In the Light of Evolution Volume IV: The Human Condition (2010) / Chapter Skim
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10 Footprints of Nonsentient Design Inside the Human Genome--John C. Avise
10 Footprints of Nonsentient Design Inside the Human Genome--John C. Avise
Pages 185-204
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From page 185... ...
-- the latest incarnation of religious creation ism -- posits that complex biological features did not accrue gradually via natural evolutionary forces but, instead, were crafted ex nihilo by a cognitive agent. yet, many complex biological traits are gratuitously complicated, function poorly, and debilitate their bearers.
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From page 186... ...
rather than to conscious engineering by a supernatural entity. in support of this contention, evolutionary biologists have dissected the genetic mechanisms and the probable step-by-step phylogenetic histories by which complex biological features [including some that Behe deemed to be irreducibly complex, such as the eye (Gehring, 2005; Ayala, 2007)
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From page 187... ...
Thus, the Act is designed either to promote the theory of creation science that embodies a particular religious tenet or to prohibit the teaching of a scientific theory disfavored by certain religious sects. in either case, the Act violates the First Amendment." 4 "iD [intelligent Design]
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From page 188... ...
Both a Creator God and natural selection are pow erful shaping forces that might be expected to have engineered beautiful functionality and efficiency into complex biological features, such as the human genome. The much greater challenge -- for proponents of iD and for scientists alike -- is to explain complex biological traits that operate inefficiently or even malfunction overtly.
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From page 189... ...
that are entirely amenable to critical scientific analysis. The Darwinian revolution did for biology what the Copernican revolution three centuries earlier had done for the physical sciences: permit the workings of the universe to be interpreted as reflecting natural laws that could be studied and tested via objective scientific hypotheses, observations, and experiments (Ayala, 2008; Ayala and Avise, 2009)
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From page 190... ...
however, the modern iD book with perhaps the biggest public impact is Darwin's Black Box (Behe, 1996) , in which biochemist Michael Behe coined the term irreducible complexity.
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From page 191... ...
Thus, "selfish DnAs" (e.g., many mobile elements) can persist and proliferate in a genome without enhancing the well-being of a host population.
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From page 192... ...
, the goal of which is to use rapid DnA sequencing to gather numerous human genomic sequences. such investigations are merely the latest generation of scientific inquiries into human genetics and biochemistry, which extend back about a century.
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From page 193... ...
A recent edition of MMBID includes more than 6,000 pages in four volumes. in 255 chapters, each on a different heritable disorder or suite of associated genetic dis orders, leading biomedical experts encapsulate current knowledge about the molecular mechanisms underlying inborn human diseases.
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From page 194... ...
, from year 1 to puberty, from puberty to 50 years of age, or in seniors. Approximately two-thirds of the genetic defects described in MMBID shorten human life span, and about three-quarters of these cause death before the age of 30 years.
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From page 195... ...
An apologist for the intelligent designer might be tempted to claim that such deleterious mutations are merely unavoidable glitches or sec ondary departures from a prototypical human genome that otherwise was designed and engineered to near perfection. As i will briefly describe in the next two sections, however, this excuse would be untenable, because all human genomes are also littered with inherent (endogenous)
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From page 196... ...
do just fine without split genes and introns, as do the mitochondrial genomes within human cells; thus, there is no universal biological exigency that these features exist. Finally, the human nuclear genome would have ample room to house nonsplit genes for all the proteins it needs (including those that are now alternatively spliced)
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From page 197... ...
in a broad definitional sense, the genetic regulation of protein-coding genes can also occur at any posttranscriptional stage of protein produc tion, including premrnA editing, the exportation of mature mrnAs from the nucleus, differences in the stability and transport of mrnA molecules after they have reached the cytoplasm, factors impinging on the trans lation process by which polypeptides are constructed from mrnA on ribosomes, polypeptide assembly into functional proteins, and posttrans lational protein modifications or degradations. Many of these regulatory mechanisms involve complex biochemical pathways, and, collectively, they require major expenditures in cellular effort and molecular materials.
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From page 198... ...
The various mechanisms described here thus help to orchestrate how particular genes and their protein products are expressed within a cell. Many additional routes to gene regulation exist, such as how nucleic acid sequences are spatially organized and packaged into chromatin fibers and chromosomes, how DnA molecules are complexed with histone proteins, and the pattern in which cytosine bases in DnA sometimes are modified via chemical methylation.
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From page 199... ...
occasional errors in gene regulation and surveillance are to be expected in any complex contrivance that has been engineered over the eons by the endless tinkering of mindless evolutionary forces: mutation, recombination, genetic drift, and natural selection. Again, the complexity of genomic architecture would seem to be a surer signature of tinkered evolution by natural processes than of direct invention by an omnipotent intelligent agent.
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From page 200... ...
however, the intellectual challenges for iD go much deeper. Considering the critical role of cellular energy production in human health and metabolic operations, why would an intelligent designer entrust so much of the production process to a mitochondrion, given the outrageous molecular features this organelle possesses?
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From page 201... ...
in truth, however, structural genes have complex internal structures in which the exons typically are like small islands in much larger hereditary rivers of noncoding introns and regulatory regions. An even bigger surprise came with the discovery that the vast majority of human DnA exists not as functional gene regions of any sort but, instead, consists of various classes of repetitive DnA sequences, including the decomposing corpses of deceased structural genes and legions of active and retired transpos able elements.
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From page 202... ...
Mobile elements have the potential to cause human diseases by sev eral mechanisms. When a mobile element inserts into a host genome, it normally does so at random with respect to whether or not its impact at the landing site will harm the host.
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From page 203... ...
. Despite the relatively recent discovery of mobile elements, the list of genetic disorders associated wholly or in part with their activities already is long.
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From page 204... ...
Traditional placement of evolutionary biology as the oddman-out to the spheres of mainstream religion and iD in many philosophical discourses about the human condition. (Lower)
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