I was fascinated, as always, to hear Paul Davies talking about the origins of life, this time on Radio National's Science Show. It was a great show all round - part two of a fascinating astronomy special linked to the Music of Cosmos event staged by University of Sydney.
Davies, now at Arizona State University but based in Adelaide for a while in recent years, was talking about what he terms 'weird life'. He thinks finding life elsewhere in the universe is unlikely, or at least not to be necessarily expected, but worth investigating.
He makes a good point about not confusing the number of earth-like planets with the number of planets that have earth-like-life, or indeed any life. There is more to life starting and evolving than finding 'goldilocks' planets like ours - i.e. just right in terms of having water and being a goodly distance from a star.
But more interesting are his ideas for testing here on earth for 'alien' or 'weird' life. What he means is that there may be life that has evolved separately to all the bacteria, bugs, algae, flowers, fungi and people that populate this planet. If such life could be found then we might argue that if it can happen twice on a near-perfect planet like ours, it could happen elsewhere. If not, well we go on searching.
It's complicated of course and this weird life might be living in extreme environments were regular life can't live - e.g. very, very hot places; very radiated places; very acidic places; and son on. Or it might live just under, or as Davies puts it, even in, our noses.
An obvious question is even if we find such weird life (with perhaps different DNA, different amino acids, different chemical symmetry) how do we know it isn't just an off-shoot of the same family tree during a long experimental phase at the beginning. There are tests for this but it does depend on life beginning with a bit of a bang rather than a draw out fuzzy period. And of course the weird life might be extinct now so we need to also search through historical remains of life.
Download or listen on-line to this Science Show (and while you are at it, the previous one - these astronomers and astrobiologists are exciting presenters). It's definitely a feast for the brain.
Maybe I'm more interested in this kind of thing because I work on relatively weird life - that is, algae - but I think the diversity of life forms on earth, and the way they evolved, are fascinating.
By the way, my picture is of a bromeliad, Aechmea gamosepala, which is coming into flower at my front door at the moment. Not necessarily weird life, but weird looking.