c. 4.6 billion years ago (“bya”)
Many into their structures. also incorporate silica, and those are among the few life forms that use silicon, although it is one of . Diatoms seem to gain , and plants seem to have structural advantages, but it is thought that plants also used silica for a defensive measure, as it helps make plants unpalatable. Eating plants full of silica structures, called , is like chewing sand. This is particularly true with grasses, as phytoliths make chewing them a tooth-wrecking process, particularly for ruminants and their thorough chewing. Grazing herbivores have heavily enameled hypsodont teeth (also called high-crowned teeth) to . In North America, hypsodont herbivores proliferated while those without that heavy enamel (also called low-crowned teeth), which were browsers instead of grazers, declined. By about nine mya, North American browsers had largely vanished and grazers dominated the new grasslands. Earth kept cooling and drying, and fewer than seven mya, steppe vegetation began replacing savanna-like grasslands, and forests were decimated. This led to the greatest mass extinction in pre-human North America in the Cenozoic Era, as many species of horses, mastodonts, bears, dogs, and small predators went extinct, as well as mice, beavers, and moles. Asia and Africa were hit similarly, although not quite as hard as North America seemed to be, but South America and Australia hardly seemed affected at all. New Zealand’s surrounding seafloor changed from warm-water communities to the Southern Ocean communities that it has today.
Organisms begin to capture chemical energy.
The press are interested in selling papers and the TV companies wantto gain viewers. Threat of world-wide disaster makes a good story, andthe statements and actions of politicians together with great increasein scientific publications gave global warming an apparent authority. Themedia began to proclaim the worst imagined horrors. For example, massivefloods were predicted due to melting of polar ice. and one UK TV programmewent so far as to assert that the polar bears would die out because theirhabitat would melt. The public rely on the media to provide them with theirinformation, so they came to believe the global warming scare because theywere only given one side of the story. Politicians respond to public concern,so the politicians actions began to gain popular support.
Newton invented his , but the science of energy did not develop until more than a century after the steam engine appeared. I have heard physicists question whether owed more to the steam engine than the converse. The so-called began their formulation with , which is actually the third of the four laws of thermodynamics and is the earliest enunciation of the concept of , and . A generation later, European scientists began taking his work further. The great works of , , and friends formed the foundation of today’s science of energy, and many basic terms of today’s energy science were named after the pioneers of energy technology and theory, including , , , , , , , , and .
First large-scale energy users.
I have encountered numerous technologies that theorists denounce as “,” empiricists ignore as if they did not exist, while the inventors are not exactly sure why their inventions work, but only know that they do. Such inventions often threaten to upend the very foundations of scientific disciplines, which is primarily why they have been ignored as they have, if they are not actively suppressed. When their breakthroughs threatened the dominance of the industrial/professional rackets, then the .
First complex ecosystems appear.
In , the tests have all had their issues and refinements. The equipment has become more sophisticated, problems have been resolved, and precision has been enhanced. While there are continuing controversies, dating techniques have advanced just like many other processes over the history of science and technology. In 2014, dates determined for fossils and artifacts are generally only accepted with confidence when several different samples are independently tested and by different kinds of tests, if possible. If , , and other tests produce similar dates, as well as , , current measurements of , along with genetic and other evidence introduced in the past generation, those converging lines of evidence have produced an increasingly robust picture of not only happened, but .
Concentrated application of muscle energy.
In the 1990s, I found the dating issue enthralling and saw it assailed by fringe theorists and by . A couple of decades later, I reached the understanding that, like all sciences, dating has its limitations and the enthusiasm for a new technique can become a little too exuberant, but dating techniques and technologies have greatly improved in my lifetime. Dating the , and using 100,000-year increments to place the dates, may seem a conceit, thinking that scientists can place that event with that precision, but over the years my doubts have diminished. When and can be tested, and the findings support not only Earth’s age previously determined by myriad methods, but also support the prevailing theories for the solar system’s and Moon’s formation, call me impressed. Controversies will persist over various finds and methods used, and scientific fraud certainly occurs, but taken as a whole, those converging lines of independently tested evidence make it increasingly unlikely that the entire enterprise is a mass farce, delusion, or even a conspiracy, as many from the fringes continue to argue. There is still a , and it is not a parody. I have looked into fringe claims for many years and few of them have proven valid; even if many were, their potential importance to the human journey was often minor to trifling. As the story that this essay tells comes closer to today’s humanity, orthodox controversies become more heated and fringe claims proliferate.