LOOKING DEEP INTO CELL 1: The Development Of Multicellular Organisms

           Development Of Multicellular organisms

As it was said and been discussed in the earlier sections that after earth was formed, the first form of life to exit were the first cell ( prokaryotes or bacterias) usually unicellular organisms then leading to the development of multicellular organisms. So in order to fully understand how multicellular organisms were been developed, we need to firstly understand how multicellular life evolved.

How Did Multicellular Life Evolved ? 

   According to research and observations, it was said and estimated that the first known single- celled organisms appeared on earth about 3.5 billion years ago, roughly a billion years after earth was formed. It tooks more complex form of life ( multicellular organisms) a longer period to evolved, because the Multicellular animals never appeared until about 600 million years ago.

  The evolution of multicellular life from simpler i.e. unicellular microbes was a crucial important moment in the history of biology on earth and has drastically reshaped the planets ecology. However, there is a question which i termed as the " Mystery about multicellular organisms" , why cell did not return back to single- celled life. how did multicellularity evolve? Did it evolve once or multiple times? How did cell make the transition from a single life cell to associating and cooperating with other cells such that they work as a single, cohesive unit? 

According to karl Niklas ( cornell university, ithaca, NY) a plant evolutionary biologist said multicellularity is a fundamental evolutionary achievement that is capable of mathematical description, and one that has occurred multiple times in different plants linage.

    However, no matter how it is defined, scientist agreed that multicellularity has occurred multiple times across many classes. Multicellularity has Evolved in at least 25 linages. Even when defined more strictly requiring that cells be communicated, connected and co operate in some fashion or another , we can say it has still notably evolved once in animals, thrice in fungi, six times in algae, and multiple times in bacteria. 

The evolution of multicellular organisms occurred multiple times and involved different developmental ' Motifs' , such as the chemistry of the ' glues' that makes cells to stick or glue together.

   "Unicellularity is clearly successful, unicellular organisms are much more abundant than multicellular organism and it has been estimated to have been in existence or around for at least an additional 2 billion years", said by lead study author Eric Libby which is a mathematical biologist at Santa Fe institute in new Mexico.

   However, in order for Multicellularity to evolve there are some certain sets of requirements that must be met, these include that the cell must adhere to, communicate with, and cooperate with each other and that cell must specialize in the functions ( i.e. not all cells do exactly the same thing, otherwise they would just be a group of cells or a colony). In other words to make this happen, cell must not reject each other, i.e they must be genetically compatible to some extent, this step is termed " alignment- of - fitness". This alignment - if - fitness requires a " bottleneck" or unicellular stage when the organism consist of just one cell, i.e a spore, zygote, or uninucleate asexual propagule. Why? This is necessary so that all subsequent cells shares similar genetic materials.