Pumice is rock that is ejected from a volcano, and has so much gas trapped in it that it can float. So when a pumice-ejecting volcano (not all volcanoes produce pumice) goes off near a body of water, you can get a raft of rock floating around for quite some time. By and by, water replaces the gas within the rock and it sinks. Like a rock. So, you can get layers of pumice on the bed of lakes, seas and oceans. A forthcoming paper in Deep Sea Research I describes two such pumice deposits of “Drift Pumice” in the Indian Ocean. Continue reading Deep Sea Evidence of Major Volcanic Eruptions
Homo floresiensis more widely known as the “Hobbit,” may have had arms that were very different from those of modern humans.
A paper in the current issue of the Journal of Human Evolution explores the anatomy of H. floresiensis. To explore this we first have to understand the concept of “Humeral torsion.” Humeral torsion is the orientation of the humeral head relative to the mediolateral axis of the distal articular surface. Don’t bother reading that sentence again, I’ll explain it.
Every few years a paper comes out “explaining” short stature in one or more Pygmy groups. Most of the time the new work ads new information and new ideas but fails to be convincing. This is the case with the recent PNAS paper by Migliano et al.
From the abstract:
There seems to be some interesting things going on with the recently reported study of rates of evolution in humans. We are getting reports of a wide range of rather startling conclusions being touted by the researchers who wrote this paper. These conclusions typically come from press releases, and then are regurgitated by press outlets, then read and reported by bloggers, and so on. Here is, in toto, the press release from the University of Wisconsin, where John Hawks, one of the authors of the study, works. I reproduce the press release here without further comment. Continue reading Human Evolutionary Rate Study