The Age of the Essay - Paul Graham
But the branch of the that readers might find most interesting led to humans. Humans are in the phylum, and the last common ancestor that founded the Chordata phylum is still a mystery and understandably a source of controversy. Was our ancestor a ? A ? Peter Ward made the case, as have others for a long time, that it was the sea squirt, also called a tunicate, which in its larval stage resembles a fish. The nerve cord in most bilaterally symmetric animals runs below the belly, not above it, and a sea squirt that never grew up may have been our direct ancestor. Adult tunicates are also highly adapted to extracting oxygen from water, even too much so, with only about 10% of today’s available oxygen extracted in tunicate respiration. It may mean that tunicates adapted to low oxygen conditions early on. Ward’s respiration hypothesis, which makes the case that adapting to low oxygen conditions was an evolutionary spur for animals, will repeatedly reappear in this essay, as will . Ward’s hypothesis may be proven wrong or will not have the key influence that he attributes to it, but it also has plenty going for it. The idea that fluctuating oxygen levels impacted animal evolution has been gaining support in recent years, particularly in light of recent reconstructions of oxygen levels in the eon of complex life, called and , which have yielded broadly similar results, but their variances mean that much more work needs to be performed before on the can be done, if it ever can be. Ward’s basic hypotheses is that when oxygen levels are high, ecosystems are diverse and life is an easy proposition; when oxygen levels are low, animals adapted to high oxygen levels go extinct and the survivors are adapted to low oxygen with body plan changes, and their adaptations helped them dominate after the extinctions. The has a pretty wide range of potential error, particularly in the early years, and it also tracked atmospheric carbon dioxide levels. The challenges to the validity of a model based on data with such a wide range of error are understandable. But some broad trends are unmistakable, as it is with other models, some of which are generally declining carbon dioxide levels, some huge oxygen spikes, and the generally relationship between oxygen and carbon dioxide levels, which a geochemist would expect. The high carbon dioxide level during the Cambrian, of at least 4,000 PPM (the "RCO2" in the below graphic is a ratio of the calculated CO2 levels to today's levels), is what scientists think made the times so hot. (Permission: Peter Ward, June 2014)
September 2004 Remember the essays you had to write in high school
Energy and the Human Journey: Where We Have Been; …
The greatest scientists readily admitted that the theories and data of physics, that hardest of the hard sciences, drew highly limited descriptions of reality, and those scientists were usually, to one extent or another, . If textbook science falls far short of explaining reality, what can be said within its framework that is useful? Plenty. Our industrialized world is based on textbook science and feats such as putting men on the Moon were performed within the parameters of textbook science. With the waning of overspecialization and overreliance on reductionism in the last decades of the 20th century, multidisciplinary works have proliferated and will tend to dominate the references for this essay. I have found them not only very helpful for my own understanding, but they are appropriate references for a generalist essay. I have also avoided scientific terminology when feasible. For example, I use “seafloor” instead of “,” and if a non-specialized term will suffice for a scientific concept, I will often use it.
Religion is an almost universal institution in human society
is complex, but the preceding presentation is largely adequate for this essay’s purpose, while it can be helpful to be aware that the physics behind FE and antigravity technologies will probably render the Standard Model obsolete. If FE, antigravity, and related technologies finally come in from the shadows, the elusive may come with them, and the Unified Field might well be consciousness, which will help unite the scientist and the mystic, and . But that understanding is not necessary to relate the story that White Science tells today of how Earth developed from its initial state to today’s, when complex life is under siege by an ape that quickly spread across the planet like a cancer once it achieved the requisite intelligence, social organization, and technological prowess.