Mysteries of Life, on Earth and Above

In Conversation with Geologist Dr. Sami Mikhail

Perched in an airport, corner bar seat, or some eyrie overlooking a crowded street, many will have written the stories of strangers' lives — guessing where they come from, who they love, or where they are going.

Dr. Sami Mikhail, a reader in the School of Earth & Environmental Sciences, nods to similar musings when he looks up at the night sky. But his storylines transcend the heartbreak and histories of humanity. He wonders: what stars — with light years separating time and space between them — have already exploded into cosmic dust? What life form might be looking back down at him? “I see the night sky like that", he says.

Mikhail is among the Earth & Environmental Science faculty that seek to explain our planet’s history and the broader cosmos. They share that pursuit with undergraduate students through a new course on ‘astrobiology’: the study of the origin, evolution, and future of life in the universe. Founded by Dr. Claire Rachel Cousins, who normally runs the course but is currently on maternity leave, ES1006: Astrobiology: The Search for Life in the Universe teaches the interdisciplinary study of past and present habitable worlds. It investigates aliens — from the utterly fictional to the plausible — biology in space, and the implications of looking for extraterrestrial life within philosophy, international relations, science fiction, and more.

To Mikhail, the course — and his own work — has a simple overarching aim. “It’s about asking: why the f*ck am I here?” he says. “And actively trying to understand: how did that happen?”

To date, that question remains as unanswered as ever. “But before you can even get close to why, you need to understand how”, Mikhail says. “And if we can understand how life came about, then we can look for it.”

I spoke to Mikhail — who is currently attempting to further quantify the history of earth’s atmosphere — about his work, the astrobiology course, and the state of the search for extraterrestrial life. He offered insights into exciting new strides in space exploration and the hurdles still hobbling it, revealing that — while living lifeforms are likely out there — finding evidence of extinct microorganisms is the most probable way we will ever make contact with ‘aliens.’ That search for life, nonetheless, requires insights from a plurality of fields, he says — ranging from the humanities to the sciences.

A geologist by training, Mikhail began our conversation by placing two rocks in my hands to demonstrate his field's role in answering our most central unknowns. The first: a two-year-old sample of hardened lava from Iceland. The second: a piece of the oldest rock on earth, a 4.013 billion-year-old sample of “gneiss” collected from Northwestern Canada. “If you hold these in each hand, then between that rock forming, and that rock forming, life starts and becomes evolved to now”, he said. “So what happens between them? That's what geology [tries to answer].”

Rocks hold clues to Earth's history, allowing those — like Mikhail, who can interpret them — to discern how the planet has evolved and formed its atmosphere through the volcanic spews it omits from its core. Mikhail himself deconstructs minerals, and mineral assemblages, to estimate the makeup of Earth’s atmosphere and determine whether it shrinks or grows over time.

“In the same way that the doctor might look at your poop to help check on your colon, I’m looking at earth's poop to understand what's happening in its colon”, Mikhail says. “What happens inside controls the gas that comes out, and the gas that comes out, both forms — but also modifies — our atmosphere.”

By performing a ‘planetary colonoscopy’ on earth, Mikhail hopes to quantify its atmosphere, allowing researchers to compare it to that of planets like Venus — which has a similar size and composition — and explore how the two diverged, leaving only one habitable. “Why is earth so lovely for life?” Mikhail says that is what he is trying to answer, for it poses another question: “Are we the only planet like that?”

A stronger grasp of what makes Earth’s atmosphere unique would contribute to the search for ‘exoplanets’ — planets beyond our solar system — by providing astronomers with the tools to search for similar atmospheric conditions elsewhere. “If you can find definitive proof [of what] led to a change on Earth that made it more suitable to hosting long-term life, even that would be amazing”, Mikhail says. “Rather than cataloguing planets solely on mass and distance, we would have another variable, which is chemistry.”

Exoplanet research has amped up in recent years as space telescopes have become more sophisticated. What exoplanets can be identified and the quality of research into them is likely to improve in the coming years. But extraterrestrial quests are staggered by technological limitations. Even if a spacecraft left Earth at the speed of light, 97 per cent of the observable universe — which contains some two trillion galaxies and innumerable stars and planets — would be unreachable. “Statistically, the likelihood of us being the only place that life started seems improbable, to the extreme”, Mikhail says. “But space is annoyingly vast.”

