In the mid-21st century, after several industrial and technological revolutions, it is clear that the human species can drastically modify the landscape of the planet. However, satellite data shows that even small groups of hunter-gatherers can change the environment of a place significantly.

Although we can't see the Great Wall of China from space, scientists can extract a lot of detail from a satellite image. Much of this data even indicates human activity and its effects on a landscape.

Now researchers have combined this type of research with archaeology, and shown that even small populations of early humans were already causing significant changes in the environment.

Using satellite images of the island of Madagascar, scientists have analyzed the relief and soil of several parts of the southwest of the island. The detail is that some of these regions were known to have been inhabited by primitive communities of fishermen and hunter-gatherers. This is because several artifacts came from these regions.

Vegetation in Madagascar. Image: Jean-Philippe Déranlot / Pixabay

However, the survey showed significant variation in the terrain of the regions inhabited by the Homo sapiens Over almost 500 square kilometers, at least 17% of the territories have suffered in the long term by human action.

That is, even without agriculture or machinery, humans were already capable of changing the environment in quite profound ways.

Why would a hunter-gatherer change the environment?

In addition to data from the PlanetScope satellite, the research published in the journal Frontiers in Ecology and Evolution also used algorithms of forest and vegetation change on the island. All this, therefore, to predict the coevolution of vegetation and humans in Madagascar.

"What we find is that the areas surrounding these [human occupation] sites, which appear to be pristine, are not. We see a slight change in the ability of the soil to retain water. This is indicated by a shift in spectral reflectivity seen in the satellite images." So says author Dylan S. Davis, to Penn State News.

It turns out that this characteristic of changing the environment happens even with the slightest presence of human beings. This is because the shape and composition of the environment depend directly on the species that live in it. And let's face it, we humans make several modifications in nature.

However, there is still no concrete evidence that the change in soil cited by Davis was actually caused by humans inhabiting the regions. Still, the hypothesis is strong.

Image: Hans Braxmeier / Pixabay

Most research of its kind, by the way, shows the impact of farming communities on the resources and conditions of the environment. However, the research points out that this kind of change was probably happening thousands of years before we created our model of agriculture.

"We underestimate the impact that non-agricultural societies have in shaping landscapes. These are subtle, but they can be discovered," says coauthor Kristina Douglass. "Looking at the landscape around the world, we find that people have modified more of the world than we previously thought."

The research is available in the journal Frontiers in Ecology and Evolution.