by CKR
No, not the Secret Service, and not Russian ethnics in Estonia! This is a science post of a kind I haven't done for a while.
Some long time ago, Thomas Gold went outside his field of astrophysics to suggest that petroleum was not the remains of dinosaurs or algae, but was formed from inorganic materials deep in the earth’s crust, an abiogenic origin, meaning without the intervention of life. Russian scientists have proposed similar origins of petroleum. A consequence that some have drawn from this idea is that petroleum is essentially inexhaustible. More recently, the petroleum pessimists have prevailed.
One of the arguments for dinosaurs and algae (more the latter than the former) as the source of petroleum is that complex molecules produced only by living things are found in petroleum and have been used, commercially, to figure out which rock formations the petroleum formed from and therefore where there might be more.
Gold’s response to that was that bacteria love to eat that abiogenic petroleum. He extrapolated that there must be lots of bacteria we’ve never met deep below the surface of the earth. The definitive experiment was supposed to be the drilling of the Siljan impact structure in Sweden. I’m not googling up any really wonderful links; what I recall of the results was that trace amounts of hydrocarbons were found, but nothing like what Gold had predicted. Some bacteria were found that might have been feeding on the hydrocarbons, but drilling technology at that time wasn’t sterile, so the bugs could have come from anywhere.
Some scientists continued to wonder how deep life might go, and they developed methods of keeping drilling cores reasonably uncontaminated by the bacteria that are around and in us all the time.
The 10 November Science magazine contains an article on microbes in cores drilled from sediments under the sea. It turns out that bacteria and the somewhat similar archaea live in those sediments all the way down to the bedrock of the ocean. They may constitute a fifth of the total bulk of life on earth.
They’re peculiar bugs, or maybe the scientists are missing something. These bugs seem to live very slowly: calculations indicate that they divide only once in a thousand years. This seems too slow to keep the fire of life burning, but other tests seem to show that the cells are indeed living.
Investigations will continue, of course. DNA analysis will proceed, and attempts will be made to culture the microbes and figure out what they’re eating.
Speaking of deep microbes, a group of researchers from institutions across the United States reported a “Metagenomic Analysis of the Human Distal Gut Microbiome” in the 2 June Science.
We’ve long known that we have lots of bacteria living in our guts. They help to digest food and provide us with some nutrients that we don’t get any other way.
This study did DNA analysis of human feces. The researchers were able to determine the families to which the gut bacteria belong and what kinds of things they’re, er, metabolizing. They figure that there are at least 300 species living in the guts that they analyzed. It’s a whole ecosystem, and when it’s imbalanced, it could result in malnutrition, infections, obesity, and general crabbiness. But you’re never alone.
Gold started out with abiogenic petroleum, but after his conjecture, we keep finding enormous reservoirs of life throughout the earth and ourselves.