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POST 3

5-02-2014

 

CONTENTS:

THE OTHER BANGS

    PREBIOTIC CONDITIONS

    THE FIRST BEING

READINGS

………………………………………………………………………………………………………………….

THE OTHER BANGS

On the long trek from the BIG BANG to today there have been a number of significant steps taken. Nick Lane (2009) selects ten of them for close study. He calls them the great inventions of evolution. His choices are:

  1. The Origin of Life
  2. DNA
  3. Photosynthesis
  4. The Complex Cell
  5. Sex
  6. Movement
  7. Sight
  8. Hot Blood
  9. Consciousness
  10. Death

Of these evolutionary giant steps there are two that stand out in my view as special cases. Both “The Origin of Life”, with the arrival of the first living being and “Consciousness”, with  the arrival of creativity stand out as occurring as the result of an all or nothing change. I think that the arrival of The Complex Cell is the other one to which I would give a guernsey and more of that later.

It seems impossible for there to be an almost-living being or an almost-conscious being. In my view the arrival of the first being that was truly alive and the first being that was truly conscious must have happened as a result of an emergent phenomenon. Most of evolution’s inventions occurred as a result of the incremental changes resulting from natural selection. This is the process by which heritable traits make it more likely for an organism to survive and successfully reproduce and become more common in a population over successive generations. It is a key mechanism of evolution.

An emergent phenomenon occurs when a situation reaches some particular tipping point. The classical example is the pile of dry sand formed as you empty successive handsfull of sand onto a sandcastle. Eventually you reach a point when small avalanches form and slide down the side of the sandcastle. It is true that it would not happen but for the buildup of the handfulls of sand but the little avalanche happens where there was no avalanche before. Similarly I maintain that the first living being and the first conscious being emerged by such a phenomenon. There was plenty of slow evolving happening before-hand to allow this “avalanche” to occur but the significant change happened only once the groundwork had occurred. The prebiotic condition in the primeval swamp or the submarine blue-smoker had evolved so that life could happen and the pre-human brain had evolved so that consciousness could happen.

I cannot see that any of the other of Lane’s “inventions” required this emergent phenomenon. It is for this sort of reason that I have chosen these two events as so significant in the story I tell.

PREBIOTIC CONDITIONS

As with the BIG BANG there is a system-shift or emergent phenomenon when a living being happens. There is no gradient between the two states of living and non-living. Both before and after there was a living thing, there was plentiful opportunity for changes of an incremental nature that eventually led through a long detailed process of response to local environmental changes. Beforehand there were opportunities of a quite different kind. Change had been occurring before-hand or else things could never have got to the starting point for life to begin.

The study of how life on Earth could have arisen from inanimate matter is called abiogenesis. It is the study of how the first nucleic acids came into existence. The environment before life began was not a stable chemical mix. From the time of the Big Bang matter had been changing as a result of the interactions between sub-atomic particles, atoms and molecules due to changes in conditions including gravitation, radiation, pressure, temperature and chemical evolution.

An aggregate of abiotically produced organic molecules surrounded by a membrane or a membrane-like structure is called a protobiont. Protobionts exhibit some of the properties associated with life, including simple reproduction, metabolism and excitability, as well as the maintenance of an internal chemical environment different from that of their surroundings.

These prebiotic conditions may be formed spontaneously, in circumstances similar to the environment thought to exist on an early Earth. Some experiments have been conducted which formed liposomes and microspheres with membrane structure similar to the phospholipid found in cells. The formation of RNA may have been the critical link in the process.

A recent paper by Powner et al (2009) on the subject of RNA formation from a number of “plausible prebiotic feedstock molecules” adds weight to the case for this pathway to life’s beginning.

The nature of this change is such as to be described as a system change rather than an incremental build-up.

Once the system change occurred the protobiont is called a biont which is a discrete unit of living matter, an individual organism. The term is then used to apply to all living matter whether unicellular or multicellular. The path from the first Biont to current living organisms is the story of evolution by natural selection.

THE FIRST BEING

The first being must have had certain identifying characteristics to enable it to have moved on.

It must have had a cell wall (no matter how primitive or simple – perhaps a “skin” of fatty material. This was needed to give it. Prebiotic matter had some of the characteristics of life, namely reproduction, metabolism and excitability. The new cell must have had these same traits plus an ability to survive in its new living form.

  • individual integrity
  • Survivability
  • Development (metabolism)
  • Reproduction
  • Excitability (sensitivity)

It had to survive or it would not have become the progenitor of all other life forms. It occupied space and time. Its environmental space was affected by change and while the space may have been limited and the change may have been passing at a geologically slow rate, it still had to be able to adjust to change. The rate of development and of reproduction may have been slow but the changes in the environment were probably also slow.

Once the first cell was operational and it commenced reproduction there was an opportunity for evolution by natural selection to occur.

Excitability or sensitivity or as some biologists prefer to call it, irritability, lies at the origin of preference selection and thus of choice and that concept will lead us on to the ethics of human behaviour. In the beginning (of life) there was a reaction (response) – because survival was dependent upon it.

READINGS

Vaccination and alternative lifestyles shows that there is hope for the children of trendy alternative parents.

Black holes still exist; we just know more about them. Hawkins has not really dismissed black holes.

Don’t let denial get in the way of a good science story by Ian Lowe tells us something of the problems of marketing Science.

Will The Overselling Of Global Warming Lead To A New Scientific Dark Age? Patrick Michaels also tells us of the marketing problem.

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