Are we alone?

Is our presence here on Earth a one off or was the emergence of life inevitable?

A new postgraduate programme will train researchers to understand life's origins, search for habitable planets and consider the most profound question of all.

"The question of whether we are alone was once only the preserve of religion and philosophy but has recently become central to the natural sciences. We are now on the cusp of finding the answer."

Professor Oliver Shorttle

Film: Explore Planetary Science and Life in the Universe at the University of Cambridge

A new MPhil programme at the University of Cambridge will deliver postgraduate training in the search for life’s origins on Earth and its discovery on planets beyond Earth.

The course will explore the requirements for life’s beginnings: from its astrophysical origins to the emergence of biospheres, providing the essential knowledge for research in planetary science and life in the Universe. 

"This is a unique course delivered at a unique time," says course Director Professor Oliver Shorttle. "It will train a new generation of scientists who think across disciplines and drive a new period of discovery in the search for knowledge of life’s origins and presence in the Universe."

The new MPhil has been designed by leading scientists from the Leverhulme Centre for Life in the Universe, which brings together researchers from across the University of Cambridge to enable cross-disciplinary research on the origin, nature and distribution of life in the Universe.

Almost 30 years ago, Cambridge's Didier Queloz, who leads the Centre, discovered a planet orbiting another sun (an exoplanet) while he was a PhD student in Geneva. The Nobel-prize-winning discovery raised the possibility of Earth-like twins that are warmed by their Sun and where life could exist.

"Today, the search for the origins of life have taken us to reconstructing Earth’s earliest moments where chemistry became life, to probing the atmospheres of distant exoplanets for evidence of living organisms, to investigating ancient lake sediments on our neighbouring Mars, to seeking answers in philosophy to our most profound questions," says Shorttle, who is jointly based at Cambridge's Department of Earth Sciences and Institute of Astronomy.

Recently an international team of astronomers led by the University of Cambridge published the first evidence of carbon-based molecules in the atmosphere of an exoplanet, raising the possibility of potentially habitable worlds elsewhere in the Universe.

Film: Carbon-based molecules found on 'water world' exoplanet

"Astronomers have given us the 'black dot' of known exoplanets, and we are now edging towards more complete, colourful pictures of their pasts and their possible futures," adds Shorttle.

"This requires the help of chemists, zoologists, plant biologists, earth scientists, physicists and philosophers. This MPhil programme is exciting because it's the first time that researchers from so many disciplines are tackling the question of life in the Universe."

We meet some of the community engaged in this research here.

What can White Dwarfs tell us about habitable planets?

"Our planet Earth is the only planet that we know to host complex life (us). What was it that happened during Earth's history to make it the habitable planet that we live on today?

Our work looks to planetary systems beyond the Solar System to explore how a planet's history leads to its final properties.

Key to building a habitable planet is having the right ingredients. But finding out what a planet hundreds of light years away is made from is not easy. Our group makes use of a special phenomenon whereby old stars, White Dwarfs, reveal what exoplanets are made from. "

Dr Amy Bonsor, Institute of Astronomy

Planet graphic

Listening to the chemistry of life

"Chemistry is like a symphony. Each reaction, like a musical instrument, must work together in harmony for the symphony to emerge, rather than a cacophony.

The chemistry that leads to life's origin must exist in harmony. The metabolism that life uses today appears impossible to harmonise without enzymes, and there were no enzymes before there was life. Can there be harmony in other prebiotic chemical networks?

This is what we do: we find out where chemistry can be harmonised. Where this is not possible, we work to identify what would need to be changed in the chemistry in order to bring the chemistry back into harmony. In this way, we will better understand the first chemical steps that occurred to generate life."

Dr Paul Rimmer, Department of Physics

DNA graphic

Are we unique in the Universe?

"We investigate the role of environmental conditions in facilitating the origins and evolution of life. To do this, we use theory, experiments and field-based observations to look at the chemistry of natural waters on the modern and ancient Earth, and on ancient Mars.

We have used this approach to unravel the co-evolution of seawater chemistry and climate through Earth’s early history, and to reconstruct ancient environments on Mars through our involvement in the Mars 2020 Perseverance Rover mission.

We connect chemistry with the Earth and Planetary sciences in order to help understand whether the Earth, and the processes that made life possible, are unique in the Universe."

Professor Nicholas Tosca, Department of Earth Sciences

Planet graphic

Is there a planetary recipe for life?

"We investigate how planets come to harbour life: what happens during their formation so that life may eventually emerge from chemistry on their surfaces, and how they operate over billions of years to maintain conditions amenable to life.

These questions have led us to date when the building blocks of planets were crashing into each other in the earliest solar system, to the clouds of Venus where we estimated how much life could be supported there, and out to planets beyond our solar system, where we have identified how much life-essential water they may store in their interiors.

Our research provides a bridge from the Earth and Planetary Sciences to exoplanets in our quest to understand life’s origins and ubiquity in the Universe."

Professor Oliver Shorttle, Institute of Astronomy and Department of Earth Sciences

Planet graphic

Could life evolve differently elsewhere?

"Our research investigates the nature of evolution – how different ecological and biological processes lead to the diversity of life we have today. 

A key focus is understanding the origins and evolution of early animals from 600 million years ago, and the extent to which random chance leads to the evolutionary patterns we observe. 

To understand the nature of life outside the Earth, we need to understand how evolution proceeds in different environments, such as temperature or oxygen levels – and crucially how it may be different elsewhere.

If we find life on an exoplanet with a similar planetary configuration as Earth, and a similar age, will there be humans?"

Dr Emily Mitchell, Department of Zoology

Vegetation graphic

Would we recognise an alien?

"The search for life elsewhere in the Universe is tangled up with a series of deep conceptual questions. Some of them concern the very idea of what it means for a thing to be living, and the closely related question of what it means for a system to evolve and adapt.

The prospect of life originating independently on another planet raises the exciting possibility that alien organisms might have features that are completely different to anything we will ever encounter on Earth.

But there is a pessimistic worry tied to this exotic prospect: even if we were to encounter alien organisms, is our conception of what it is to be living so parochial that we would fail to recognise them as alive?

Might the same go for similar questions about the general nature of evolutionary adaptation, and the transition from non-living to living systems when life first emerges? These issues are all informed by work in the philosophy of biology."

Professor Tim Lewens, Department of History and Philosophy of Science

Book graphic

Join the search for knowledge of life’s origins and presence in the Universe

Published 18 September 2023

Written by Louise Walsh
Images courtesy of Amanda Smith – Institute of Astronomy

The text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License