Life on Earth flow chart

Figure 32. Life on Earth

Paleontologists are geologists specialized in the study of remains of past life - fossils. While some dig up dead dinosaur bones (sometimes reporting leafy stomach contents, three-valved hearts, lizard-type skin and rare feathers), others spend their careers peering down microscopes at the tiny ones - the microbes, the foraminifera, diatoms, dinoflagellates, algae, amoebas, nematode worms and a truly endless supply of new species of Monera, all described at 500X.

Life on Earth is perplexingly diverse. It's hard to even get a handle on the diversity. One book that I find fascinating, besides Wilson's book 'The Diversity of Life' is Lynn Margulis and Karlene Schwartz, 'Five Kingdoms,' second edition, where they attempt to categorize all of life into some 70 phyla. That's a tall order, especially when they come to the bacteria. Basically, the species concept is invalid with bacteria because they continually have sex with different species, mixing up their tiny little genomes beyond recognition. And so new kinds of diseases appear continually like ebola, the new 'staphs' and TB. Also, go to Yellowstone Park and look into the pools of water at 180 deg F at all the colorful bacterial mats that live there happily. I'm not even going to mention the viruses.

For many years the experts have been saying that there are about 2 million classified species of life on Earth. 250,000 plants, 45,000 vertebrates, etc. Arthropods (insects, spiders, lobsters, crabs, houseflies, kitchen cockroaches, etc) account for a great percentage - and the most diverse arthropod group of all is the beetles, with some 400,000 classified kinds. There are ten times more kinds of beetles than all vertebrates combined! Now that we can classify by automated DNA work, the numbers are skyrocketing. Just announced that there may be 1.8 million kinds of fungi (mushrooms, etc). The kicker is that we estimate that the vast majority of species have never been fossilized, so that we may only recognize 0.1% or less of everything that has ever lived. Preservation by fossilization is in fact a very rare process. This is like trying to understand a 1,000-page book written in an undeciphered script by studying the sole remaining half-page. Lots of luck!

The origin of life. Look at the complexity of Figure 32. Those who peer at this kind of diagram long enough always ask how it happens, the base rules of change, and where life comes from. Nobody knows. NOBODY. Two resounding factoids: The oldest continental rocks known on Earth, called the Isua Complex on the shores of SW Greenland, contain definite signs of a primitive 'archybacteria' that lived in hot springs and deposited chemical mats of iron oxide (hematite) upon sandy shores of the early world ocean, dated to about 3,800 m.y.. These guys still blow out of deep sea 'smoker' hot spring vents. See the photo in the photo section. These bacteria are unlike all other life on Earth in that their metabolism lacks an otherwise universal energy circuit called the Krebs cycle. They can live in high-pressure water at 650° F in the lab! We do low-fire ceramics at that temperature in electric kilns. Where did theses bifs (banded iron formations) come from? How did they get here so very early?

The next resounding factoid is that Darwinian evolution - change by tiny increments over very long times coupled with natural selection (survival of the fittest) - cannot easily explain the bouts of very fast appearance of many new species of very different character at the times of the severe mass extinctions, pointed out by Niles Eldridge & Stephen Jay Gould in 1972, when they invented a name to account for this discrepancy - 'punctuated equilibrium,' when major new groups appear in a flash. The eye, and the ability of flight through the air have been 'invented' or 'discovered' several times independently, it seems. How can this happen? The eyes of mollusks, fish, and arthropods showed up independent of one another. The human eye is derived from amphibians, fish, and tracking back through Amphioxus, and garden worms.


The next-oldest life form, from 3,500 m.y. ago are the stromatolites, green mushroom layered masses growing in tropical shallow lagoons, and found in most all Archean complexes on all the continents - described in Section 9, but with two giant step-ups in complexity - they were the first to use the same Krebs cellular energy cycle that powers redwood trees, brine shrimp, mushrooms, sharks and humans, and they were doing photosynthesis, converting sunlight into sugars, and throwing out waste oxygen into the atmosphere, clearing the path for animal life. They still inhabit the planet in intertidal warm seas, in spots like Baja California and Shark Bay, western Australia. They are even adapted to deserts like southern California and thrive during summer floods. The first eukaryotic organisms (with well-defined cellular nuclei) are represented by Grypania spiralis (Figures 34 & 35) at 2,000 m.y., a marine floating colonial algae, fossils found in Ontario Canada (see photo section). The oldest fossils of land creatures are spiders and scorpions (and mites) at about 450 m.y.. But what did they eat? - their modern descendants are all carnivorous. Possibly their prey species did not fossilize easily. The history of dinosaurs and birds is in convolution--new evidence indicates that birds may be as old as dinosaurs, or older. Their evolutionary paths are quite questionable - they are definitely closely related. As it stands, the oldest mammals (some furry shrew-like insect-eaters) were contemporaneous with the first dinosaurs, but were obviously out-competed, quivering in the shadows of the reptiles. Triassic beds in Montana display both kinds of animals. Another unsettled issue is the longevity of the flowering plants, the angiosperms. Their predecessors, the gymnosperms or conifers (pines, hemlocks, junipers, etc) showed up in middle Permian time (280 m.y.). Flowering plants, including the palms, were commonly fossilized beginning only in the middle Cretaceous (120 m.y.), but a new report of a true flower preserved in middle Triassic beds (220 m.y.) throws new light on a potentially far longer history. There is a fossilized bee colony in Arizona's Petrified Forest (220 m.y.) that was built into a large conifer tree hollow, and it was always a question of just what they were pollinating. Pines don't need bees for pollination.

New estimates suggest that 95% of Earth's biomass (everything alive weighed out on a scale) is in bacteria. Fundamentally, life on Earth is bacterial, and everything else is an experimental add-on of dubious value. We humans each carry around 10 pounds of gut bacteria, without which we could only digest water, sugar, salts. Gut bacteria make two essential B vitamins for us and predigest EVERYTHING else. Simply put, us hominids are walking talking thinking symbiotic bacterial fermentation vats. Meanwhile, life in soil is so complex that my leading expert (Margulis) says that she doesn't even know how to classify it all. There are micro-lobsters living in some desert soil mats, found in places like southern Utah. There is a bacteria that thrives in the cooling water tanks of nuclear reactors that has a mechanism for rapid repair of broken DNA strands. There, a human has a definite fatal dose of ionizing radiation within 30 seconds.

The bif bacteria are so profoundly different that we are forced to classify them within their own kingdom of life, the 'Archybacteria.' The five kingdoms now hypothesized are Archybacteria, Eubacteria, Monera, Fungi, and Eukaryotes. Your family is the eukaryotes. There is a hypothesis for life's origin called 'Pansperma' or Panspermia' posing that bacteria inhabit worlds across the cosmos, that they travel around with the gases and debris of stellar explosions, and drop-in on new planets along with comets and other sorted far-traveled items. They're probably capable of this. Virus particles, at the very edge of life itself (they do not metabolize), are unknown players in all this - I am suspicious of their role as the true carriers of DNA coding procedures. This idea of life's origin not on Earth is now found in textbooks, sometimes alongside 'Divine Intervention' as another option for life's origin. I think it is quite logical to suppose that life of all kinds is found widespread in our greater world with its ethereal gods on-high. This is likely the next step-up in our education, ascertaining more of our place in a truly unbounded universe of infinite age and extent.

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