Playing god

Craig Venter's work has hit the headlines again. Its exciting stuff, but rather than going into the ethical issues that present from the first synthetic species created I want to pick up on what it means for the study of abiogenesis (origin of life).

A few years ago Venter's team produced the simplest form of life they could possibly manage by cutting bits out of the genome of a very simple bacteria. They kept on cutting bits out until they got to the point where if they lost any more genes then the cell just wasn't functional. The end result was a bacterium with a genome of around 500,000 base pairs. You could think of it as the lowest common denominator of life.

Now the team have stitched together a completely novel genome from scratch, but here's an interesting extract from an interview with Dr Venter:

How difficult was this?

At one time there was just one error in over a million base pairs, and we found that as a result you don't get life.

In explaining how complex a task it was Venter explains that anything worse than 99.9999% fidelity just doesn't work. That's astonishing. And when you combine it with the previous findings outlined above you realise that at root life is an exceptionally special and delicate phenomenon.

Common Descent

One of the main tenets of modern biology is the theory of universal common ancestry, or the idea that all living organisms can trace their genealogy back to mutual descendants. A recent paper has sought to further test that theory. It looked at the main domains of life (Eukarya, Bacteria and Archaea) and asked if their relationships are better defined by a unified common genetic relationship or by multiple lineages. The results were unequivocally in favour of UCA, but the introduction to the paper highlighted other, more general reasons for accepting the theory.

The evidence it listed was:
1) the agreement between phylogeny and biogeography
2) the correspondence between phylogeny and the palaeontological record
3) the existence of numerous predicted transitional fossils
4) the hierarchical classification of morphological characteristics
5) the marked similarities of biological structures with different functions
6) the congruence of morphological and molecular phylogenies
7) key commonalities at the molecular level
8) near universality of the genetic code

Marking on Eggshells

Overlooking the Verlorenvlei River in the Western Cape area of South Africa stands the Diepkloof Rock Shelter – a large sandstone feature. Earlier this year scientists reported that as a result of excavations they had uncovered 270 Fragments of Ostrich Shells 2-3 cm in diameter extracted out from the rocks. What was remarkable about these pieces is that they had been engraved.

This unique collection demonstrates not merely the engraving of a single geometric pattern but the development of a graphic tradition and the complex use of symbols to mediate social interactions. The large number of marked pieces shows that there were rules for composing designs

Texier et al Proceedings of the National Academy of Sciences April 2010

Using three independent methods the researchers established that the rocks layers they were found in are around 60,000 years old. So sixty millennia ago someone was employing themselves in the art of decorating eggshells.

Humans before Adam?