, and Water. He thought that everything else came about through their combination and/or separation by the two opposite principles of Love and Strife.
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  Earth, Air, Fire, and Water
• Among the many things for which Plato (427 - 343 BC) is remembered is his idea that there were two worlds. He said the world which we see is just an illusion, evil, an imperfect copy of the real world, transitory, and will decay. The real world which we cannot see because it’s invisible, is good, perfect, eternal, and static or unchanging. In the real world, there is obviously no variation or change, nor need for any, because all the organisms there are perfect. The variation we see among organisms here is because they are imperfect copies of the real “types” in the real world. This “pagan” idea was borrowed and incorporated into Christian beliefs, and in sharp contrast to the Jewish belief that we are caretakers of the Earth, has been used to justify our wanton trashing of the planet (“Who cares, since it’s evil and temporary, anyway”).
• Aristotle (384 - 322 BC), one of Plato’s most famous pupils, said that species are fixed in a hierarchy from simplest to most complex, like rungs on a ladder (the Scala naturae) with no vacancies, no mobility, and no change/evolution possible since all the spots were full. Later, these thoughts were incorporated into Christian views, along with the Hebrew idea that life is created. This view has dominated Western thought for about 2000 years.

Hebrews (Influenced by Mesopotamians and Egyptians)

The Hebrew people lived in between the Babylonians (Mesopotamians) and the Egyptains, and based much of their thoughts and knowledge on the influence of their neighbors to either side. In many respects, their creation story is similar to those of their neighbors, especially the Babylonians, but their God pre-existed before was separate from the primeval chaos, and he created both nature and people.

1700s through Early- and Mid-1800s

In more recent times, Georges Buffon (mid-1700s) was a Frenchman who studied fossils, and was among the first to suggest the Earth is older than 6000 years.

Water-Eroded Gorge of Green River, E. Utah

James Hutton (1726 - 1797) published a paper in 1795 (which was later refined/modified by Charles Lyell) in which he said that land forms can be accounted for by current mechanisms; for example, a gorge was cut by the river running through it, and was not always there. From this, he drew two conclusions:

1. slow, subtle, continuous change over a long time has a profound effect, and
2. if geological change comes from this slow process, then the Earth is very old, much older than Archbishop Ussher said.

Needless to say, this sparked much controversy because it was a challenge to the prevalent theory on the age of the Earth, where we came from (a challenge to the Christian Church’s interpretation of the book of Genesis), etc. This was a major challenge to the authority of the Christian Church and the beginnings of our modern-day split between religion and science (objective vs. subjective thought).

Fern Fossil in Coal Rev. Thomas Malthus (publ 1798), a British sociologist, looked at conditions in the poor neighborhoods of London. He said that in humans, the problems of disease, suffering, starvation etc. were a consequence of the potential for the human population to grow faster than technology could keep up with. Things like the supplies of food, medical care, etc. were limited in comparison to the size of the population, thus there was competition for available resources and only the strong and healthy would survive. He was, thus, the first to talk about survival of the fittest.

William “Strata” Smith (1769 - 1839), an English surveyor, was the first to scientifically study the distribution of fossils. He studied the order of rock strata or layers and noted that the same strata in different areas of England contained the same fossils. He found he could actually use the fossils in the various strata as indicators of which rock layer he was examining.

Lamarckian Evolution Jean Baptiste Lamarck (publ 1802 or 1809) developed a theory of evolution in which the main points were:

1. evolution or change within a species is driven by an innate, inner striving toward greater perfection,
2. use or disuse of various organs made them larger or smaller, accordingly, and
3. these acquired traits could be inherited or passed on to offspring (inheritance of acquired traits).

A number of subsequent attempts were made to prove or disprove this theory without the benefit of our modern knowledge of genetics. One experiment involved amputation of mouse tails for successive generations, showing that even after twenty generations, there was no effect: baby mice were still born with tails. The Jewish practice of circumcision was also cited as opposing evidence, since obviously it had caused no long-lasting change in the population and still needed to be done to each new boy baby. Lamarck’s theory seemed to make sense in the light of the then-accepted theory of pangenes coming from the body parts to make up the homunculus. The classic example he used was giraffes. He felt that giraffes’ necks got longer because they stretched to reach higher leaves, and this was passed on to their babies. Another example, to make the fallacy of his theory more apparent, would be two people who developed large arm muscles because they were blacksmiths, tennis players, or weight-lifters having a baby who was born with larger than normal arm muscles.

Late-1800s through Mid-1900s

Louis Pasteur (publ 1860) disproved spontaneous generation for smaller organisms (bacteria). Up until this time, people thought that bacteria and other microscopic organisms could just come into existance from changes in the external environment. Pasteur’s experiment with flasks with straight vs. curved (swan-neck) flasks showed that for bacteria to grow in a sterile medium, their ancestors must first “fall” into the medium from somewhere else (there are many bacteria afloat in the air around us).

Charles Darwin published the Origin of Species in 1859. His theories and where they have led will be discussed in a subsequent class period.

Alexander Ivanovich Oparin (publ 1936), a Russian scientist, in The Origins of Life, described hypothetical conditions which he felt would have been necessary for life to first come into existence on early Earth. He thought the atmosphere was made largely of methane, ammonia, etc. and that there was much more volcanic activity and lightening than now. This theory was later tested by an experiment done by Stanley Miller as a grad student under Harold Urey in 1953. This experiment will be covered in greater depth in a subsequent discussion.