Enough Oxygen for Life Found Millions of Years Too Early. Earth’s atmosphere contained enough oxygen for complex life to develop nearly 1.2 billion years ago — 400 million years earlier than scientists previously believed.
The findings, reported in the Nov. 11 Nature, could lead scientists to reconsider the prerequisites for animal life, on Earth and other planets. “It means that the conditions were in place for complex life to arise,” said geologist John Parnell of the University of Aberdeen in Scotland, lead author of the new study. “There might be animals in that earlier window that we have not yet found.” Geological records show there was one major increase in the amount of oxygen in Earth’s atmosphere around 2.3 billion years ago, and another around 800 million years ago.
That second spike in oxygen levels was thought to be connected to the Cambrian explosion, the swift development of most of the major animal groups that came around 550 million years ago. Natural selection and unneeded traits « Say what, Michael Pollan? I wanted to be moving on to writing about Pollan’s hunting trip today, but yesterday my mind wandered back to a line from the section about animal happiness that I decided I just couldn’t leave without comment.
In his discussion of domestication Pollan writes, Both parties were transformed by the new relationship: The animals grew tame and lost their ability to fend for themselves in the wild (natural selection tends to dispense with unneeded traits) and the humans traded their hunter-gatherer ways for the settled lives of agriculturists. (320) My interest here is in that parenthetical comment, “natural selection tends to dispense with unneeded traits.” It’s a statement that anybody who has ever had appendicitis might take issue with.
Does Darwin’s theory hold up? NYU (US) — Charles Darwin’s theory of gradual evolution is not supported by geological history, according to a new paper.
That theory, put forth by Scottish horticulturalist Patrick Matthew prior to Darwin’s published work, claims long periods of evolutionary stability disrupted by catastrophic mass extinctions of life, is a far more likely a scenario, says Michael Rampino, a geologist at New York University. “Matthew discovered and clearly stated the idea of natural selection, applied it to the origin of species, and placed it in the context of a geologic record marked by catastrophic mass extinctions followed by relatively rapid adaptations,” says Rampino, whose research on catastrophic events includes studies on volcano eruptions and asteroid impacts.
Rampino’s theory is published in the journal Historical Biology.