Now that a helicopter has flown on Mars and oxygen is being manufactured there, children today might start imagining themselves on the Red Planet—going to school, tending plants and playing sports in 38 percent of Earth gravity. It feels almost inevitable that humans will eventually land there, building small biospheres with plants, microbes, and humans intertwined in a tightly controlled ecosystem. When we go, we will bring some of Earth’s species to Mars, such as the microbes on our skin, and we might even find some life already there.

Yet, if we do find organisms on Mars, they will likely fit into the same three categories of species in ecosystems here on Earth: 

(1) Producers (e.g., plants, algae);

(2) Consumers (e.g. snails and squirrels to fish and humans); or

(3) Decomposers (e.g., fungi and many microbes).

All three types of creatures have been shuffling carbon, energy, and nutrients between each other on Earth for billions of years. For all of history, species in all of our planet’s ecosystems could be placed neatly into one of these three buckets.

However, in 1796, that changed forever. In that year, Georges Cuvier gave a lecture in Paris, “On the Species of Living and Fossil Elephants,” where he noted the curious fact that elephants he saw then were radically different from the ancient woolly mammoth fossils that had been found in the world. Since no living woolly mammoths could be found anywhere on Earth, he wondered, perhaps they were all gone? Not just one mammoth had died, or many, but all of the mammoths had perished, never to return again.

The simple, but powerful, concept of extinction was born. This work was noted by Charles Darwin in his 1859 book, On the Origin of Species, where he proposed possible mechanisms for the birth, change, and death of species. This awareness of extinction led to an extraordinary new ability for humans, that is (as far as we know) still completely unique to humans; we can monitor, prevent or accelerate extinction itself. We are “extinction aware.”

Sadly, even with “extinction awareness,” humanity’s track record on preventing extinction is bad. We ate some species to extinction like the woolly mammoth, sea cow, and Eurasian auroch, and others we hunted to extinction like the dodo and passenger pigeon. It is now estimated that one million species may be lost due as a result of human activity, and one of every four birds in North America is now gone due to hunting and habitat destruction. The time for greater awareness of extinction has never been more urgent.

As the only species with an awareness of extinction, only we can prevent it. We thus represent a new, fourth category of species : Guardians.

Guardians of an ecosystem have a duty to serve as protectors of the life within it, as well as beyond it. Some of this we already do already today. We track and restrict invasive species across borders, nurture endangered species back to health, and set up nature preserves around the world. There is even an ongoing effort to bring back woolly mammoths from extinction with the Revive and Restore project.

While our duty as Guardians is self-appointed, the massive hubris of this effort does not obviate its absolute necessity. Also, only a self-aware species can become Guardians, so such a duty will likely always be self-appointed, and is the only duty that is activated upon awareness.

Fortunately, the act of going to Mars gives us a new lens through which we can better understand and protect life’s fragility and to avoid extinction. Indeed, going to Mars is the best way to ensure humans and other organisms are present on more than one planet. Planetary Protection protocols, which prevent contamination to Mars (or vice versa) stipulate that we must go carefully and aim to disrupt as few places as possible.

Without any guidance or protection from a Guardian species, we know what happens. In an unguided, “natural” cycle of ecosystems, including invasive species and asteroids, massive waves of extinction and rebirth occur. Large extinctions thus far include (with the percent of species lost):

Ordovician-Silurian, 440 million years ago, (85 percent)

Devonian, 365 million years ago (75 percent),

Permian-Triassic, 260 million years ago (96 percent),

Triassic-Jurassic, 200 million years ago (80 percent),

Cretaceous-Paleogene, 65 million years ago (76 percent, including the dinosaurs).

So far, we have been lucky, but that luck will not last forever. Even if we have achieved perfect world peace and sustainability on Earth, eventually (about a billion years) the sun will further enlarge and start to char the Earth. 

All ethical questions become crystal clear in the time frame of a billion years. If you value life, or anything that life creates, we will have to move beyond Earth. We will need to go to the Moon, then Mars, and then farther, to preserve life. And since life is not yet adapted or able to survive, we may need to engineer life in order to save it.

To become truly, sustainably multiplanetary and perhaps eventually multi-stellar, humankind must rely not only on rockets and computers and space habitats, but also upon the transformative power of genetic engineering to adapt terrestrial biology to the alien environments beyond Earth. Our duty to the stars requires considering and likely using the evolutionary lessons inscribed in the DNA of not only our species, but all others. We may need every adaptive trick from all the extremophiles we know of to survive the new planets we may encounter. We may need to re-activate capacity in our own DNA, like the ability to synthesize our own Vitamin C, which some primates still carry. Eventually, we can even learn from organisms that evolve and change on Mars, or other planets, and bring those lessons back home to survive.

All biology, given enough time, is space biology. Any goal of any kind requires survival to be enacted, and thus survival is the primordial duty and ethic antecedent to all others. Our duty is not only for our own survival, but for all species that exist, that have existed, and that will exist. We are the first, and thus far, the only, Guardians of life.

If we find no life on Mars, or anywhere else, then life is that much rarer and more precious. But, even if life is found on Mars, there too we have a Guardian duty to protect and preserve it, since it likely cannot do it by itself. This duty will give both a catalog of life, as well as an expanded genetic toolbox for survival. Each creature we come across in this universe or any creature that adapts and evolves on a new planet may hold the clues of adaptation and evolution to help other life (including us) avoid extinction.

Our role as Guardians, as this unique, fourth kind of species, is just starting as we explore Mars more and more, and as we continue to catalog and preserve Earth. This unparalleled time of space biology and planetary exploration (including exoplanet discovery) and genetic mapping is not Plan B. It is Plan A. It is our duty.

This essay is adapted from the author’s new book The Next 500 Years: Engineering Life to Reach New Worlds.

This is an opinion and analysis article.