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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

"A HOPEFUL MONSTER is an individual phenotypically discontinuous from the range of phenotypes of its population, and whose hopes of establishing a new lineage lie in finding a novel niche for which its monstrosity happens to be preadapted." A freak of extreme hybridization between species. https://lnkd.in/dDz5VYD View in LinkedIn

GHOST IN THE MACHINE. "The secret of complex life lies in the chimeric nature of the eukaryotic cell—a hopeful monster, born in an improbable merger 2000 million years ago, an event still frozen in our innermost constitution and dominating our lives today." A profound truth. http://www.pnas.org/content/112/33/10278.full View in LinkedIn

SINGLE LEAP. "If the origin of the eukaryotic cell was not a bottleneck, then it was probably a genuinely unlikely sequence of events, for it happened only once." http://www.pnas.org/content/112/33/10278.full View in LinkedIn