LUCA latest (Introduction)

by David Turell , Tuesday, July 26, 2016, 15:08 (3040 days ago) @ dhw

dhw: In this context, I was struck by the following quote:
> 
> "He argues that Luca is very close to the origin of life itself. The organism is missing so many genes necessary for life that it must still have been relying on chemical components from its environment."
> 
> I don't know about you, but I find it pretty hard to imagine our poor old LUCA sweltering in his deep sea vent, lacking all those genes, and yet at the same time possessing all the information needed to become an Eskimo living in Alaska.-Please remember LUCA is a theorized close-to-the-origin animal, based on genome studies and assumptions, not a real discovery. It makes the assumption that evolution went from a few genes to many which is most likely true. From the article:-"Their starting point was the known protein-coding genes of bacteria and archaea. Some six million such genes have accumulated over the last 20 years in DNA databanks as scientists with the new decoding machines have deposited gene sequences from thousands of microbes.-"Genes that do the same thing in a human and a mouse are generally related by common descent from an ancestral gene in the first mammal. So by comparing their sequence of DNA letters, genes can be arranged in evolutionary family trees, a property that enabled Dr. Martin and his colleagues to assign the six million genes to a much smaller number of gene families. Of these, only 355 met their criteria for having probably originated in Luca, the joint ancestor of bacteria and archaea."-Finally, remember that these genes must contain information on how to evolve. All the probably correct genes may not have been chosen.