Cosmos: Some of the Things that Molecules do

Neil deGrasse Tyson begins the second episode of Cosmos: A Spacetime Odyssey with the claim that

"This is a story about you, and me, and your dog."

But really this entire programme is about evolution; it's about taking on those that deny evolution is true and essentially calling them out for being the cunts they are. It's just that Tyson takes an hour to do it in a reasoned, eloquent way.

Before talking about evolution by natural selection he shows an example of artificial selection - the breeding of dogs from wolves. This took place over 10-15,000 years, as opposed to the hundreds of millions of years that evolution operates over.

The first example of evolution by natural selection that Tyson chooses is the brown bear becoming the polar bear during the ice age. This occurs by random mutation in the DNA during cell division, which happens to create a bear that is better fitted to the icy environment with a white coat than a brown one.

Tyson then moves on to debunking the classic claim of the anti-evolution, pro-Intelligent Design believers that the human eye is too complicated to have evolved therefore must have been Intelligently Designed.

Big Gay Longcat's eyes definitely were Intelligently Designed, thus proving the existence of the Maker of Cats.

Tyson takes us through the development of the eye as life itself evolved, from light-sensitive bacteria to flatworms to fish. A fascinating insight - one that I was not previously aware of - is that, because eyes evolved to see in water, no eyes since animals evolved to live on dry land have been as good.

That subject dealt with, Tyson introduces the concepts of the Tree of Life and the Halls of Extinction, ways of portraying (respectively) the metaphors of the descent of all life by way of evolution from common ancestors, and the huge number of species that have lived and then become extinct over the history of the Earth.

The Halls of Extinction will be revisited later in the series, but in this episode Tyson uses them to explain about the five mass extinctions that have taken place in the last 500 million years, each of which is represented by a Hall. The worst of these was the Permian extinction, about 250 million years ago, when c.90% of all species died out and it took life 10 million years to recover.

As the end of the programme approaches, Tyson takes the Ship of the Imagination to Saturn's moon Titan - the only world in the Solar System (aside from Earth) to have rain, rivers, lakes and seas... but of ethane and methane. He speculates about what kind of life might evolve there. It is a short and inessential part of the episode, a tangent from the main theme although still on the topic of life and evolution. The graphics of the Ship diving into the Titan sea are beautiful, though.

The last words in the episode come from Carl Sagan, repeating the 40-second animation of the evolution of life on Earth from the original Cosmos series.

I suppose that they considered this short piece to be strong enough to not need updating.

The highlights of this episode are definitely the initial section on dogs and the piece on the eye. As I mentioned, towards the end it gets a little fragmented and the strong theme is diluted a little. But the central argument has already been made by this point (natural selection = true, Intelligent Design = bollocks), so you could see these later sections as just interesting tangents or supporting side-themes.