Essay Sample on Unraveling the Mystery of Multicellularity: Exploring Early Evolution

Introduction

Since time immemorial, the invention of multicellularity has been an exciting discovery that has pushed scientists into comprehending principles surrounding it. Scientists have studied the theories surrounding the early evolution in an attempt to understand why some of the unicellular organisms transformed into multicellular organisms. Emphasis has been on the reason for its occurrence - multicellularity. Gerhart and Kirschner (1997) presented their findings, which support the idea that multicellularity occurred because of the advantages gained. The two scientists claim that multicellular organisms can adequately protect themselves from the vagaries present in their habitats. As such, it was essential for the unicellular organisms to transition into multicellular organisms by producing their internal environment. Moreover, Dawkins also presented his argument claiming that multicellular organisms resulted because of the need for an effective mode of carrying genes from one generation to another - which could only be accomplished by building a complex soma which allows the germ plasma to survive. All these arguments presented by scientists lead to further interest in understanding the significance of multicellularity on earth, along with understanding the challenges that face multicellular organisms and how these challenges have been overcome over the evolution process.

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According to Bonner (1998), multicellularity primarily occurred because of the increased size of cells - a fundamental level of evolution that enabled possible transition. The earlier unicellular organisms increased in size gradually, and this enabled them to isolate themselves from the outside world and also gave the ability to protect genes essential for generation recurrence. Besides, the increase in size was subsequent, followed by the initiation of a division of labor, which got manifested in the form of cell differentiation. This supplemented the ability for organisms to become advantageous in their habitats selectively. Bonner presents his argument further by stating that the start, as well as evolution of multicellularity, initially occurred as an accident accruing from the increase in the size of the unicellular organisms.

An example is fetched from the mutation which prevents daughter cells from separating. In such a case, then, if the large cell bore advantages such as offering protection from an internal level, then natural selection would have maintained its state and prevented multicellularity from occurring. So it can be argued that the increase in size was the spearheading factor of multicellularity, which was later accompanied by other advantages brought about by the change. Evidence to support Bonner's contention is picked from the most compelling and simple observation of prokaryotes. Prokaryotes have evolved from being minute organisms and ultimately gave rise to the large mammals as well as angiosperms (Webb, Givskov, & Kjelleberg, 2003).

It can be deduced that the reason behind the appearance of multicellularity was initiated by the availability of ecological opportunities, which meant that competition seemed less when an organism was at the top (Grosberg & Strathmann, 2007). During the early stages of the evolution of organisms on earth, the competition was less because of the population factor. An increase in the population propelled organisms to change forms into complex forms to survive. It was an added advantage for multicellular organisms because of the increased selection opportunities that came along.

Multicellularity resulted in organisms that bore numerous cells, which provided an ability to perform specialized functions. Some of the familiar examples of multicellular organisms include plants, animals, and fungi. Alongside the numerous advantages that accompanied multicellular organisms, were the inevitable challenges. Some of these challenges interfered with the optimum functioning of these organisms. A perfect example is the development of thick body tissues by animals - meant to protect the vulnerable cells housed in the body. As such, these organisms need to source for oxygen for their cells. This resulted in the animals developing mechanisms to assist in sourcing oxygen for the cells. Animals developed effective circulatory systems that aided in transporting oxygen to the cells. This oxygen helps in breathing, implying that the animal can comfortably search for energy in food through scavenging. The other challenge faced by multicellular organisms is the increased need for energy to sustain their complex systems. As such, some animals resolved to feed on other organisms, including plants and other animals (Webb et al., 2003). It can be concluded that multicellularity was essential for organisms to survive in the continually growing population with limited resources. Multicellularity presented numerous advantages to the organisms, therefore, enabling for natural selection among them.

References

Bonner, J. T. (1998). The origins of multicellularity. Integrative Biology: Issues, News, and Reviews: Published in association with The Society for Integrative and Comparative Biology, 1(1), 27-36. Retrieved from https://onlinelibrary.wiley.com/doi/abs/10.1002/ (SICI) 1520-6602(1998)1:1%3C27: AID-INBI4%3E3.0.CO; 2-6

Gerhart, J., & Kirschner, M. (1997). Cells, embryos, and evolution: Toward a cellular and developmental understanding of phenotypic variation and evolutionary adaptability (No. 575.21 GER). Malden, MA: Blackwell Science. Retrieved from http://dannyreviews.com/h/Cells_Embryos.html

Grosberg, R. K., & Strathmann, R. R. (2007). The evolution of multicellularity: a minor, major transition? Annu. Rev. Ecol. Evol. Syst., 38, 621-654. Retrieved from https://www.annualreviews.org/doi/abs/10.1146/annurev.ecolsys.36.102403.114735

Webb, J. S., Givskov, M., & Kjelleberg, S. (2003). Bacterial biofilms: prokaryotic adventures in multicellularity. Current opinion in microbiology, 6(6), 578-585. Retrieved from https://www.sciencedirect.com/science/article/pii/S1369527403001504