…in the beginning there was chaos from which evolved order

[The Leaven – exploring the relationship between science and religion (cont)]

The application of molecular archaeology has largely denounced the explanation of creation as proposed by Babylonian type theories recorded in the Old Testament. Several views held at this time have been dispelled by Science. For instance, rain was thought to fall from seas separated from the Earth by a dome structure which the Creator called sky [Gen. 1, 6-7].

Then God commanded, “let there be a dome to divide the water and keep it in two separate places”- and it was done. So God made a dome, and it separated the water under it from the water above it. He named the dome “sky”.

Birds and fish were created on the fourth day, while animal life on Earth was created on the fifth. On the sixth day the Creator placed humans on Earth to control the animals that existed in the land and sea. The order in which the animals appear seems to be fairly logical, fish and birds being further down the food chain than the higher animals with humans at the very top. There is no mention of bacteria and parasites. Evolutionary speaking they should appear before the birds and fish in day three.

So God made a dome, and it separated the water under it from the water above it. He named the dome “sky”. Woodcut by Julius Schnorr von Carolsfeld 1860

Theories involving the spontaneous generation of living beings were widely accepted for centuries. The Greek philosophers Plato and Aristotle in the 4th Century BC held views that contradicted a gradual evolution of life forms. Plato argued that there were two worlds: one was real the other was imaginary. The variations that were present in plants and animals were merely imperfect illusions of an already perfect form. This philosophy was known as idealism or essentialism and ruled out evolution as organisms were already in the form that they were destined to become. Aristotle recognised that organisms could be arranged according to complexity this is often referred to as a scale of nature or scala naturae. He believed that there was an organism at each scale; species were fixed and no evolution occurred. This view persisted for 2000 years and was widely adopted by natural theologists who thought that the Creator had designed each species for a specific purpose.

Linnaeus in the 18th century adopted a filing system for all these species. He was a natural theologian who claimed that he had developed the classification system in order to reveal Gods plan, he clarifies this using the phrase:

Deus creavit, Linnaeus disposuit; God creates, Linnaeus arranges.

During the nineteenth century yeasts were thought to be part of the plant kingdom in the division of Thallophyta because they lacked true roots, stems and leaves. They were eventually classified as fungi because they do not contain chlorophyll or rely on photosynthesis to create energy. Instead they live a parasitic or saprophytic existence, living off the carbon sources supplied by other organisms. Like other species of fungi, yeast can also form spores. In the case of S. cerevisiae these are found in a sac called an ascus this has earned them the further classification of Ascomycetes.

Jean Baptiste Lamarck was one of the first biologists who proposed a theory of evolution in 1809. As curator of the invertebrate collection in the Natural History Museum in Paris, he observed that insects changed gradually over the centuries. He thought that microscopic creatures were at the bottom of evolution and generated spontaneously from inanimate material. Lamarck felt that creatures evolved towards greater complexity and that higher organisms were aiming towards perfection to become completely adapted to their environment. He proposed that organisms adapted continually thereby some aspects of their physiology grew stronger while others disappeared and that these life-time improvements could be passed on to their offspring. Lamarck’s hypotheses have been largely disproved but his views were revolutionary; he implied that species evolved and that they were not fixed. Darwin’s theory of natural selection was to directly challenge the current viewpoint of fixed design. Natural, or should it be supernatural, theology, was the accepted way of thinking and doing science, each species being allocated a specific niche by a supernatural being.

At an early age Darwin was already a keen naturalist and obtained a degree in theology at Christ College Cambridge where he became the protégé of the botanist Professor Henslow. When he was 22 he joined the crew of The Beagle, a survey ship whose mission was to chart the South American coastline. During this voyage he collected flora and fauna while others surveyed the coast. He was particularly interested in the diversity of species that were present in the Galapagos Islands and recovered over a dozen different types of Finch. Darwin began to understand through his own work, and that of others, that the origin of new species arose from a distant ancestor by the gradual accumulation of adaptations. He saw this within the beaks of the finches that he had collected from the Galapagos Islands. Each Finch had a specialised beak that was adapted to forage for the type of food found on its island of origin. This was visible evidence that selection through environmental factors could contribute to speciation.

Darwin’s drawings of beak variation in Finch species.

