When did life on Earth begin?

Answer 1

Earth formed about 4.5 billion years ago. No one knows exactly when or how life began, and the final, most important events leading to the origin of life are perhaps the least understood chapters of the story. Most of life's history involved the biochemical evolution of single-celled microorganisms. We find individual fossilized microbes in rocks 3.5 billion years old, yet we can conclusively identify multicelled fossils only in rocks younger than 1 billion years.

The oldest microbial communities often constructed layered mound-shaped deposits called stromatolites, whose structures suggest that those organisms sought light and were therefore photosynthetic. These early stromatolites grew along ancient seacoasts and endured harsh sunlight as well as episodic wetting and drying by tides. Thus it appears that, even as early as 3.5 billion years ago, microorganisms had become remarkably durable and sophisticated.

Answer 2

I'm not sure but plant were the first living things on our planet,starting with very simple plants such as algae.Then mosses and liverworts developed,followed by ferns and other larger plants.Animals did not leave the sea until plants had been fully established,otherwise there would have been no food for them

Next were relatives of spiders and scorpions which were probably the first creatures to leave the sea and actually colonized on land.Later they evolved into larger and more complex forms of life.Amphibians multiplied rapidly,and the word actually means 'living on land and in water'

Answer 3

Earth is about 4 Billion years old and the Galaxy is 16 Billion years old. I would say life on Earth probably started 3 Billion years old.

Answer 4

Most of life's history involved the biochemical evolution of single-celled microorganisms. We find individual fossilized microbes in rocks 3.5 billion years old, yet we can conclusively identify multicelled fossils only in rocks younger than 1 billion years.

The oldest microbial communities often constructed layered mound-shaped deposits called stromatolites, whose structures suggest that those organisms sought light and were therefore photosynthetic. These early stromatolites grew along ancient seacoasts and endured harsh sunlight as well as episodic wetting and drying by tides. Thus it appears that, even as early as 3.5 billion years ago, microorganisms had become remarkably durable and sophisticated.

Many important events mark the interval between 1 billion and 3 billion years ago. Smaller strips of land dominated by volcanoes were joined by larger, more stable continents. Life learned how to extract oxygen from water, and living things populated the newly expanded continental shelf regions.

Finally, between 1 billion and 2 billion years ago, eukaryotic cells (those with a nucleus) developed, with complex systems of organelles and membranes. These organisms then began to experiment with multicelled body structures.

The evolution of the plants and animals most familiar to us occurred only in the last 550 million years. Marine invertebrates (such as shell-making ammonites) appeared first, then fish, amphibians, reptiles, birds, mammals and humanity. Land plant communities also evolved from relatively ancient clubmosses, horsetails and ferns, to the more recent gymnosperms (for example, conifers) and angiosperms (flowering plants).

Answer 5

hahaha this was a biology class question some time ago for me, but it I think the first live organism (cell) started 1.2 billion years after the Earth was created. I think it was 3.2 billion or something. I forget.

Answer 6

In the Archaean Eon about 4 billion years ago - evidence found in stromatolites in rocks in the Pilbara in Australia

Answer 7

Noone knows for sure when life began, since there was noone there to observe it.
Any ansawer is therefore a philosophical one not a strictly scientific one.

The idea that life has been around for millions/billions of years was 'invented' to support the philosophical idea of evolution.

In fact the evidence does not support this view.
Abiogenesis (life arising from non-life) was disproved by Pasteur years ago, and has no scientific merit whatsoever.
http://www.googlesyndicatedsearch.com/u/creationontheweb?q=abiogenesis&hl=en&lr=

There is much evidence that the earth and universe are not millions/billions of years old.
E.g. decay of earth's magnetic field
the existence of short-lived comets
recession of the moon
the salinity of the sea
etc,etc.
http://www.creationontheweb.com/content/view/3040/

I prefer to accept the eye witness account of the only one who was there - the Creator.
Life began around 6000 years ago.

Answer 8

My son will tell you life on earth began when he hit 18.

Answer 9

Nobody knows for sure!! From either the Biblical of Evolutionary position. I would guess life began when somebody realized they were alive. Good question skycat!

Answer 10

4 billion years but human beings have been on earth foe 1 million years