Pattern of extinction of the woolly mammoth in Beringia

Extinction of the woolly mammoth in Beringia has long been subject to research and speculation. Here we use a new geo-referenced database of radiocarbon-dated evidence to show that mammoths were abundant in the open-habitat of Marine Isotope Stage 3 (∼45–30 ka). During the Last Glacial Maximum (∼25–20 ka), northern populations declined while those in interior Siberia increased. Northern mammoths increased after the glacial maximum, but declined at and after the Younger Dryas (∼12.9–11.5 ka). Remaining continental mammoths, now concentrated in the north, disappeared in the early Holocene with development of extensive peatlands, wet tundra, birch shrubland and coniferous forest. Long sympatry in Siberia suggests that humans may be best seen as a synergistic cofactor in that extirpation. The extinction of island populations occurred at ∼4 ka. Mammoth extinction was not due to a single cause, but followed a long trajectory in concert with changes in climate, habitat and human presence

Localization and loss of coherence in molecular double-slit experiments

In molecular double-slit experiments, the interference between emitted core electrons of diatomic molecules gives rise to oscillations in the observed electron intensity. Here, we explore this behaviour for photoelectrons emitted from CO and N_2 by soft X-ray ionization in the molecular frame, and we argue that in addition to the undisturbed emission process, intramolecular scattering can lead to electron interference between the scattered and unscattered wave in two ways: two-centre interference between two spatially coherent emitters and one-centre self-interference. The latter is the signature of a loss of spatial coherence. The spatial scale over which the transition from two-centre to one-centre coherence occurs is the de Broglie wavelength of the scattered photoelectron in units of the bond length. These results highlight the fact that the molecular double slit is based on two independent uncertainty principles, Δp_xΔx and ΔEΔt, the second of which causes ongoing tunnelling between the two centres, even after the collapse of the electron wavefunction in real space