A Mesophilic Origin of Life

A Mesophilic Origin of Life

Nearly all scientists agree that life on Earth began billions of years ago. Most will also agree that RNA appeared first and found a way to replicate itself, an essential step in the early stages of life. Without this ability of RNA, only short pieces of DNA could be copied and no enzymes could be created to copy longer strands which would be necessary for the formation of enzymes[1]. Beyond that, there is very little agreement about the origin of life, including what the original ancestor of all life was like. This has led to a significant amount of debating with very few answers. Scientists are still debating how life originated: was it a series of successive steps or a spontaneous gathering of the necessary materials? The problem with the second theory is that the odds of this happening are about the same as a tornado assembling a 747 aircraft in a junkyard.[2]

As of now, we still have to ponder whether the ancestor of all life, or LUCA, was a single being or a community of organisms sharing genes. Another question entails whether the last universal common ancestor (LUCA) dwelled in a hot-water environment or a cooler place, possibly near the surface of the ocean. The experts are split almost evenly on this question and both sides present convincing evidence for their side of the argument, but we will focus primarily on the side that believes that LUCA was not thermophilic, and, in fact, lived in a cooler surrounding. This cooler surrounding would have likely been near the surface of the ocean rather than in the vicinity of a thermal vent near the ocean’s floor.

The other side argues that Earth was warmer 3.5 billion years ago, when life is believed to have been spawned. This, c...

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...more evidence, especially in RNA sequences, until an answer can be established.

1] Smith, Szathmary 1999

[2] DeDuve, 1991

[3] Whitfield, 2004

[4] Levy, Miller, 1998

[5] Vogel, 1999

[6] Brochier, Phillippe, 2002

Works Cited

Brochier, C., and H. Philippe. 2002. A non-hyperthermophilic ancestor for Bacteria. Nature 417:244.

DeDuve, Christian. 1991. Blueprint for a Cell: The Nature and Origin of Life 100-105.

Levy, M., and S.L. Miller. 1999. The prebiotic synthesis of modified purines and their potential role the RNA world. Journal of Molecular Evolution 48:631-637.

Smith, John Maynard., and Szathmary, Eros. 1999. The Origins of Life: From Birth to the Origins of Language 1-14.

Vogel, G. 1999. RNA study suggests cool cradle of life. Science 283: 155-156.

Whitfield, J. 2004. Born in a watery commune. Nature 427:674-676.