The earliest life forms we know of were microscopic organisms (microbes) that left signals of their presence in rocks about 3.7
The same goes for deep-sea hydrothermal vents. These chimney-like vents form where seawater comes into contact with magma on the ocean floor, resulting in streams of superheated plumes. The microorganisms that live near such plumes have led some scientists to suggest them as the birthplaces of Earth's first life forms.
The variety of life on Earth is widely considered to have evolved from a single common ancestor, but it is possible that basic organisms emerged more than once, leading to multiple trees of life.
The land was barren, likely dry and rocky. Locally, there may have been microbial soil crust. There was no vegetation as we know it today - no grass, no trees, no plants. This photo shows what the land may have looked like 500 million years ago, during the Cambrian Period.
Divine creation, evolution, spontaneous generation, and cosmogenesis are the four theories examined.
IN 4.5 billion years of Earthly history, life as we know it arose just once. Every living thing on our planet shares the same chemistry, and can be traced back to “LUCA”, the last universal common ancestor.
The most accepted theory for the origin of life is Oparin - the Haldane theory. Reason for acceptance of this theory: This theory states that from the abiogenetic material organic molecules could be formed in the presence of an external energy source.
After the dinosaurs died out, nearly 65 million years passed before people appeared on Earth.
The age immediately prior to the dinosaurs was called the Permian. Although there were amphibious reptiles, early versions of the dinosaurs, the dominant life form was the trilobite, visually somewhere between a wood louse and an armadillo. In their heyday there were 15,000 kinds of trilobite.
With this context and timeframe in mind, the demographers estimate that 109 billion people have lived and died over the course of 192,000 years. If we add the number of people alive today, we get 117 billion humans that have ever lived.
The earliest life forms we know of were microscopic organisms (microbes) that left signals of their presence in rocks about 3.7 billion years old. The signals consisted of a type of carbon molecule that is produced by living things.
Humans and monkeys are both primates. But humans are not descended from monkeys or any other primate living today. We do share a common ape ancestor with chimpanzees. It lived between 8 and 6 million years ago.
The first organisms may have evolved before the rocky planets formed. Life may have arisen in our solar system before Earth even finished forming.
Adam is the name given in Genesis 1-5 to the first human.
The likely "first human", she says, was Homo erectus. These short, stocky humans were a real stayer in human evolutionary history. Estimates vary, but they're thought to have lived from around 2 million to 100,000 years ago, and were the first humans to walk out of Africa and push into Europe and Asia.
Anatomically modern humans emerged around 300,000 years ago in Africa, evolving from Homo heidelbergensis or a similar species and migrating out of Africa, gradually replacing or interbreeding with local populations of archaic humans.
For approximately 120 million years—from the Carboniferous to the middle Triassic periods—terrestrial life was dominated by the pelycosaurs, archosaurs, and therapsids (the so-called "mammal-like reptiles") that preceded the dinosaurs.
It's impossible. The DNA has changed so much, even just in the 68 million years, since teeth were lost in the, you know, living bird lineage of dinosaurs, cause teeth were actually lost in dinosaurs, like at least a dozen times. And the beak was evolved, you know, teeth lost really beak evolved many times.
After the dinosaurs' extinction, flowering plants dominated Earth, continuing a process that had started in the Cretaceous, and continue to do so today. But all land animals weighing over 25 kilogrammes died out. 'What we're left with are basically the seeds of what we have today.
According to the Bible, dinosaurs must have been created by God on the sixth day of creation. Genesis 1:24 says, “And God said, Let the earth bring forth the living creature after his kind, cattle, and creeping thing, and beast of the earth after his kind: and it was so.”
They would still probably be small, scrawny, and very generalized. But instead, the mammals were able to evolve and diversify and, well, ultimately, millions of years later, become some humans. So perhaps we would not have been here if it weren't for this extinction event 65 million years ago.
In fact, birds are commonly thought to be the only animals around today that are direct descendants of dinosaurs. So next time you visit a farm, take a moment to think about it. All those squawking chickens are actually the closest living relatives of the most incredible predator the world has ever known!
As the Earth started to grow, about 4.56 billion years ago, the heavy iron sank to the center, and the lighter silicates rose to the surface. Heat generated from impacts of other bodies kept the early Earth molten. In fact, the planet's entire outer layer may have been liquid, an idea that came from studying the Moon.
At present, perhaps the oldest acknowledged evidence of life on the planet is found in 3.48-billion-year-old rocks in Western Australia. This material is said to show remnants of stromatolites - mounds of sediment formed of mineral grains glued together by ancient bacteria.
One of the leading theories is that life emerged from chemical processes in Earth's early ocean. Simple chemical precursors, such as water, carbon, and hydrogen, mixed and mingled until they formed complex polymers like DNA, RNA, and protein—the building blocks of life.