When I think about alien groups, my mind links stars and planets with time. I see far stars and hidden planets. I add time into this mix. I ask: Did alien people live on Earth long ago? They may have grown, thrived, and then faded. I wonder if their traces lie deep beneath us. I review views from science and reflect on what this means for us.

Life on Earth: A Vast Timeline for Possible Civilizations

Earth is very old. It holds four billion years of life. For most of that span, single cells ruled. Then, about 540 million years ago, many animals appeared. This long stretch gives space for alien people to have come before humans.

Modern humans have existed for about 300,000 years. Early on, our small groups gathered food and moved with the land. Life was slow and simple. About 10,000 years ago, farming changed our way of life. People began to grow food, build groups of many, and form cities with great structures like temples and pyramids.

Some 300 years ago, an industrial change began. This shift sped up growth and left clear marks on the planet. In human history, hunters are 97%, farmers 2.9%, and industrial folk just 0.1%. In Earth’s long span, we are very new.

The Fleeting Nature of Civilization’s Physical Traces

Long periods make it hard for things to survive. The oldest large rocks, such as in the Negev, date to 1.8 million years. Much older things break, sink, or hide under ice and seas. Even our own time may leave just a thin layer in the future. In millions of years, only a tiny mark might remain.

If alien people passed through life stages like hunting, farming, and industry, one asks: What remains would tell their tale?

Hunter-Gatherer Aliens: Lost Without a Trace?

On Earth, groups like Homo erectus, Neanderthals, and Denisovans lived for many years. They made tools, used fire, and even produced art. They left only weak marks in rocks. Fossilizing is not an easy task. Many early smart ones might have left almost no sign.

If other smart beings lived as hunters, their tools and art would fade. Their remains might be few and hard to tell apart from the stones.

Agricultural and Empire Aliens: More Lasting Legacies

Farming people made visible marks. They built cities and monuments, wrote words, and made buildings. In our history, empires came and went. Their stone works, like Egypt’s pyramids, still stand.

If alien empires had grown in recent millions of years, we would likely see some marks. So far, scientists have not found these signs. This gap does not cancel the deep past. Many millions of years back, before lots of animals came along, alien groups might have risen.

Then, even smart people with pre-industrial ways would have left little trace. Wood, stone marks, and changed lands might now look like nature. Other life forms, perhaps with senses unlike ours, may have built great cities that now have vanished.

Industrial Civilizations: What Will Remain?

What if industrial alien people once lived on Earth? Their work makes clear marks. They can leave traces like odd isotopes or man-made chemicals.

Today, we change Earth greatly. We drive species to end, spread plastic waste, change the soil, scar the land by mining, and add carbon to the air. These acts may mark Earth for millions of years.

Yet, scientists have not seen signs of past industrial groups. No strange chemical layers or isotopes stand out from normal or human-made causes. This silence may mean any past industrial group did not last long or left very soft marks.

The Temporal Fermi Paradox and Our Place in Time

This view brings a twist to the Fermi puzzle. Space does not show many alien signs, and time does not either. Current science tells us Earth did not host another group at our level, at least as shown in the rocks.

One thought comes clear: our future is not set. Past industrial groups may have fallen from our own mistakes or nature’s force. We might live in a short chance to keep life and build on it.

Conclusion: The Search Continues Across Time and Space

The idea of old alien people on Earth stays a puzzle, one that still grabs our thought. The long span of time, like the vast space above, looks empty of other smart groups on land. New finds in soil, rocks, and the sky may yet change our view.

Until that day, it is our task to guard our own time. Perhaps in millions of years, another group—or even our kin—may read our marks in the stones if they still lie there.

We set our path by looking out at stars and back into deep time. We ask who we are, where we come from, and if we stand alone.