The Urey and Miller Story

download (1)This here is Stanley Miller.

When you tell stories in science and make it relevant to students they remember it better. Let’s take this example of the story of Urey and Miller and how their revolutionary experiments have impacted our ideas on the origin of life on Earth.

My Origin of Life on Earth story

So the first thing you should know is that the Earth is really old. Really really old. It’s 4.5 billion years old. But how old is that? I don’t know! So let’s do something else. If we imagine that the whole time that Earth has been around to be 24 hours. Then we can work with a timescale that we’re a little more familiar with. Ready to join me? Okay.

So at 0:00 the Earth just formed.

At 2:35 am prokaryotic life (bacteria + archaea) form

Nothing much else happens till 4pm. Bacteria are just hanging out there. Making the world oxic.

At 4pm eukaryotic life appears. These are organelle bound remember.

Again, nothing much happens until 9:45pm where insects appear.

10:33pm Dinosaurs appear

10:54pm Mammals appear

11:57pm Modern Homo sapiens appear

1 second ago – first Aboriginal cultures appear

All of recorded history lasts only 0.03 of a second.

779d0b85e11cceb505f3310e0d0d87de

Mind = blown. That’s pretty incredible isn’t it?

So then let me introduce you to two men: Oparin and Haldane. These guys both independently hypothesised the conditions of Early Earth. Haldane goes hmmm I wonder if biomolecules began to exist on Earth as a direct result of the conditions of Early Earth. And Oparin goes: oh man! I thought of it first, but I didn’t publish it in English and so no one knew about it! *sad face*

What did they think Early Earth was like?

  • it was HOT
  • it was gaseous
  • there was no oxygen
  • there was a lot of water
  • there was a lot of lightening storms
  • there was a lot of UV radiation as there was no atmosphere

Now introducing another two guys. Harold Urey and his slave graduate student Stanley Miller. Mr. Urey says “Hmmm I wonder if I set up an experiment with all those conditions, would it give rise to those biomolecules? If only I had a grad student to do all this research for me….Oh Stanley!!!!” And Stanley of course says “Yes Boss”.

If you’d like to see a set up of their experiment this site has a fantastic video to explain it.

In my powerpoint I have a whole series of other useful questions to ask of your students regarding the Nature of Science.

The Scientific Method

So many of you will already be aware that there isn’t one scientific method. The one we usually learn and teach about however, goes a bit like this:

  • aim
  • hypothesis
  • method
  • results
  • discussion
  • conclusion

Looks familiar right? Now remember when I said there isn’t only one scientific method, let’s consider the field of epidemiology. In epidemiology which is a branch of biology we try to understand human diseases, how they originate, how they spread, what are some factors that predetermine the acquisition of disease and so on. Now it’s really frowned upon to do experiments on people. For example, we can’t PROVE that smoking causes lung cancer because we can’t say “Oi, you 30 people, come over here and smoke for the next 20 years of your life and we’ll see if you get lung cancer, and you 30 over there, you’re fine just don’t smoke”. I’m sure you can see how ridiculous that would be!

So how do we get around this problem? Well by a lot of observation. Epidemiology relies on life already carrying out the method and results, and epidemiologists just go out and try to observe people and find patterns. It’s a very complicated but extremely fascinating process that relies very much on statistics. I might do a post on the bell curve if I get a chance – it’s actually really cool.

So anyway, here is a template you can use with high school students to scaffold for them the (traditional) scientific method.

Can you think of another situation where the classical scientific method doesn’t hold true?

Scaffolding Scientific Method