The Emergence of Life in the Universe
Written by Isla Madden
Our Universe is an enigma, yet as observers, we are compelled to understand it. To observe the cosmos is to witness creation—or at the very least, to attempt to locate ourselves within it. Creation set space and time in motion, and from this emerged the Universe as we know it. The Lambda Cold Dark Matter (ΛCDM) model is the prevailing cosmological framework, uniting our understanding of the Universe’s formation, structure, and evolution. Its history is a story of emergent complexity unfolding over nearly 14 billion years.
In its earliest moments, the Universe was a hot, dense, homogeneous plasma, with no structure—only energy and fundamental particles interacting under the laws of physics. As it expanded and cooled, recombination occurred approximately 380,000 years after the Big Bang. Gravity then drove the clumping of matter, drawing hydrogen and helium into dense regions that collapsed to form the first stars and galaxies. Within stellar cores, nuclear fusion produced heavier elements, later dispersed by supernovae, seeding the cosmos with the raw materials necessary for planets and, eventually, life.
The Solar System formed around 4.6 billion years ago from the gravitational collapse of a molecular cloud, producing a rotating protoplanetary disk in which the central mass became the Sun and solid particles collided to form planetesimals that grew into protoplanets. Within the inner disk, accumulating planetesimals formed early Earth, with high-energy impacts generating enough heat to differentiate a metallic core from the silicate mantle and crust. A giant collision with a Mars-sized body, Theia, is hypothesised to have formed the Moon and set Earth’s axial tilt. Cometary impacts and condensation of water vapour contributed to the oceans, establishing a stable environment with liquid water and tectonic activity essential for life.
Biological complexity emerged through evolution by natural selection, giving rise to diverse ecosystems, sentient life, and conscious beings capable of reflecting on their origins. The genus Homo emerged in Africa approximately 2–3 million years ago, evolving from earlier hominins such as Australopithecus. Homo erectus was the first to migrate out of Africa, surviving for nearly 1.5 million years, while Homo sapiens appeared around 300,000 years ago, rapidly dispersing and eventually becoming the dominant human species. Our emergence represents a brief but profoundly transformative chapter in Earth’s biological history.
The Universe’s earliest phases were marked by a series of distinct transformations shaping the cosmos as we know it today. Over billions of years, stellar evolution and chemical enrichment gave rise to complex planetary systems. As Marcus Aurelius wrote, “Observe constantly that all things take place by change, and accustom yourself to consider that the nature of the Universe loves nothing so much as to change” (Meditations 4.3), reminding us that even stars, planets, and life itself exist only temporarily within this ever-unfolding order.