galaxies, unimagined in ancient times
Time is the motion of particles relative to each other. From a scientific perspective, without motion and without matter there is no time. If the material universe had a beginning, time as we know it began when the universe began. But science can postulate no such beginning.
None of us grasps reality in its entirety. With incomplete knowledge, physicists grasp the universe as energy (E), equal to mass (M) times the speed of light (C) squared (Emc2). Any mass, including rock, has energy, detectable when its atoms are split. And, astronomers gather that the universe is expanding, that galaxies have been moving away from a dense central configuration for the past 15 billion years since the so-called "big bang."
Scientists have mapped celestial bodies. Nearest to our galaxy – the Milky Way – is the Canis Major Dwarf Galaxy, 25,000 light-years from our solar system, a distance that would take 250,000 years to cover traveling at one-tenth the speed of light: 67,064,760 miles per hour). The farthest object from us that we know of is a distance of about 10 billion light years. In other words, the light from this object that we see today left there 10 billion years ago.
Getting more local, geologists claim that the sun and earth are around 4.55 billion years old, and they describe the sun as moving around our galaxy at roughly 500,000 miles per hour. One revolution around the galaxy is said to take 200 million years. Dividing 4,550 by 200 makes 23 revolutions around our galaxy since the sun and earth formed. This means that since the end of the last major ice age, some ten thousand years ago, the Earth has moved only one twenty-thousandth of a revolution through our galaxy.
Geologists describe the earth as having come together gravitationally. Hot and fluid energy was condensing into what we now see as the solids around us. The denser matter (iron and nickel) settled at the center. The less dense matter, in the form of rocks, rose to the surface. And, as the earth gave off heat, its outer layers cooled, leaving Earth's interior hot and molten. Gasses bubbled to the surface, eventually to become atmosphere. When the temperature was right, gasses in the atmosphere produced clouds that contained moisture – hydrogen and oxygen. It began to rain, and water began to cover much of the earth's surface.
Scientists consider that life might have come to the planet Earth with interplanetary dust or comets. Teams from the University of California, Berkeley, and from the University of Hawaii, Manoa, have shown that conditions in space are capable of creating complex dipeptides – linked pairs of amino acids – that are essential building blocks shared by all living things.
Biology, the study of life, includes botany, the study of plant life. Biologists claim that earliest forms of life consisted of carbon, water, nitrogen, oxygen, phosphor (sic), sulfur and other materials.
Among the chemicals on the Earth's surface are two nucleic acids: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). These acids can divide and replicate themselves.
About 3,800 million years ago there were on earth simple cells that lacked a nucleus: bacteria. About 3,000 million years ago photosynthesis developed. Photosynthesis occurred when sunlight acted upon a certain kind of bacteria and unicellular algae.
There was photosynthesis, a source of carbon within organic compounds, and these compounds released oxygen into the atmosphere. About 2,400 million years ago, photosynthesis began to oxygenate the earth's atmosphere.
About 2,000 million years ago organisms developed that were cells with complex structures enclosed within membranes – eukaryotes cells. Proteins within a cell, in a region called dehydrons, became unstable in a watery environment. With this instability, "sticky" proteins were more likely to work together in building more complex networks of gene and protein interactions. Around 1,000 million years ago multicellular life began.
Nearly all life was dependent on photosynthesis, which converted energy from the sun into food for an organism. Vegetable life in the form of algae transferred out of water and became more complex plant life, and plant life eventually became nutrition for creatures that crawled out of the ocean.
To survive, organisms were dependent upon on environmental conditions that includes moisture. This was so also for bacteria (hence preservation of food by freeze-drying). And like bacteria, virus microorganisms were also dependent on enviornmental conditions to survive. They were and are parasitical, reducing their power to expand indefinitely.
Around 600 million years ago organisms called simple animals appeared – organisms that included bacteria, which plants and animals needed for their survival. Bacteria worked in the digestive systems of insects and animals.
Simple animals acquired energy by devouring other organisms. To survive, both plants and animals needed the ability to pass moisturize through their systems – to absorb and to excrete water.
Some people see happenstance in these creations. The branches of trees reach out unevenly with leaves exposed to needed sunlight. A chaos of creeks meander from various directions to a lower elevation and forms a lake surrounded by a chaos of vegetation. The genetic mutations of organisms has also been viewed as a similar kind of chaos toward an end result: survivability.
