Ice and the origins of life on Earth (Medium)

Hello. This is 6 Minute English from BBC Learning English. Im Sam.

Neil

And Im Neil.

Sam

you ever made a snowman or enjoyed a cold drink on a hot summers day? Slippery in winter and in summer, ice is made when water gets so cold it freezes. But theres much more to ice than holidays and cold drinks.

Neil

Yes, in an exciting discovery, the James Webb Space Telescope recently detected coldest ices ever in outer space, something Nasa scientists think could explain the origins of life on Earth.

Sam

For years scientists have debated how life started on our planet. Billions of years ago, long before the , animals or even plants existed, the Earth had a watery environment of oxygen-free gases and chemicals known as the soup. It had the potential for life to develop, but something was missing.

Neil

So how did we from the primordial soup to the first living plants, animals, and eventually humans? And how does ice fit into story? Thats what well be finding out in this programme, and as usual, well be learning some useful new as well.

Sam

But first I have a question for you, Neil. We know ice is frozen water, do you know the chemical symbol for water? Is it:

a) H2O ?*%

b) HO2 or

c) H2O2 ?*%

Neil

Well, I really hope I get this . I think the answer is H2O.

Sam

OK. Well find out or check if youre right later in programme. Astronomer, Professor Melissa McClure, worked with the Nasa scientists who found ice on Europa, one of Jupiters moons. she explains to BBC World Service programme, Science in Action, one theory linking ice to the beginnings of life Earth.

Professor Melissa McClure

There's sort of these two alternatives for how you could have had life arise Earth, and one is that the very basic building blocks, like water, and methane, and CO2  � like, those were definitely brought to Earth by ices in comets, and maybe once they were on Earth, then they reacted either geothermal heat or some kind of lightning strike to form more complex molecules.

Neil

Earths primordial soup the building blocks of life  � a phrase describing the most basic biological and chemical units needed to support things, elements like oxygen and carbon.

Sam

Professor McClure thinks these missing elements were brought to Earth in - large bright balls of dirt and ice which travel around the Sun in outer space.

Neil

Its that when comets hit Earth billions of years ago, elements in the ice were scattered and struck by lightning  � a bright flash of light produced by electricity moving in the atmosphere. This resulted in the complex molecules needed life on Earth.

Sam

Exactly how this happened is not known, but it involves biomolecules, molecules like DNA are found in living things. Ice is not a biomolecule, but when it mixes with carbon, the atoms in molecules change to produce complex molecules  � and thats when interesting things start to happen. Heres Professor McClure again, more to BBC World Services’, Science in Action.

Professor Melissa McClure

If they have a carbon atom in then theyre complex organic molecules, so things like very simple alcohols like methanol or ethanol, like what you would , are complex organic molecules. And these molecules could react and start a sort of a reaction chain that would lead to something like a biomolecule.

Neil

Ice can react with other elements to create organic molecules, for the alcohol, methanol. Here, the adjective organic means related to living plants and animals. Thats different from how we the word to talk about ‘organic food’, meaning food that hasnt been grown using artificial chemicals.

Sam

When organic molecules met the primordial soup - so the theory goes - it produced a chain reaction  � a of chemical reactions in which one change causes another. It was this chain reaction which created the first living and eventually, humans. Quite impressive for a little piece of frozen water!

Neil

Speaking of water, Sam, what the answer to your question about the chemical symbol for water? I said it was H2O.

Sam

was the right answer, Neil! Each molecule of water, and ice, contains two atoms of H, thats hydrogen, joined one atom of oxygen. OK, lets recap the vocabulary weve learned from the programme, starting with primordial soup  � environment on Earth before there were any plants or animals, which created the conditions for life.

Neil

The the building blocks of life refers to the most basic biological and chemical units needed to support living plants animals.

Sam

A comet is a large object travelling in space which orbits the sun and has a , burning tail.

Neil

Lightning is a flash of bright light produced by electricity moving in the atmosphere.

The adjective organic means relating to living plants and animals. And ‘organic food’ means food which has been grown using chemicals.

Neil

And finally, a chain reaction is a series of chemical reactions in which one change another, which in turn, causes another. Once again, our six minutes are up. Goodbye!

Sam

Bye bye!