The imprint of humanity is visible all over the planet today, from the towering skyscrapers that define our modern metropolises to the pyramids and other ancient monuments of our past. But what would our planet be like if modern man had never appeared?
Some scientists say it would be a place with wildlife and a wide variety of animals, according to Live Science.
A world without modern man could also mean that our relatives, like Neanderthals for example, would still exist and bring about change in the world. Humans have shaped the world by wiping out many species through activities such as hunting.
The rate of extinction of some animals on Earth today is more than 100 times higher than it would be if there were no humans, according to estimates.
The man-made destruction of nature shows that the Earth would host more wildlife along with some lost “giants”, such as the Moa birds. These ostrich-like birds can reach a height of 3.6 meters. They evolved in New Zealand millions of years ago and disappeared within 200 years of the arrival of humans in their area 750 years ago. At least 25 other vertebrate species, including the giant Haast eagle (Hieraaetus moorei) that chased the moa, have also become extinct.
Giant moose and Haast eagles are recent examples of large animals whose extinction is closely linked to human activities, such as unsustainable hunting and the introduction of invasive species into new habitats. They are also indicators of how our relationship with large animals might have been. The survival of large animals is vital to speculation about an Earth without humans, as these beasts have such an impact on landscapes.
Soren Forby, a senior lecturer in zoology at the University of Gothenburg in Sweden, believes that humans played a key role in the extinction of many large mammals dating back thousands of years. He led a 2015 study published in the journal Diversity and Distributions, which suggested that without humans, the Earth would look very much like today’s Serengeti, an African ecosystem full of life.
Under this scenario, extinct animals similar to those living in the Serengeti today, including elephants, rhinos and lions, would live all over Europe.
A 2021 study published in the journal Nature concluded that climate change eventually wiped out hairy mammoths (Mammuthus primigenius) and other arctic beasts that survived the end of the Pleistocene.
People, however, were chasing mammoths. Scientists who believe that humans were probably the main factor in their extinction, claim that mammoths
survived climate change before the advent of man and could probably have survived to this day if it were not for the additional pressure exerted on them by man.
Christopher Dauti, an associate professor and ecosystem ecologist at the University of Northern Arizona, is modeling how large animals, past and present, move seeds and nutrients through diet and defecation. His work suggests that the transport of elements such as phosphorus, calcium and magnesium, which are vital to life, has been reduced by more than 90% due to the extinction of large animals.
Dauti assumes that without humans, the elements would be more evenly distributed on Earth. This would mean more fertile soil, which would make ecosystems more productive.
“If the data is heterogeneous in ecosystems, productivity will also be heterogeneous,” he said.
People tend to accumulate data with each other through practices such as farming and creating fenced areas, so these areas become less fertile over time compared to wild systems, according to Dauti. Higher fertility means that plants can allocate their pores to more fruits and flowers, so the world could be more alive and feed more animals.
Climate could also be different, and while it is difficult to say how humans and wildlife may have influenced climate change thousands of years ago, it is much easier to judge our influence on Earth today. Through global warming, caused by activities such as burning fossil fuels, man has raised the average global temperature by about 1 degree Celsius since the early 20th century. The Earth, therefore, would at least be cooler without us.
A 2016 study published in Nature concluded that man-made rising temperatures would delay an impending ice age by at least 100,000 years. However, this was not to happen for another 50,000 years.
The existence of people is inevitable
Scientists are not sure why Neanderthals became extinct about 40,000 years ago, but because they mingled with Homo Sapiens, parts of their DNA live on some of us. There may have been multiple reasons for the Neanderthal extinction, but we are the main suspect.
Chris Stringer, a professor and head of research on human origins at the Natural History Museum in London, believes the competition for resources was a factor in the Neanderthals’ disappearance. “If it weren’t for us, if we hadn’t come to Europe 45,000 or 50,000 years ago, I think they would probably still be here,” he told Live Science.
According to Stringer, Neanderthals lived a complex life in Europe, similar to that of modern humans, but found it difficult to cope with climate change, they were relatively few and with low genetic diversity.
Scientists are still learning new facts about at least one other human lineage that lived around the same time as modern humans and Neanderthals: the Denisovans. This lineage seems to be closer to Neanderthals than to modern humans in terms of genes and appearance, but it is distinct from Neanderthals because of its very large molars.
Humans probably crossed paths with the Denisovans, as there are traces of their DNA in modern humans living in places like New Guinea – a finding that shows the Denisovans were in Southeast Asia and interacted with the ancestors of modern humans who later settled according to with a 2012 study published in the journal Science. The Denisovans also mingled with the Neanderthals in Siberia, where the fossilized remains of a Denisovan-Neanderthal hybrid were found, according to Live Science.
These Denisovans’ interactions, together with fossil data, suggest that they were wider than the Neanderthals, which included a wider variety of environments, and therefore adapted better than the Neanderthals. DNA evidence also suggests that the Denisovans probably had more genetic diversity than the Neanderthals, according to Stringer.
According to the researcher, if one or both of these genealogical lines survived, they could follow a similar path to that of Homo Sapiens and reach the development of agriculture.