Biologists today see genetic mutations in micro-organisms. Knowledge of this has progressed to the point where biologists can now alter or add a characteristic to an animal's DNA, fluorescence for example, that will be passed to their offspring.
Creatures with jointed bone structures, called arthropods, are estimated to have come into existence around 570 million years ago. And around 500 million years ago fish appeared, followed 25 million years later by land plants.
Scientists calculate that around 400 million years ago, sea temperatures fell to levels near today's temperatures, creating a more hospitable environment for species to flourish. In what is today Poland, the footprints of four-legged creatures – surmised to have been crocodile-like – have been found preserved in carbonate rock, the footprints are estimated to be 397 million years old. Another estimation is that 300 million years ago, spiders appeared that had the ability to make silk but not to make webs, before there were flying insects to catch.
Around 360 million years ago came amphibians. Sixty million years later reptiles appeared, and 100 millions years after that came the first mammals.
Plant life was able to survive without a brain. It received its nutrition and moisture without having to make choices. But creatures that needed to make an effort to get nutrition and to protect themselves would not have survived without a brain.
Around 230 to 220 million years ago dinosaurs first appeared. Paleontologists estimate that the age of the dinosaurs (the Jurassic Period) began 20 million years later. Approximately 80 million years later mammals first appeared – in the form of small nocturnal creatures that fed on insects and nursed their young. Paleontologists estimate that dinosaurs became extinct 65 million years ago, while birds and other smaller creatures better able to survive flourished. Scientists calculate that 38 million years ago primates appeared – creatures resembling monkeys and apes.
Biologists speak of variation between species and within species – a specie being creatures that can interbreed. Within a specie, imprecise replications occur from parent to offspring – unlike cloning, which creates identical genetic duplicates. Across a great span of time, some variations survived and other variations did not.
The fossilized bones of an ape that lived around 10 million years ago was discovered in a volcanic mud deposit in what is today northern Kenya. It is considered among those primates that preceded gorillas, chimps and humans. To quote the science reporter for the BBC, Helen Briggs, "Genetic studies suggest that the ancestors of humans and chimpanzees went along their separate pathways of evolution about five million to seven million years ago."
According to findings at an archaeological dig in what today is southeastern Spain, 1.8 million years ago the following creatures lived side by side: giant hyenas, saber-toothed cats, zebras, giraffes, gazelles, wolves, wild boar and lynx (BBC, October 30, 2007).
DNA analysis suggests that the common ancestor of modern humans, (homo sapiens) and Neanderthals lived between 800,000 and 520,000 years ago and that around 700,000 years ago a the began developing into distinctly different species.
Biologically, humans are a work in survival. The species of animal that we call human developed across thousands of years. Humans have many of the characteristics of other animals, including those that lived in trees. But an ancestor of the human species had become too big to live comfortably in trees. A human's legs had become longer and his pelvis reshaped, both of which helped the human to walk and run upright, which was more energy efficient and helped in running after game. Humanity's skin was exposed, keeping it cooler with sweat and evaporation and allowing it to run farther without suffering heat stroke as did their prey. Unlike chimpanzees, humans had broad shoulders that allowed it to throw stones and spears with deadly force. The human species benefited from brain development, allowing people to adapt to the ups and downs of climate change across the thousands of years in addition to various other circumstances.
Humans have a brain chemistry – dopamines to be exact – that make them want to eat and to have sex, without which the human species would not survive. Body chemistry also made fighting and empathy possible, the latter allowing them to live in a group.
Hunting and gathering required access to great stretches of land that was not occupied by other humans. Enough game was left to them by other predators. They could gather food that grew wild, and they had access to drinkable water.
Unlike chimpanzees, their genes structured their brain in a way that allowed complex verbalization. They had the ability to reflect on their activities and actions.
Humans need to have been born with the right body chemistry for their minds to contend with life. If they don't have it, they are dependent on others who do. With a settled and affluent existence, humans have been better able to care for these individuals.
Given the brain that they have inherited, humans have been better able than other species to manipulate their surroundings. Unlike other creatures they have altered landscapes and the atmosphere.
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