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-------------------------- 2442 - MICROBES - the simplest life on Earth?
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- Octopus genes are more advanced than any other order of animals on Earth. One of the groups of genes that they exhibit codes for the development of their amazing distributed nervous system. On top of this, octopods possess regenerative and camouflage capabilities, and are among the smartest animals on the planet.
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- There are species of single celled organisms called Archaea that survive in environments so harsh they would melt the flesh from your bones in seconds. They live in super alkaline lakes, in the ultra-high pressure, alongside high temperature hydro-thermal vents, and can even survive high doses of gamma radiation. These are not bacteria, and may indeed be the earliest form of prokaryotic life on Earth.
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- Tardigrades, known as water bears, can survive in the harsh cold and pure vacuum of space, and can put themselves in a dormant state in which their metabolism reduces to 0.01% of normal, allowing them to live to nearly 30 years in more moderate conditions, essentially extending their expected lifespan of only a few months by 300 times.
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- There are four species of Hyena, that powerful and hardy scavenger that lurks in the African Savannah. Though they have physical and behavioral characteristics of both cats and dogs, they are neither. Hyenas belong to their own family, Hyenadae, and they evolved and thrived because they fit a particular niche in their ecosystem.
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- Marsupials were once the dominant mammalian order on the planet. Like other mammals, they give birth, but the young are undeveloped and spend most of their time outside of the mother’s body suckling and growing in a pouch. Marsupials boasted gigantic grazing species and terrifying predators the size of lions, but were eventually out competed by other mammals in those particular niches and now only exist in Australia and the Americas in more limited capacities.
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- There is a species of jellyfish that, when reaching a point of being too old, injured or sick, reverts back into its “childlike” polyp state and then re-grows, creating a cycle of near immortality.
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- These are a few creatures that live with us now, and they are nearly as different from us as much alien life will be. But, despite how different these subjects are, the fact remains they evolved on Earth, with us. We are all descendants of the very first living cells that appeared sometime between 3.8 and 4.3 billion years ago.
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- Since then, life has been branching out in innumerable different directions, constantly testing the boundaries of its environments to see what forms can thrive and what forms are insufficient. Survival of the fittest has been at play for billions of years.
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- Scientists estimate that there may be as many as 8.7 million species currently alive on Earth today. We’re only sure of roughly 1.2 million of those, which are catalogued. It’s taken the work of many generations of explorers and biologists to find and record them.
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- They discover, on average, about 50 new species every day, based on the 18,000 found in 2016. At the same time 150 species go extinct every day in our modern world, which may be 1,000 times the natural rate. This means that we are losing species 3 times faster than we are finding them.
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- By this time next year, 36,000 types of living things will have gone extinct before we get a chance to witness their existence.
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- What about all those species that lived, but we’ll never discover? Based on the data scientists have currently, most species tend to exist for a period of 3 million years, at most, before they disappear, meaning went extinct.
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- The fossil record as we know it comes almost entirely from evidence found in sedimentary rock, which generally is only found very near the surface of the planet. Over the huge expanse of geologic time, billions of years, via plate tectonics, volcanism and asteroid impacts, most of those deposits that have ever existed have been subsumed into much deeper layers of the planet.
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- When you consider the countless potential species of microscopic organisms, which multiply so quickly and have such short generations, there have likely existed many billions of species on Earth since the dawn of life.
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- All of life as we currently know it, everything we see living around us today, represents at most half a billion years of evolution. Every recognizable form of life, from flowers to insects to dinosaurs to deer, evolved in less than 1/8th of the time life has been on Earth.
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- So much time is unaccounted for, so much evolution, that there may have been enough time for multiple entire other complete evolutionary trees to develop before being totally wiped clean from the face of the planet.
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- Earth is not our Earth. It’s belonged to living things for so long that there may have been advanced, even intelligent, species to come along billions of years ago. It’s just been so long, with so many geologic changes along the way, that any evidence of their time here could never be uncovered.
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- Neanderthals only existed for a few hundred thousand years before being put out of business by modern humans, Homo sapiens. All of the genus Homo has only been around for roughly 2.5 million years.
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- Apes have only existed for 15 million years, while modern sharks have managed to thrive for more than ten times that amount of time.
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- Will modern humans manage to survive for millennia more, then we may have a chance to “disappear” like so many other species have: Our species slowly transforming over time into new species, perhaps because we transport populations off-planet.
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- Homo sapiens is the latest branch in a singular limb of the evolutionary tree. We have caused the extinction of many other of our fellow species, and continue to do so, at an alarming rate. At the same time we are discovering other species that survive far beyond our expectations.
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- Stirring in the depths of Canada's Kidd Mine. The zinc and copper mine, 350 miles northwest of Toronto, is the deepest spot ever explored on land and the reservoir of the oldest known water. And yet 7,900 feet below the surface, in perpetual darkness and in waters that have remained undisturbed for up to two billion years, the mine is teeming with life.
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- Many scientists had doubted that anything could live under such extreme conditions. However the mine’s dark, deep water harbors a population of remarkable living microbes.
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- The single-celled organisms don’t need oxygen because they breathe sulfur compounds. Nor do they need sunlight. Instead, they live off chemicals in the surrounding rock, the glittery mineral pyrite.
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- Scientists are starting to find similar microbes in other deep spots, including boreholes, volcanic vents on the bottom of the ocean and buried sediments far beneath the seafloor.
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- Cut off from light, air, and any connection to the surface, this shadowy realm seems more like an alien world than part of Earth. Exploring it could help us understand how life might have begun on other planets as well as on our own. We might even find alien-like creatures living undetected right beneath our feet.
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- Geobiologist estimate that some 5 x 10^29 cells live in the Earth. Collectively, they weigh 300 times as much as all living people combined.
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- The denizens of the deep are an exotic bunch even beyond their appetite for solid rock. One species can live at temperatures of 250 degrees Fahrenheit, well above the boiling point of water and close to the theoretical limit at which vital organic molecules start to disintegrate.
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- Separate studies of material drilled near the Mariana Trench in the Pacific Ocean hint that some organisms could be living six miles below the seafloor, limited only by the heat at such tremendous depths.
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- Laboratory experiments show that some microbes can tolerate pressures 20,000 times higher than the air pressure at sea level, meaning that there are almost certainly more extreme ecosystems out.
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- We do not really understand the limits of life. The pace of existence in the deep also seems radically different from that on the surface. Where food and energy are scarce, to compensate, cellular metabolism slows almost to a standstill.
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- Many of the microbes may survive for thousands of years or more without dividing, just replacing their broken parts. There are so many deep microbes that, despite a seemingly lazy existence, they collectively exert a huge impact on their habitats.
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- For example, a community of cells on the ocean floor consume methane gas that bubbles up from ancient sediment. Deep subsurface microbes eat massive amounts of methane that would otherwise be released helping curb atmospheric levels of a potent greenhouse gas.
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- Fossils show that surface life has changed enormously over billions of years, but slow-motion deep life may retain much of its primitive characteristics.
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- Scientists want to sequence the genes of the Kidd Creek microbes and then do a 23andMe analysis to unravel their kinship to other residents of the deep Earth. We want to learn if they are all still close relatives, or have they diversified and adapted significantly to their local environments?
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- Sulfur-breathing microbes living beneath thick, protective layers of rock would have been well suited to the brutal conditions on our planet when it was young.
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- Another possibility is that life originated more than once, with other forms still surviving somewhere on Earth. And, maybe somewhere on another planet or another moon. The more we learn the more complex it gets. Keep learning.
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- September 12, 2019
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