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SO ENDS this further consideration of spider webs, and a prelude to the next weekend that largely deals with the subject of web geometry. Not only must webs be strong, and be composed of various silks, but they must also ensnare the prey with durable stickiness that does not dry out. The chemical manufacture and extrusion of these materials that polymerize outside the body from internal organs that operate at ambient temperatures and pressures is today beyond the capability of chemists; companies like DuPont and BASF have had to abandon this project. https://www.acs.org/content/acs/en/pressroom/presspacs/2014/acs-presspac-march-5-2014/synthetic-spider-silk-strong-enough-for-a-superhero.html View in LinkedIn

EVOLUTIONARY BOTTLENECK. "In this century, it is probably the evolution of mechanisms for importing necessary proteins into organelles that is taken as the most difficult, eukaryogenesis-limiting step." http://www.pnas.org/content/112/33/10278.full View in LinkedIn

CONTRARY FINDING. "Another is the recent discovery that the mealybug endosymbiotic β-proteobacterium Tremblaya harbors the γ-proteobacterial endosymbiont Moranella, on which it is absolutely dependent for complementation of many of its missing genes (it retains only 120!). This finding tells us that prokaryotes can acquire other prokaryotes as endosymbionts without first developing eukaryote-like phagotrophy." http://www.pnas.org/content/112/33/10278.full View in LinkedIn

INCOMPLETE SAMPLING. "If we, in principle, accept that interspecies lateral gene transfer (LGT) was involved in the assembly of such complex prokaryotic structures as the photosynthetic apparatus or type III secretion systems, we must also allow that the true histories of many nonmitochondrial eukaryotic cellular features are complex and reticulated, only appearing linear because of extinction and as yet poor sampling of available diversity." http://www.pnas.org/content/112/33/10278.full View in LinkedIn

SKELETONS IN THE CLOSET. "Unless eukaryogenesis was a once-in-a-universe cataclysmic miracle, in which all eukaryote-specific features appeared simultaneously and full-blown, there were very likely many contemporaneous lineages with all or some of those features." http://www.pnas.org/content/112/33/10278.full View in LinkedIn

SINGULAR EVENT? "It is often said that eukaryotes arose only once. What must really be meant by this is that there was but one last eukaryotic common ancestor (LECA) from which all contemporary living things that we call eukaryotes descend, and that if other lineages with similar features arose independently, they are now extinct or have not been found." http://www.pnas.org/content/112/33/10278.full View in LinkedIn

CARTOON FACTOIDS. "Writing for public audiences, and often even for themselves, biologists are not loath to make simplifying claims about uniqueness and importance that are rhetoric disguised as fact. Such generalizations serve purposes in the doing of science, but are often not themselves testable scientific claims and are subject to biases." http://www.pnas.org/content/112/33/10278.full View in LinkedIn

EXPECT THE IMPROBABLE. "However, combinatorial improbability is how evolution works: that eukaryotes arose is not unique in its uniqueness." http://www.pnas.org/content/112/33/10278.full View in LinkedIn

LAUGHINGLY IMPROBABLE. "The combinatorial stringing together of all of the steps between LECA and Macropus rufus (the red kangaroo), Trichomonas vaginalis, or Mozart is, indeed, laughably improbable. Surely, if life’s tape was rewound, none of these would recur." (LECA = ). http://www.pnas.org/content/112/33/10278.full View in LinkedIn

RIDDLES OF FORM "The waves of the sea, the little ripples on the shore, the sweeping curve of the sandy bay between the headlands, the outline of the hills, the shape of the clouds, all these are so many riddles of form." (D'Arcy Wentworth Thompson 1986-1948). https://lnkd.in/daEGKJJ View in LinkedIn