Is There Purpose in Biology?  The Cost of Existence and the God of Love. By Denis Alexander, Chapter 2: Biology’s Grand Narrative | 4/24/2019 | Mike the Geologist
melanie7 (Posted by) Level 3
We are reviewing the book: Is There Purpose in Biology? The Cost of Existence and the God of Love. By Denis Alexander. Chapter 2 is Biology’s Grand Narrative. In this chapter Alexander asks the question: “What happens when we look at the general features of biological evolution – the overall “grand narrative” – in the light of the claim that it is necessarily purposeless? What do we actually observe?” His first chapter point is that we observe increased complexity over time. The first 2.5 billion years things rarely got bigger than 1 millimeter across. There were no birds, no fish in the sea, no animals wandering around. Gradually, through photosynthesis and other factors complex and not completely understood, the oxygen in the atmosphere built up to the 21% levels of today. Another major transition came with the development of multicellularity. Once multicellularity evolves, there is a huge scope for increased specialization in cell functions and in the construction of organs. There is good evidence that multicellular forms of life have evolved many times independently from all three forms of single-celled life, the bacteria, the archaea (archaea constitute a domain of single-celled microorganisms. These microbes are prokaryotes, meaning they have no cell nucleus.), and the eukaryotes (an organism consisting of a cell or cells in which the genetic material is DNA in the form of chromosomes contained within a distinct nucleus).

Figure 1 from the book gives the example that Alexander is talking about. Multicellular volvocine algae first started appearing 220 million years ago. Somewhere at some time a single –celled alga divided and the two daughter cells remained embedded in a chemical known as a glycoprotein. So from now on this chemical binding meant that different cells had to contribute to the common good, at least as far as that organism...
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