Tonight: Nova on Finding Life Beyond Earth

by Salman Hameed

The new NOVA episode is on tonight. Its on Finding Life Beyond Earth. Here is the preview, but I think full episode will also be available online. In any case, I will post it on Irtiqa this coming Saturday.



This is perfect timing as I'm co-teaching Astrobiology this semester with biochemist Jason Tor from Hampshire College and planetary geologist Darby Dyar from Mount Holyoke College. It has been a fun class so far. Just this past week we had a fascinating discussion over the work on the origins of life versus what we know about Last Universal Common Ancestor (LUCA). What is fascinating is that the date for LUCA can be estimated from what we know about genes, and is now estimated to be between 3.9-4.1 billion years. Still, we don't have much idea about the path (and perhaps some dead-ends too) between the first life form and LUCA. Absolutely fascinating!

While on the subject, here is a bit from a NYT interview with the 2009 chemistry Nobel Laureate, Jack W. Szostak. He is currently working on the problem of origins of life. Here are the relevant parts of the interview and it will give you a flavor of how researchers think about these issues:

What do you study now? 

The origins of life. In my lab, we’re interested in the transition from chemistry to early biology on the early earth. Let’s go back to the early earth — let’s say probably some time within the first 500 million years. And let’s say the right chemistry that would make the building blocks of life has happened and you have the right molecules with which you can spark life. How did those chemicals get together and act something like a cell? You want something that can grow and divide and, most importantly, exhibit Darwinian evolution. The way that we study that is by trying to make it happen in the lab. We take simple chemicals and put them together in the right way. And we’re trying to build a very, very simple cell that might look like something that might have developed spontaneously on the early earth.
How far have you gotten? 

Maybe I can say we’re halfway there.
We think that a primitive cell has to have two parts. First, it has to have a cell membrane that can be a boundary between itself and the rest of the earth. And then there has to be some genetic material, which has to perform some function that’s useful for the cell and get replicated to be inherited. The part we’ve come to understand reasonably well is the membrane part. The genetic material is the harder problem; the chemistry is just more complicated. The puzzle has been understanding how a molecule like RNA can get replicated before there were enzymes and all this fancy biological stuff, protein machinery, that we have now in our cells.
...
You’ve now been working on this problem for a quarter of a century. Do you ever grow weary of it? 

No. No. Because this isn’t a monolithic question where there’s nothing interesting until you get to the end. In fact, the question breaks down into maybe a dozen smaller questions. Each has interesting parts. Eventually it will all fit together.
For instance, we’ve made progress on the question of how you make a primitive cell membrane. Others had showed how a common clay mineral, montmorillonite, might have played a role in helping to make RNA. Our lab showed how it could help membranes to form and bring the RNA into the membrane.

Read the full interview here.