编译| 李言
Science, 07 MAY 2021, VOL 372, ISSUE 6542
《科学》2021年5月7日，第372卷，6542期
古人类学Paleoanthropology
Unearthing Neanderthal population history using nuclear and mitochondrial DNA from cave sediments
利用洞穴Nuclear and mitochondrial DNA mining in sediments Population history of Neanderthal
▲ Authors: Benjamin Vernot, Elena I. Zavala, Asier Gómez-Olivencia, Zenobia Jacobs, et al.
▲ Link :
https: //science.sciencemag.org/content/372/6542/eabf1667
▲ Summary
Bone and teeth are important sources of Pleistocene human DNA, but are rarely found in archaeological sites. Mitochondrial DNA (mtDNA) can be extracted from cave sediments, but their value for studying population relationships is limited.
We therefore developed methods for collecting and analyzing nuclear DNA in sediments and applying them to cave sediments from 200,000 to 50,000 years ago.
We found a population turnover with mtDNA turnover in northern Spain about 100,000 years ago. We also identify two radiative evolutionary events in Neanderthals during the early Late Pleistocene. Our work lays the groundwork for studying the population history of hominins from trace amounts of nuclear DNA in sediments.
▲ Abstract
Bones and teeth are important sources of Pleistocene hominin DNA, but are rarely recovered at archaeological sites. Mitochondrial DNA (mtDNA) has been retrieved from cave sediments but provides limited value for studying population relationships. We therefore developed methods for the enrichment and analysis of nuclear DNA from sediments and applied them to cave deposits in western Europe and southern Siberia dated to between 200,000 and 50,000 years aGO. We detected a population replacement in northern Spain about 100,000 years ago, which was accompanied by a turnover of mtDNA. We also identified two radiation events in Neanderthal history during the early part of the Late Pleistocene. Our work lays the ground for studying the population history of ancient hominins from trace amounts of nuclear DNA in sediments.
PaleobiologyPaleobiology
Evolution of vision and hearing modalities in theropod dinosaurs
兽脚类恐龙视觉和听觉模式的进化
▲ 作者：Jonah N. Choiniere, James M. Neenan, Lars Schmitz, David P. Ford, et al.
▲ 链接：
https ://science.sciencemag.org/content/372/6542/610
▲ Abstract
Owls and nightingales are nocturnal predators that combine visual and auditory changes to overcome sensory performance in low light limits.Such sensory alterations are not found in theropods of non- birds, , and are rarely identified in lineages that evolved toward birds.
We study morphofunctional proxies for vision and hearing in extant and -extinct theropods and demonstrate a deep evolutionary divergence in sensory modalities. Nocturnal -predation evolved early in the non-avian avarazosaurs, manifesting as extremely weak vision and increased hearing sensitivity.
The desert bird-faced dragon of the late Cretaceous period had a more special hearing, comparable to that of today's barn owl. This combination of sensory adaptations evolved independently in dinosaurs long before the advent of radiation evolution in modern birds, and provides a striking example of the fusion of dinosaurs and mammals.
▲ Abstract
Owls and nightbirds are nocturnal hunters of active prey that combine visual and hearing adaptations to overcome limits on sensory performance in low light. Such sensory innovations are unknown in nonavialan theropod dinosaurs and are poorly characterized on the line that leads to birds. We investigate morphofunctional proxies of vision and hearing in living and extinct theropods and demonstrate deep evolutionary divergences of sensory modalities. Nocturnal predation evolved early in the nonavialan lineage Alvarezsauroidea, signaled by extreme low-light vision and increases in hearing sensitivity. The Late Cretaceous alvarezsauroid Shuvuuia deserti had even further specialized hearing acuity, rivalry that of today's barn owl. This combination of sensory adaptations evolved independently in dinosaurs long before the modern bird radiation and provides a notable example of convergence between dinosaurs and ma mmals.
Materials ScienceMaterials Science
Reversible fusion and fission of graphene oxide–based fibers
Reversible fusion and splitting of graphene oxide fibers
▲ Author: Dan Chang, Jingran Liu, html Fang, html , Zhen50, et al.
https://science.sciencemag.org/content/372/6542/614
▲ Abstract
Stimulus-response fusion and fragmentation is widely observed in biological tissues and artificial molecular assemblies.However, it remains challenging to design a system with durable structure and performance in the repeated process of fusion and splitting.
We investigated the reversible fusion and splitting of graphene oxide (GO) fibers, and many macroscopic fibers can be fused into thicker fibers or separated into pristine individual fibers under the stimulation of solvent .
The dynamic geometric deformation of the graphene oxide fiber shell caused by solvent evaporation and infiltration is the key to realizing the reversible fusion-fission cycle. This principle is extended to enable flexible transitions between complex fiber assemblies and the inclusion or expulsion of guest compounds.
▲ Abstract
Stimuli-responsive fusion and fission are widely observed in both bio-organizations and artificial molecular assemblies. However, the design of a system with structure and property persistence during repeated fusion and fission remains challenging. We show reversible fusion and fission of wet- spun graphene oxide (GO) fibers, in which a number of macroscopic fibers can fuse into a thicker one and can also separate into original individual fibers under stimulation of solvents. The dynamic geometrical deformation of GO fiber shells, caused by solvent evaporation and infiltration, is the key to the reversible fusion-fission cycles. This principle is extended to implement flexible transitions between complex fiber assemblies and the inclusion or expulsion of guest compounds.
