Life Begins


Chapter Four: Unicellular Life Forms on Shalimar


Shalimar offers a hospitable environment for life forms. The warm, even temperatures of the shallow seas provide conditions that support chemical reactions. Once rain had washed a rich mix of chemicals into the water, the stage was set for the beginning of life.

It is not known whether life appeared more than once on Shalimar. If there were a period without catastrophic meteor impacts, there might have been time for life to begin and spread over most of the warm parts of the planet, thus ensuring its own survival through occasional local meteor bombardments.

Life probably began with a sort of fermentation of the chemical mixture in the sea. Life forms somewhat similar to earthly viruses still exist, and cells with cell walls and nuclei exist in abundance. There are also cells without nuclei. Fortunately for the future of life on the planet, chloroplasts developed and were incorporated in cells to provide life forms with a sustainable source of energy. Photosynthesis resulted in the production of oxygen, which eventually changed the characteristics of Shalimar's atmosphere.

Cells on Shalimar reproduce by division. Sometimes the nucleus divides but the cell itself does not complete division into two individual cells. This doubling and sometimes redoubling of the chromosomes leads to variation among the life forms. Not all of these cells are viable, of course, but some survive. The proto-animals (cells that eat other cells) engulf other cells to devour them, but occasionally incorporate parts of the captive cell's DNA into their own. These stratagems have proven to be so successful that sexual reproduction is rare among these life forms.

On Shalimar, survival is challenged by the occurrence of unpredictable and possibly disastrous meteor strikes. Sudden temperature changes and extended periods of darkness may radically change the environment for the life forms on the planet. As there is no warning, and as the strikes do not occur at regular intervals, preparation for them is virtually impossible.

Microscopic life forms have become able to deal with sudden changes by quickly forming tough shell walls. The essential components of the cells remain inside these tough membranes while life functions become dormant. When warmth and light return, some of the cells are able to resume activity. The environment selects for life forms capable of shutting down quickly and surviving indefinite periods of dormancy.





© Elizabeth Anne Viau, 1996. This material may be used freely for instructional purposes but not sold for a price beyond the cost of reproduction. Please e-mail me at eviau@earthlink.net if you use this material. I'd be interested to know how it works for you!