Taxonomy term

Residual organic carbon from dead marine phytoplankton and other oceanic life can follow two pathways: It can be deeply buried in seafloor sediments or it can be oxidized, either in the water column or in shallow sediment layers. The balance between these two processes and the extent of organic carbon burial over time are crucial in the global carbon cycle, but a complete understanding of the factors and rates controlling organic carbon burial versus oxidation in the oceans has been lacking. In a recent study in Geology, scientists improved on an approach to quantify organic carbon oxidation and provided a glimpse of marine organic carbon burial in the Precambrian, when the oceans were anoxic and Earth’s atmosphere was in the early stages of oxygenation.

 

Compared to chimpanzees, our recent evolutionary cousins, humans have long thumbs relative to our fingers. This trait has endowed our ancestors and us with a particular talent for grasping and working with tools, which likely contributed to our evolutionary success over the last several million years since splitting off from the last common ancestor (LCA) shared by the two groups. But rather than humans having the more evolved hand — a prevailing hypothesis since the late 20th century — a new study suggests that chimps’ hands, with lower thumb-to-finger-length ratios, have changed considerably more.