Darwin was reluctant to introduce his theories publicly because, being a theologian, he was aware of the controversy that this would cause. He wrote an essay on the origin of species in 1844 that remained unpublished until 1858 when extracts from it were presented to the Linnaean Society. In the same year another naturalist, Alfred Wallace published a paper on the evolution of new species. This prompted Darwin to complete his book the Origin of Species, which was published the following year. The Origin of Species presented a strong argument for natural selection through scientific evidence and became adopted by evolutionists as the primary text on the subject. At the time molecular genetics and the true nature of genetic inheritance were still undiscovered so Darwin adopted a Lamarckian approach to explain acquired characteristics. Where strengths acquired during the course of a life-time could be passed down to the next generation.

…my distant relative is a lower life form

[The Leaven – exploring the relationship between science and religion (cont)]

Through research by evolutionary biologists we have now discovered that humans are more closely related to leaven than early civilisations could have imagined. Many of the human proteins involved in the fundamental functions of the cell,such as DNA replication, are conserved in other organisms, even in yeast and bacteria. In fact some human DNA can be expressed in bacteria and yeast to produce protein. Proteins that are homologous in different species are known as orthologues. DNA processing proteins, such as Polymerases, are often found in this category. For this reason the mechanisms of mutation in mammalian cells can be studied equally as well in yeast cells.

The big question is then why did not all yeast cells evolve into complex multicellular organisms like humans or even plants? Why are there still primitive cells like bacteria? As George Carlin, so eloquently put it:

If man evolved from monkeys and apes, why do we still have monkeys and apes?

The answer is that organisms are continually evolving, they are constantly finding new ways to preserve or obtain energy, therefore new species could arise at any time and, as a consequence, there must always be lower and higher life forms. It is the diversity of Life that encourages adaptations. Through a constant competition to obtain energy, diversity provides the resources on which selection can act. For instance, a group of higher species A are infected by lower species B and some are killed. Some A species were able to survive because they have a mutation that makes them more resistant to species B  but it also makes them less resistant to species C. It flourishes until it encounters species C. As consequence of  this cycle of adaptations, species A no longer resembles its original form and becomes subspecies Ab. So evolution depends heavily on a changing environment and the ability of an organism to adapt.  This allows the evolutionary route to continue in a perpetual cycle of various adaptations until many species of organisms evolve. Darwin called this process natural selection or the preservation of favoured races in the struggle for life:

If under changing conditions of life organic beings present individual differences in almost every part of their structure, and this cannot be disputed; if there be, owing to their geometrical rate of increase, a severe struggle for life at some age, season, or year, and this certainly cannot be disputed; then, considering the infinite complexity of the relations of all organic beings to each other and to their conditions of life, causing an infinite diversity in structure, constitution, and habits, to be advantageous to them, it would be a most extraordinary fact if no variations had ever occurred useful to each being’s own welfare, in the same manner as so many variations have occurred useful to man. But if variations useful to any organic being ever do occur, assuredly individuals thus characterised will have the best chance of being preserved in the struggle for life; and from the strong principle of inheritance, these will tend to produce offspring similarly characterised. This principle of preservation, or the survival of the fittest, I have called Natural Selection. It leads to the improvement of each creature in relation to its organic or inorganic conditions of life; and consequently, in most cases, to what must be regarded as an advance in organisation. Nevertheless, low and simple forms will endure if well fitted for their simple conditions of life.

[Darwin, 1859]

Evolutionary selection relies on the chance that an adaptation will occur and that it will improve the fitness of a particular organism. This directly conflicts with early Christian beliefs that organisms do not evolve and remain as they were originally conceived.

Gradual evolution of 21st cent humans. A schematic representation by José-manuel Benitos.

The discovery of humans at various stages of evolution has diminished the concept that humans were created in their current form or generated spontaneously. Humans are thought to have evolved from primates that first appeared around 5-8 mya and share many similar characteristics to chimpanzees. In fact 98% of chimpanzee DNA is homologous to human but one of the greatest anatomical differences is in brain size. The chimpanzee’s brain weighs less than half a kilo while a human brain weighs around three times that much. Archaeological evidence suggests that three or four hominid species lived in the African continent several million years ago. Currently one of the earliest of these is known as a species called Ardipithecus ramidus.  Modern humans, Homo sapiens are thought to descend from Australopithecus anamensis, Australopithecus afarensis, Homo habilis and Homo erectus. There are other early hominids that are thought to be more distantly related Australopithecus africanu, Paranthropus aethiopicus, Paranthropus boisei and Paranthropus robustus.  The hominid that began to be dispersed around the globe was the bipedal Homo erectus. This species is thought to have evolved into Homo sapiens only 200,000 years ago, a blink of an eye in evolutionary terms.