UCSB Science Line
Sponge Spicules Nerve Cells Galaxy Abalone Shell Nickel Succinate X-ray Lens Lupine
UCSB Science Line
Home
How it Works
Ask a Question
Search Topics
Webcasts
Our Scientists
Science Links
Contact Information
How did humans get to earth or how were they created?
Question Date: 2017-09-26
Answer 1:

This is a tough question to answer! Humans became humans through the slow process of evolution.

The process of evolution involves a series of natural changes (or mutations) that cause organisms to arise, adapt to an environment, and become extinct.

All organisms developed through evolution. Modern humans, Homo sapiens, likely first evolved in Africa over 300,000 years ago. But paleontology has found abundant fossil evidence that other hominins existed for millions of years for us, and that modern humans overlapped with another similar species, Homo neanderthalensis, or Neanderthals, and other ape-like primates. That, briefly, covers recent history on how humans came to be.

The history explaining how life even began on Earth, starts a long time further back. The earliest undisputed evidence for life on Earth is found in rocks from Greenland dated to 3.7 billion years. Though front-line evidence is under debate for earlier evidence found in 3.95 billion year old rocks from Labrador, Canada. Organisms as you think of them today have evolved from the most basic of microbes. This is called abiogenesis , or the natural process by which life arises from non-living matter. Creation of life is dependent on the special chemical properties of carbon and water, but there is no single theory for how life originated.

The most basic process requires the evolution of molecules into cells, which first required the formation of two specialized molecular chemicals: monomers (molecules that bind) and polymers (large molecules made up of numerous repeated subunits). Once cells evolved, they eventually organized into a molecular system based on biological order.

There is quite a bit more how those structures actually evolved into humans, but that is an advanced question that would require a much longer answer! I encourage you to keep exploring the origins of life.


Answer 2:

This is a very complex problem and we don’t really have a clear answer to it. We may never know the answer. Though it’s likely that humans didn’t arrive on Earth. There are hypotheses that an asteroid could have hit the earth and seeded it with life which eventually evolved into humans. Though this really just “kicks the can down the road” and doesn’t address how life began.

Generally scientists think that life began spontaneously out of non-living molecules and after a long time evolved into humans. That process would be mind boggling, but 4 billion years is also a very long time which means maybe it could happen. The scientific assumption is that this process was unguided and happened simply because the correct conditions occurred for it to happen. Over much of human history, philosophy and religion have dealt with the process of humans being created in various ways. In many of these interpretations, the creation of life was guided by a higher being. Science hasn’t found clear evidence that life was created deliberately so it doesn’t make this assumption.


Answer 3:

Humans evolved from an ape-like ancestor over time. There is presently no evidence that this ape-like ancestor was changed by any intelligent force, but it's difficult to prove that it didn't happen either. We can say that humans are related to other life on Earth thanks to the genes, chemicals, body parts, and other things that we share with other life-forms.

Because life-forms related to humans have lived on Earth for billions of years, we can be certain that humans did not arrive from space, for example, but it is still possible (just unlikely, given the lack of evidence) that our ancestors were modified from existing animals and did not arise purely through natural processes.


Answer 4:

Thanks for your question, it’s one of the most important questions science has addressed.

This question about the origin of life, and humanity’s place in it, motivated Charles Darwin. After a trip sailing around the world and making numerous insightful observations, Darwin theorized that all life evolves by natural selection.

Darwin’s idea combines a few claims about the world:
(1) all organisms are in competition over limited resources, especially opportunities to reproduce;
(2) organisms exhibit individual differences, few are totally alike;
(3) differences can be passed down in genes, for instance children resemble their parents;
(4) some individuals had traits that enhanced their ability to reproduce, better eyesight for example;
(5) those traits that enhanced an organism’s ability to reproduce then get passed down to offspring more often, and eventually that trait will become standard among the species –evolution has then occurred.

Darwin was also clear that humans are a product of evolution by natural selection – in our physical and mental traits. So humans appeared on the earth in the same way that all other living things did, as the product of the gradual accumulation of traits that lead to the survival and reproduction of our genes.

Thanks for the great question,


Click Here to return to the search form.

University of California, Santa Barbara Materials Research Laboratory National Science Foundation
This program is co-sponsored by the National Science Foundation and UCSB School-University Partnerships
Copyright © 2017 The Regents of the University of California,
All Rights Reserved.
UCSB Terms of Use