Humans are far from the technology common to shows like Rick and Morty, where ‘portal guns’ help cosmic travellers skip across universes and galaxies. And while our best imaginations conjure up futuristic space technology, even our best minds lack the mental elasticity to conceptualise the mirror-like infinity of outer space. “We look for life as if tied to a chair. And we are told that to invent new techniques, we need to run from that chair”, Mikhail says. “It's just not possible.”

Geology is the key to what Mikhail believes is “probably the most tangible way we’ll ever find life”: where it is extinct. The search for extinct life has accelerated in recent years — especially on Mars, where evidence suggests there was water conducive to microorganic life some three to four billion years ago. That search had yielded nothing conclusive yet. But it is still the most likely avenue of extraterritorial discovery. “If there was life in the solar system — be that on Europa Mars, Venus — we’re probably more likely to find that than aliens”, Mikhail says. “Because it would be preserved in the rock record.”

The search for extinct life begs an important question: how alone — and how exceptional — really are we? “There are two ways of asking that question”, Mikhail says. “Are we alone presently, as living organisms, or are we alone fundamentally, as the only life that ever happened?”

Mikhail has been exploring such existential ponderings since childhood, when the Natural History Museum in London and David Attenborugh’s sonorous voice first wrapped him in wonder. He recalls his scientific infancy: travelling to North Africa with his Egyptian father and wondering why “Egypt was yellow” and “England was Green.” He recalls when he first peered beyond the shroud of light pollution that hides the night sky in South London. “If you go out into the desert, there's no humidity, there's no clouds”, he says. “The sky is glowing at you. It's beautiful.”

As a student, Mikhail became fixated on the ‘Big Five’ mass extinctions, marvelling at facts like how, some 300 million years ago — when oxygen made up 35 per cent of the air, compared to the 21 per cent we breathe today — millipedes stretched metres and mosquitoes were like small dogs. “Terrifying world”, Mikhail notes. Propelled by his natural aptitude for science and maths, Mikhail investigated Earth’s history until finding his place in the search for meaning and more in petrology.

But reckoning with life’s fundamental questions takes more than just geologists. It requires a conglomerate of thinkers — including chemists, biologists, astronomers, philosophers, and more — in a mighty campaign for answers. “This isn't a movie. No single genius is going to figure any of this out”, Mikhail says. “It's a team sport, and it has to be a team sport.”

H.G. Wells's stories and blockbuster movies like ET, Star Trek, Avatar, and more, all demonstrate the broad reach of astrobiology. They reckon with questions like: how should we interact with other lifeforms? Do extraterrestrials have rights? Are they intelligent? It goes on. “Nobody is excluded from the hunt”, Mikhail says. “Everyone can contribute to trying to understand where we come from and why it matters.”

The astrobiology course accordingly delves into a wide range of content, even drawing in a guest lecturer from the International Relations department that specialises in ‘space law.’ Its coursework reflects that multidisciplinary interest: a sample exam question, for instance, asks students to write a “fictionalised account of the discovery of extraterrestrial life” and the “shift to a new paradigm” that would follow.

“[The course] asks maybe the only question that is universally interesting”, Mikhail says. “Why is there life on Earth? I don’t think there’s a single human being, with a brain in their head, who doesn't just think that's really cool.” He asks readers to respond with a more engaging query if they can.

Mikhail adds that thinking about the humbling shades of our universe holds pertinent wisdom, showing us that we ought to be kind and never take life seriously. “When you look at humanity, and our geopolitics and our international relations — you think, guys, we're all stuck on the same little rock”, he says. “What are you doing?”

That perspective makes polluting our planet, for instance, seem nonsensical. “It’s like throwing sh*t out your window. And then getting really annoyed when the smell starts coming in every time you open the window”, Mikhail says. “You know you're putting sh*t outside.”

But the mosaic of humanity’s collective progress, for all its faults and follies, contains much worth admiring. “So yes, we're volumetrically insignificant. Our lives mean nothing”, Mikhail says. “But when you accept your insignificance as a single entity who can do something — we’re actually quite powerful.”

Illustration: Lauren McAndrew