«We humans can easily disappear and be replaced by other forms of life»

In it he recreates in detail 16 historical periods now extinct, from the Pleistocene, 20,000 years ago, to the distant Ediacaran, 550 million years ago, and brings back to life ancient creatures as amazing as the familiar dinosaurs and woolly mammoths, or the lesser known giant penguins, three-meter-high mushrooms, glass reefs or feathered reptiles. All of them framed in environments with moving continents, extreme temperatures, meteorite impacts, global glaciations, superstorms and volcanic eruptions on a continental scale. That is, changing ecosystems that alternate destruction and life.

Those meticulous and vivid images that Halliday reconstructs from the past have only been possible thanks to the scientific advances of recent decades. «Recreating the worlds in which fossils were deposited, and in which the organisms that created them lived, is a challenge that paleontologists have tried to respond to since the 18th century. When I was little, the dinosaurs in books appeared colored according to how the artist saw fit, but now we know the real colors they had, and we have even been able to find out the sound that prehistoric crickets produced or what diseases some animals and plants suffered from. The entire book is based on that scientific evidence and, when there is something for which there is no proven data, I avoid talking about it rather than speculating. In reality, the really difficult thing has been synthesizing all that information to put together a story that made sense,” says Halliday, who has dedicated the last three years of his life to this project.

‘Other worlds’, on the other hand, is not only a look at the past but also an invitation to reflect on the present and a small window to the future. If we compare our world with that of the late Permian, we find worrying similarities such as the loss of oxygen from the oceans; while global warming brings us closer and closer to the Earth’s greenhouse periods, such as the Eocene. What all of these historical periods share is that they disappeared. Are we also destined for extinction?

Halliday responds: “We know that when the climate changes, worlds and life forms can be lost completely. That should make us aware that humans are not intrinsic to life on Earth. We are an important part of it at the present time, but we can easily disappear and be replaced by other forms of life, as has been happening for centuries with other species. That should really motivate us to preserve the climate and protect the ecosystem that we have, because although life is consistent, ecosystems are very fragile, and it is crazy to think that we will not be affected by the changes that we are imposing on the world. It is a decision that we have to make day by day. We can choose to destroy everything, and I hope we don’t, but we also have enough knowledge and technology to stop and minimize the damage. We often say we have 10 years left to solve climate change, but those kinds of timelines don’t work. We have already changed and lost a lot. “The longer we wait, the worse it will be.”

De-extinction is not the solution

Change is inevitable and thanks to it we are here. If a meteorite had not wiped out the non-avian dinosaurs, the diversification of mammals, including humans, would not have occurred, but “humanity is part of the world as it is right now, if that changes there may no longer be a place for us.” », warns Halliday.

Despite everything, there is still hope. In fact, we have already seen some examples of how life adapts to the new realities that emerge. For example, fungi and bacteria have been discovered that have evolved to be able to digest plastic waste, the problem of overpopulation is limiting itself with the decline in birth rates, and we have even had to live through a pandemic that many have considered the pause that the Earth imposed on us to try to “heal itself.” “Nature is pure invention,” maintains the author, “but that does not imply that the planet can infinitely maintain the wasteful lifestyle that economically developed nations now enjoy.”

It is in some of these nations that, at the same time, efforts are dedicated to the de-extinction of species. An example is the proposal of the American biotechnology company Colossal, which aims to use CRISP genetic engineering to ‘resurrect’ the woolly mammoth. Halliday disagrees. «Even if it were technologically possible to bring these animals back, it would be to a totally unknown environment for them in which they would not know how to function, which seems to me to be a terrible idea in ethical terms. Your time on Earth is over. “I think we should try to preserve the ecosystems that currently exist, which are just as incredible and fantastic, rather than reviving those of the past.”