Billions of Years -- a scientific theory

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, including scientists, grasps reality whole. With incomplete knowledge, physicists grasp the universe as energy (E), equal to mass (M) times the speed of light (C) squared (Emc2). Any old mass, including rock, has energy, detectable when its molecules are split. And astronomers gather that the universe is expanding, that galaxies have been moving away from a dense configuration for the past 15 billion years.

Scientists have mapped celestial bodies as best they can. The nearest galaxy to our galaxy, the Milky Way, would take 2 million years to span at the speed of light (299,793 kilometers or 186,291 miles per second). The farthest known object in the universe known to us is believed to be at a distance that takes light to travel in about 10 billion light years. In other words, what we see today of this object is that object 10 billion years ago. And for the map of celestial bodies to make sense, the universe has to be more than 10 billion years old.

Geologists claim the sun and earth to be 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. Ten thousand years covers only one twenty-thousandth of a revolution.

Geologists describe the earth as having come together gravitationally. Hot and fluid energy was condensing into what we know as solids. 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 first, 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.

Among the chemicals on the Earth's surface were two nucleic acids: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). These acids could divide and replicate themselves. Biologists claim that earliest forms of life consisted of carbon, water, nitrogen, oxygen, phosphor (sic), sulfur and other materials. Although they were not discovered until the 19th century, micro-organisms existed, presumably, and these organisms could mutate genetically. Knowledge of this is established to the extent that biologists can alter a characteristic in mice, for example, that will be passed to their offspring.

Biologists have found frequent genetic mutations in micro-organisms. They have theorized about millions of years of genetic evolutions, of plant-life and spineless creatures that developed in ocean water. The theory is that change has occurred in species as some mutations have not served survival while some mutants -- perhaps a tiny percentage -- have survived and multiplied.

Vegetable life in the form of algae transferred out of water and became more complex -- and plant life became nutrition for creatures that crawled out of the ocean.

Plant life absorbed nutrition without effort and therefore did not need to make decisions of the sort made some other forms of life. Plant life was able to survive without that decision making instrument: a brain. Creatures that needed to make an effort to get nutrition and to protect themselves would not have survived without a brain to give them the ability to decide when and where to move. And so they had brains.

Scientists calculate that more than 3.5 billion years after the earth had formed, that more than 400 million years ago sea temperatures fell to levels near today's temperatures, creating a hospitable environment for species. 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 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 spider webs. No matter: there were not yet flying insects to catch. Around 230 to 220 million years ago dinosaurs first appeared. They estimate that the age of the dinosaurs (the Jurassic Period) began 20 million years later. Around perhaps it was 80 million years later that mammals first appeared -- in the form of small nocturnal creatures that fed on insects and nursed their young. Paleontologists describe dinosaurs as having become extinct 65 million years ago, with birds and other smaller creatures better able to survive. Scientists calculate that 38 million years ago primates appeared -- creatures resembling those we call 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. Across a great span of time, some variations survived and other variations did not.

The fossil of an ape that lived around 10 million years ago has been 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 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 human-kind and Neanderthal-kind began diverging. Humans (homo sapiens) are said to have lived about 60 thousand years ago in Africa. A poetic description has humans as below the angels, and indeed humans have survival techniques similar to other earthbound creatures that move around to get nourishment, including the unangelic ability to excrete what they ingest but cannot use.

Biologically humans are a work in survival. The human species didn't fall out of the trees in a sudden change from a chimp-like creature. The human species developed across thousands of years. They had some characteristics of species that did live in trees, but their ancestor-species had become too big to live comfortably in trees. Their legs had become longer, which helped them in running across ground after game. They walked and ran upright which was more energy efficient. Their skin was exposed, keeping them cooler with sweat and evaporation and allowing them to run farther without suffering heat stroke as did their prey. Unlike chimpanzees, they had broad shoulders that allowed them to throw stones and spears with deadly force. They benefited from a growth in brain size, needed in adapting to the ups and downs of vast climate changes across the thousands of years. And unlike chimpanzees their genes structured their brain in a way that allowed complex verbalization.

Humans have a chemistry that made fighting and empathy possible, the latter allowing them to live in a group, which added to their ability to survive. Like other living things that move around to get nourishment, they had the ability to make choices. And they had the ability to reflect.

That which humans called angels were unchallenged physically. All organisms were. Every virus and larger organisms, such as scabies, needed moisture and a host to survive. If they had been able to thrive with less challenge, the human species would have lost its struggle with the microscopic world. Humans also had external environmental challenges, and they needed the right bodily chemistry for sanity and for the awareness that guided them in contending with their surroundings. And humans were better able than other species to manipulate their surroundings.

to "Dinosaurs, Birds and Survival"

Public Broadcasting (PBS)

NOVA, Becoming Human

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