Nothing more and nothing less than 8,000 million humans currently live on the planet, barely 11 years after the already stratospheric figure of 7,000 million was reached. And the billionaire Jeff Bezos already predicted in 2018 that, sooner or later, we would reach a population of up to a trillion people… scattered throughout the solar system.

Assuming such a number of individuals on Earth is not easy. Resources must be optimized to avoid insurmountable inequalities and even more so in the face of growing climate change. Nothing like this had ever been experienced in all of history. One only has to think that, in the not too distant past, people rarely interbred with other humans.

Imagine if we compare ourselves with the Neanderthals, that extinct species that populated Europe, the Middle East and Central Asia between 230,000 and 28,000 years ago. That group of the genus Homo barely reached a maximum number of 10,000 individuals. “Today, there are about 800,000 Homo sapiens living in the same space that a Neanderthal occupied,” says Penny Spikins, a professor of archeology at York University.

“Also, humans live in social groups, but the closest Neanderthal tribes to each other were probably more than 100 kilometers apart. Finding a partner outside of his own family was a challenge,” Spikins explains in an article published on The Conversation.

When both cousin species collided for the dominance of hunting areas, it was Homo neanderthalensis that ended up giving in to the push of evolutionarily improved modern humans. But what would have happened otherwise? What would Earth be like if Neanderthals had prevailed?

Spikins is clear that Neanderthals tended to stay in their family groups, plus they were more wary of new people. “So their population density would probably be much lower than ours,” he says. It is hard, for example, to imagine them building cities, “since they were genetically predisposed to be less friendly.”

Sapiens are (a priori) different. We are more likely to interact with people outside of our own family, creating a more diverse genetic pool that over the centuries has helped reduce health problems, even as large populations make it easier for pandemics to spread.

“Neanderthals -says the York University archaeologist- could have lived shorter lives than modern humans, but their relative isolation would have protected them from infectious diseases that sometimes wiped out entire populations of modern humans.”

Homo sapiens may have a 10 to 20 percent faster rate of reproduction than previous species of humans. But having more babies only increases the population if there are enough resources to feed them. So our ancestors, says Spikins, had to create broader networks that not only allowed the circulation of food, but also weapons, jewelry or ideas.

“In an alternate world where Neanderthals would have thrived, it is unlikely, for example, that humans would have fostered relationships with animals through domestication,” the researcher writes. “Things might also have been different if changes in environments hadn’t generated so many sudden deficits, such as sharp declines in plants and animals,” she adds.

During the last ice age, around 20,000 years ago, temperatures across Europe were 8 to 10 degrees Celsius cooler than today, and the German records were more like those of present-day Siberia. Most of northern Europe, even, was covered in ice for six to nine months of the year.

During the last ice age, animals such as mammoths became extinct. There are more than a hundred representations of these prehistoric giants in Rouffignac (France) dating from the time of their demise, suggesting that the Sapiens mourned this loss.

“But it’s more likely that mammoths would have survived if it hadn’t been for the rise of Homo sapiens, because there would have been fewer Neanderthals to hunt them,” says Penny Spikins. “The more technology humanity develops, the more the use we make of it damages the planet. Intensive farming is draining our soils of nutrients, overfishing is wrecking the seas, and greenhouse gases are causing extreme weather. Overexploitation was not inevitable, but our species was the first to do so. There is no such thing as Planet B. But if Neanderthals had survived instead of us, we would never have needed one,” she warns.