How did life on Earth begin?

Think about our precious blue planet - at the moment we’re enjoying variations of weather and distinct seasons as we spin around the sun on a lop-sided orbit. As it happens, we wouldn’t even have seasons if the Earth wasn’t spinning on a tilted axis. Supposedly the reason for this tilt is that our infant Earth was once hit, around 4.51 billion years ago, by a huge rock called Theia. This rock was so massive it effectively knocked our entire planet off-kilter. Then the scattered dust and rubble from this impact was hurled into our orbit, which in turn formed the Moon. Over time the Moon's gravitational pull changed the rate of the Earth’s rotation, while the titled axis caused different parts of Earth to recieve various patterned intervals of solar energy. This is what created the specific conditions for live to evolve.

So we often think of the sun as the cause or source of life, but it took a series of events to jostle our planet into position for it to then accommodate life. Then, over the course of billions of years, life began to flourish. From the little yawning hatchling to the colossal blue whale - all life vied for their share of this solar energy, currently beating down on us. Some species found ways of working together to harness their portion of this energy, others preferred a more solitary path. The why behind all this is deeply baffling. Maybe a big celestial being flicked the rock of Theia at us like a huge marble. Or maybe this is all just a wild, happy accident. Who can say? What’s more interesting, I think, is the way in which this precarious, infinitely complex series of consequences has led to us existing here, right now, as we do…

A couple of years ago I had no idea that such an impact had occurred. I think I just assumed that Earth formed and somehow developed these conditions on its own. However, reading about Theia reminded me how little I understand about the world in which I live. The same thing happened to me again more recently. Whistling in blissful ignorance, I put on a documentary called Chasing Coral and suddenly realised, aside from owing a thank you letter to Theia and the Moon, we now also had to include a P.S. for phytoplankton as well. 

About a week earlier I’d never even heard of phytoplankton. Now I discover that fish, whales, dolphins, seabirds - in fact, all life on Earth, are able to live and breathe because of this single-celled superhero plant, bobbing on the ocean surface.

As it turns out, phytoplankton is a type of plankton that produces energy through photosynthesis. It is also food for zooplankton, another type of plankton, which feeds and supplies energy for countless marine creatures, from darting fish to slow-moving whales. This plankton then travels up the food chain until it finally reaches us - the apex predator. At the moment, plankton is the primary source of nutrition and energy in the ocean. Unfortunately, it is being hit hard by the twin-pronged, man-made catastrophes of climate change and pollution.

As the oceans warm and as we continue to produce waste and pollution, plankton are being forced to adapt and this adaptation has terrifying consequences.

Firstly, excess nutrient inputs, caused by the nitrogen and phosphorous of agricultural land operations, are entering the ocean and upsetting the ecosystem. Phytoplankton takes on these extra nutrients and their numbers increase dramatically. This shifts the settled pendulum too far in one direction and leads to coastal areas being infected with the greenish ooze of algal overgrowths, many of which are potentially toxic, sickening and killing other marine animals.

Secondly, the amount of plastic we dump in the ocean (it was recently predicted that by 2050 there will be more plastic in the ocean than fish) has actually caused zooplankton to start eating plastic. Microplastics (tiny traces of plastic) look a lot like the usual food of a hungry zooplankton, but, unlike their usual food, they contain toxic chemicals. These chemicals are then passed up the food chain, which is terrible news for ocean life and for us land-dwellers too!

So, you remember I mentioned earlier that phytoplankton is something of a superhero plant, helping us to breath? Well, this is because it takes on carbon dioxide and uses solar energy to convert it into nutrients through photosynthesis. In order to perform this photosynthesis, phytoplankton must have energy from the sun and nutrients from the water. If it has both these things, phytoplankton performs the process of photosynthesis and releases oxygen into the water. What's really crazy is that half the world's oxygen is actually produced in this way.

As they say on Chasing Coral: We owe every second breath to phytoplankton. The other half of our oxygen is produced through photosynthesis on land, performed by trees, shrubs, grasses and other plants.

Today, plant life and phytoplankton keeps a balance in the amount of oxygen it produces. Healthy forests use carbon dioxide from the atmosphere to create oxygen through photosynthesis, which is then needed for further growth. In other words, it's a healthy, self-perpetuating system. Indeed, most ocean and land photosynthesis is counterbalanced with an equal and opposite amount of breathing. 

Often we talk about how oceans, especially when you swim and dive in them, are life-giving in the internal psychological or even physiological sense. And yet we often forget that our gratitude should go deeper - the oceans are literally responsible for life on Earth. For me, this was just another jarring reminder that the natural world isn’t just an amusing sideshow or buffet – it is an ancient, inexplicable life support system and without it we’re all fucked.