Quantum PhysicsQuantum Physics
Direct observation of dete rministic macroscopic entanglement
Macroscopic objectsDirect evidence for quantum entanglement
▲ Authors: Shlomi Kotler, Gabriel A. Peterson, Ezad Shojaee, Florent Lecocq, et al.
21▲ Links: html.
orghtml/science1html /6542/622
▲ Abstract
Quantum entanglement of mechanical systems occurs when different objects move, and the correlations between them are so high that they cannot be described individually.
While quantum mechanics may be applicable to objects of all sizes, direct observation of entangled becomes challenging as mass increases, requiring measurement and control with minimal error.
Here, using pulsed electricity, we definitively entangle two mechanical drumheads with a mass of 70 micrograms. By measuring the position and momentum integrals of the two drums at the near-quantum limit, we performed quantum state tomography to directly observe entanglement.
This entangled macroscopic system will function in fundamental tests of quantum mechanics, enabling perception beyond the standard quantum limit, and functioning as a long-term network node for the future quantum network .
▲ Abstract
Quantum entanglement of mechanical systems emerges when distinct objects move with such a high degree of correlation that they can no longer be described separately. Although quantum mechanics presumably applies to objects of all sizes, directly observing entanglement becomes challenging as masses increase, requiring measurement and control with a vanishingly small error. Here, using pulsed electromechanics, we deterministically entangle two mechanical drumheads with masses of 70 picograms. Through nearly quantum-limited measurements of the position and momentum quadratures of both drums, we perform quantum state tomography and thereby directly observe entanglement. Such entangled macroscopic systems are poised to serve in fundamental tests of quantum mechanics, enable sensing beyond the standard quantum limit, and function as long-lived nodes of future quantum networks.
Quantum mechanics–free subsystem with mechanical oscillators
Quantum-free subsystem with mechanical oscillators
▲ By Laure Mercier de Lépinay, Caspar F. Ockeloen-Korppi, Matthew J. Woolley, Mika A. Sillanpää
1
▲Link:
▲ /science.sciencemag.org/content/372/6542/625
▲ Abstract
Quantum mechanics sets a limit for the accuracy of continuously measuring oscillator position. We show how to measure an oscillator without measuring quantum reaction by constructing an efficient oscillator.
We implemented such a subsystem that does not involve quantum mechanics using two micromechanical oscillators, and displayed the results of two collective quadrature measurements, while avoiding the 8 dB quantum reaction for both of them, obtaining a Total noise within 2 times the full quantum limit.
This facilitates the detection of weak forces and the generation and measurement of non-classical motion states of oscillators. Furthermore, we directly verify the quantum entanglement of the two oscillators by measuring the amount of segments at 1.4 dB below the separability bound.
▲ Abstract
Quantum mechanics sets a limit for the precision of continuous measurement of the position of an oscillator. We show how it is possible to measure an oscillator without quantum back-action of the measurement by constructing one effective oscillator from two physical oscillators. We realize such a quantum mechanics–free subsystem using two micromechanical oscillators, and show the measurements of two collective quadratures while evading the quantum back-action by 8 decibels on both of them, obtaining a total noise within a factor of 2 of the full quantum limit. This facilitates the detection of weak forces and the generation and measurement of nonclassical motional states of the oscillators. Moreover, we directly verify the quantum entanglement of the two oscillators by measuring the Duan quantity 1.4 decibels below the separability bound.
zoologyZoology
Extreme altitudes during diurnal flights in a nocturnal songbird migrant
夜间鸣禽候鸟在日间飞行时的极端高度
▲ 作者：Sissel Sjöberg, Gintaras Malmiga, Andreas Nord, Arne Andersson, et al.
▲ 链接：
https:// science.sciencemag.org/content/372/6542/646
▲ Abstract
Billions of nocturnal migratory songbirds fly over oceans and deserts every year.Using multi-sensor data loggers, we found that great reed warblers (Acrocephalus arundinaceus) regularly extend their nighttime flight into daytime as they traverse the Mediterranean and Sahara deserts.
Unexpectedly, when the flight time was extended, they climbed abruptly at dawn, from average altitude 2394m to extreme altitudes for daytime flight (average altitude 5367m, maximum altitude 6267m).
This previously unknown behavior of using very high fly heights during daytime migrations may be caused by diurnal variations in ambient temperature, wind, predation, field of view, and solar radiation. Our discovery of this behavior sheds new light on bird flight restriction and may help explain the evolution of nocturnal migration.
▲ Abstract
Billions of nocturnally migrating songbirds fly across oceans and deserts on their annual journeys. Using multisensor data loggers, we show that great reed warblers (Acrocephalus arundinaceus) regularly prolong their otherwise strictly nocturnal flights into daytime when crossing the Mediterranean Sea and the Sahara Desert . Unexpectedly, when prolonging their flights, they climbed steeply at dawn, from a mean of 2394 meters above sea level to reach extreme cruising altitudes (mean 5367 and maximum 6267 meters above sea level) during daytime flights. This previously unknown behavior of using exceedingly high flight altitudes when migrating during daytime could be caused by diel variation in ambient temperature, winds, predation, vision range, and solar radiation. Our finding of this notable behavior provides new perspectives on constraints in bird flight and might help to explain the evolution of nocturnal m igration.
