Three thousand million years

Let us imagine that an extraterrestrial civilization wanted to study our planet s life and decided to send a spaceship on Earth once every million years. For at least 2000 times, the answer would have always been the same The dry lands are completely sterile, and in the seas there are only colonies of bacteria. After that, the dispatches would have been slightly different Now there are small amounts of oxygen in the atmosphere, and the seas are also inhabited by bigger cells which 

This is precisely how we reconstruct (with far fewer samples) our planet s past. The first cells appeared on Earth more than 3.5 billion years ago, and the first animals arrived just over 500 million years ago. For 3 billion years, in other words, the Earth was inhabited only by micro-organisms. Three billion years are simply inconceivable to our mind. We can try alternative expressions such as three thousand million years or three million millennia, but none of these wordings can give us even a feeble idea of the immensity of that expanse of time. 

The only thing about which there seems to be a general agreement is that cellular evolution was incredibly long and incredibly slow it appears that very little happened in the first 3000 million years, and that the real story of life started in earnest only at the end of that enormously boring aeon, with a spectacular explosion of creativity. Things, of course, could have gone precisely that way, but let us try to look back from a different point of view. 

An army, a crowd, a nation, or other human societies, can be very complex structures, but none of them is as complex as a single individual human being. And the same is true for all animal societies a beehive or an ant-hill, for example, is a far simpler system than any individual insect. And if it is true that individuals are more complex than their societies, then it could be that single eukaryotic cells are more complex than societies of eukaryotic cells, i.e. multicellular organisms. And this in turn would explain why unicellular evolution had to be so much longer than multicellular evolution. 

This is an attractive hypothesis, but it does have a weak point. It is true that societies such as armies, crowds, beehives and ant-hills, are simpler than individuals, but this happens because they are made of individuals which are physically separated. The same does not apply to animals and plants, where individual cells gave up their physical 

---

Microbial cells were the first living cells on earth. They appeared about three and a half thousand million years ago as the starting point of the evolution of life on our planet. Microfossils that have been found in flint and certain other very fine sediments are regarded as direct proof of such early life — of cyanobacteria, for example, which probably formed a blue-green slime in the littoral regions of lakes close to volcanoes. 

Robert Jastrow, the head of NASA s Goddard Institute for Space Studies, called this the most powerful evidence for the existence of God ever to come out of science. Other amazing parameters abound. If all of the stars in the universe were heavier than three solar masses, they would live for only about 500 million years, and life would not have time to evolve beyond primitive bacteria. Stephen Hawking has estimated that if the rate of the universe s expansion one second after the Big Bang had been smaller by even one part in a hundred thousand million million, the universe would have recollapsed.The universe must live for billions of years to permit time for intelligent life to evolve. On the other hand, the universe might have expanded so rapidly that protons and electrons never united to make hydrogen atoms. 

Mammoths, Mammuthus primigenus, roamed huge areas of the globe for four million years. The last mammoths died out at the end of the last Ice Age, about seven thousand years ago. Contrary to popular belief, elephants are not descended from mammoths but are from the same species as mammoths, and so are cousins. The first to arrive in Europe probably did so about three and a half million years ago. 

Titanium is an element of group 4 of the periodic table. It is in the same group as zirconium and hafnium. It has a high similarity to silicon which was the same group in the old periodic table. Titanium exists in 5600 ppm in the Earth s crust [1], it is the fourth largest element after iron, aluminium and magnesium as common use metal. The titanium deposits are approx. 340 million tons or more [2], The span of life as a metal resource is three thousand years or more, the ranking of the life of resources as practical metals is the second after iron. 

Taking these estimates, the WASH-740 authors made an admittedly highly speculative projection. Using the most pessimistic estimate for the worst accident (fission-product release outside the containment), and assuming that one hundred reactors were in operation, and further assuming that each accident would kill three thousand people, they extrapolated a figure of one chance in fifty million per year that a person would be killed by a reactor accident. For comparison the authors cited the probability of a person in the United States being killed by an automobile accident as about one in five thousand per year. ... 

The Late Devonian was a time of profound evolutionary and environmental change associated with the Frasnian-Famennian Biodiversity Crisis, including reduction in speciation rates, increased extinction rates, rampant species invasions, and ecosystem restructuring (Sepkoski, 1986 McGhee, 1996 Droser et al., 2000). The biodiversity crisis may have lasted as long as three million years with a final pulse of more severe extinction in the last few hundred thousand years of the Frasnian. To unravel the faunal dynamics of this complex crisis, it is critical to understand both the spatial and temporal patterns associated with biodiversity decline. 

There is another aspect of photosynthesis that we should all appreciate. That is, the health of our biosphere and our atmosphere is totally dependent on the process of photosynthesis. Every three hundred years all the CO in the atmosphere is cycled through plants. Every two thousand years all the oxygen, and every two million years all the water. Thus three key ingredients in our atmosphere are dependent on cycling through the process of photosynthesis. 

Even after 10 years and nearly 700 projects, the two thousand employees continued to identify high-return projects. The contests in 1991, 1992, and 1993 each had in excess of 100 winners, with an average return on investment of 300 percent. Total energy savings to Dow from the projects of those three years exceeded 10 million, while productivity gains came to about 50 million. 

---