Knead me not into temptation

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

Like other simple life forms, yeasts such as Saccharomyces cerevisiae are fully self-contained within one microscopic cell. S. cerevisiae cells are round and, providing they are well nourished with carbohydrates, spend most of their life-cycle reproducing vegetatively by growing buds. Buds separate from the parental cell when they reach a certain size in order to follow an individual pattern of growth. Upon maturity these too can start budding; each cell produces about thirty progeny. The loss of the bud leaves a scar on the parental cell that can be visualised with fluorescent dyes or electron microscopic techniques. The pattern and number of scars can reveal a lot about the condition and age of the yeast cell. Some yeasts do not reproduce by budding but by forming a cross-wall rather like the mitotic cell division observed in higher eukaryotes. Schizosaccharomyces pombe or fission yeast is an example of this. It divides in a similar way to human cells and therefore is used as a model system to study many human diseases, especially cancer.

Yeast cells stained with calcofluor white dye and observed under a fluorescent microscope. Newly budded cells take up less dye. Small rings on cell surfaces are budding scars. Image:bio+ve

The concept that living organisms produced leaven wasn’t seriously considered until Erxleben, in 1818, proposed that leaven and barm consisted of living vegetative organisms responsible for fermentation. Prior to this, in 1680, Leeuwenhoek, with his early microscope, observed yeast cells in fermenting beer. He referred to most of these single-celled creatures as animalcules because they were believed to be immature forms of larger animals. These first observations of microscopic cells were not further investigated for another century. Leeuwenhoek’s contemporaries were largely preoccupied with the argument centred on spontaneous generation, a belief that animals could materialise from other living or mineral things. Before groundbreaking experiments by Louis Pasteur in the mid 19th Century, which illustrated that excluding particles from sterile broth prevented contamination by microbes, many theorists believed in spontaneous generation.

Different theories and speculations concerning the creation of organic things occur in every religion, as most feel that the complexity of the natural world could not have arisen by chance. Many investigators began to challenge the image of creation as depicted in the Bible. Perhaps the most compelling of these arguments was the theory of natural selection presented by Charles Darwin in the mid 19th Century. His book entitled the Origin of Species created tensions between the Church and Science because it questioned a popular and largely excepted image of creation.

Religious devotees perhaps saw Science as being not only a threat to their faith but to their social acceptance and respect. Science innovation threatened to ridicule the basis of their fundamental beliefs and values. It is therefore understandable that there was a need to retain Biblical teachings in some form. In the 19th Century, the paradigm shift that was rapidly evolving Science was too extreme to evoke an equally rapid change in religious faith. In order to fully commit to a belief requires a great deal of conviction. This conviction can be impenetrable leading believers to imagine that an evil being is responsible for any deviancy from a steadfast commitment. Any element of uncertainty in religious belief seems to lead to the evolution of new religious theories to give meaning to situations that are too difficult to comprehend. In the New Testament an interesting method is used to quell sceptics and doubting critics. Individuals who questioned the ideals proposed by Jesus were thought to be influenced by the Devil:

Jesus is tempted by the Devil. Mosaic from Monreale Cathedral. Image by Sibeaster

After spending forty days and nights without food, Jesus was hungry. Then the devil came to him and said, “If you are God’s Son, order these stones to turn into bread.”
But Jesus answered, “The scripture, says, Man cannot live on bread alone, but needs every word that God speaks.”
[Matt. 4.1-11; MK. 1.12-13; Lk. 4.1-13]

This  not only discourages doubt from those with religious faith but also prevents others from persuading them away from their convictions. It is not surprising that scientific hypotheses that question religious beliefs are subject to contention.

…spontaneously generated beer

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

One big difference between scientific and theological theory is that scientific hypotheses result from physical rather than spiritual observations, so therefore can be challenged by subsequent experimental investigation or  re-examination. For instance, many of Mendel’s laws and hypotheses, concerning genetic inheritance, have withstood this kind of scrutiny. In contrast, the theories of spontaneous generation presented by Antoine van Leeuwenhoek and several of his contemporaries, in the 16th century, were eventually disproved.

Leeuwenhoek was a draper, chamberlain and wine-gauger who specialised in making high quality magnifying lenses. He constructed an early form of microscope with a hand-ground lens that, although technologically advanced for that era, could only magnify specimens by about 250 times their natural size. Anyone who has observed pond water in a microscope during a science class will be aware that it contains a myriad of darting and spinning life forms of every description. These would have appeared astounding to the uninformed mind; it would naturally be assumed that these miniature life forms would eventually grow into something much larger. Leeuwenhoek used his apparatus to observe blood, serum, semen and other body fluids and found in it what he called ‘animalcules’. He perceived that animalcules had arisen spontaneously and were in fact microscopic extrapolations of larger entities. Most notably he imagined that spermatozoa were tadpole-like cells that contained their own circulatory and nervous systems.

Animalcules observed by Anton van Leeuwenhoek, c1795

In the latter part of the 16th century a number of scientists, including Leeuwenhoek and Nicolaas Hartsoeker, published drawings of sperm which they believed to be miniature versions of humans a theory known as  ‘preformation‘ .  In these drawings, miniature human foetuses were folded as they are observed in the uterus, but within the heads of sperm. Although, through lack of knowledge and the limitations of their equipment, these researchers were incorrect they attempted to give an intellectual framework to what they observed. Subsequent curiosity and the art of experimentation led to the abolishment of these theories but the discovery of microbes by Leeuwenhoek has cemented his name in scientific history.

Human forms in sperm drawn by Hartsoeker in 1695.

Incidentally, Leeuwenhoek, it seemed, was also interested in the properties of fermentation. Amongst the many microscopic structures he discovered were globular bodies, sometimes oval or spherical shaped, in droplets of fermenting beer. These were the first known microscopic observations of yeast cells.