Sta Hungry Stay Foolish

Stay Hungry. Stay Foolish.

A blog by Leon Oudejans

The complexity bias (2)

In 2015, “a first draft of the “tree of life” for the roughly 2.3 million named species of animals, plants, fungi and microbes—from platypuses to puffballs” was published (Phys-2015). In 2016, the “Tree of Life” was “dramatically expanded due to new genomic sampling of previously enigmatic or unknown microbial lineages” (Nature-2016). Humans are its latest addition (see right in picture).

In this Tree of Life, humans only represent less than 0.0000004% of all species. Volume wise, this % of humans must be much lower given the enormous volume of bacteria. As I’ve noted before, viruses are not included as there is still a debate whether viruses are alive – or not (my blogs).

The Tree of Life timeline shows an increase in complexity: from bacteria (some 3.5 billion years ago) to humans, some 2.8 million years ago.

This clear increase in complexity poses a dilemma: if simplicity is genius, why does (the timeline of) Life strive for complexity?

Obviously, this dilemma uses two assumptions: (1) simplicity is genius (part 1 of my blog), and (2) humans are more complex than bacteria or any other species (eg, BBCIndependent, Live Science). Let’s assume that both assumptions are valid.

The increasing complexity of Life includes – at least – three mysteries:
1. How did unicellular organisms (ie, Life) evolve? (eg, NatGeo-2010, NCBI)
2. How did multicellular organisms evolve? (eg, NASA-2017, Phys-2016Science-2014)
3. Why did multicellular organisms not return back to single-celled life? (NASA-2017)

Question 1 is still a mystery: “It appears that life first emerged at least 3.8 billion years ago, approximately 750 million years after Earth was formed. How life originated and how the first cell came into being are matters of speculation, since these events cannot be reproduced in the laboratory. Nonetheless, several types of experiments provide important evidence bearing on some steps of the process.” (NCBI)

NASA-2017 on question 2 and 3: “Unicellularity is clearly successful — unicellular organisms are much more abundant than multicellular organisms, and have been around for at least an additional 2 billion years,” said lead study author Eric Libby, a mathematical biologist at the Santa Fe Institute in New Mexico. “So what is the advantage to being multicellular and staying that way?”

NASA-2017: “The answer to this question is usually cooperation, as cells benefited more from working together than they would from living alone. However, in scenarios of cooperation, there are constantly tempting opportunities “for cells to shirk their duties — that is, cheat,” Libby said.”

To be continued in part 3 of this blog series.

Alive and Kicking (1985) by Simple Minds
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Note: all markings (bolditalicunderlining) by LO unless stated otherwise

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