Measurement of low energy charge correlations in underdoped spin-glass La-based cuprates using impedance spectroscopy

We report on the charge kinetics of La_2CuO_4 lightly doped with Li and Sr. Impedance spectroscopy measurements down to 25mK and from 20Hz to 500kHz reveal evidence for low energy charge dynamics, which slow down with decreasing temperature. Both systems are acutely sensitive to stoichiometry. In the case of Sr substitution, which at higher carrier concentration evolves to a high temperature superconductor, the ground state in the pseudogap-doping regime is one of spatially segregated, dynamic charge domains. The charge carriers slow down at substantially lower temperatures than their spin counterparts and the dynamics are particularly sensitive to crystallographic direction. This is contrasted with the case of Li-doping.Comment: 4 pages, 4 figure

New Caledonian crows rapidly solve a collaborative problem without cooperative cognition

There is growing comparative evidence that the cognitive bases of cooperation are not unique to humans. However, the selective pressures that lead to the evolution of these mechanisms remain unclear. Here we show that while tool-making New Caledonian crows can produce collaborative behavior, they do not understand the causality of cooperation nor show sensitivity to inequity. Instead, the collaborative behavior produced appears to have been underpinned by the transfer of prior experience. These results suggest that a number of possible selective pressures, including tool manufacture and mobbing behaviours, have not led to the evolution of cooperative cognition in this species. They show that causal cognition can evolve in a domain specific manner-understanding the properties and flexible uses of physical tools does not necessarily enable animals to grasp that a conspecific can be used as a social tool

Technology led to more abstract causal reasoning

Many animal species use tools, but human technical engagement is more complex. We argue that there is coevolution between technical engagement (the manufacturing and use of tools) and advanced forms of causal cognition in the human (Homo) lineage. As an analytic tool, we present a classification of different forms of causal thinking. Human causal thinking has become detached from space and time, so that instead of just reacting to perceptual input, our minds can simulate actions and forces and their causal consequences. Our main thesis is that, unlike the situation for other primate species, an increasing emphasis on technical engagement made some hominins capable of reasoning about the forces involved in causal processes. This thesis is supported in three ways: (1) We compare the casual thinking about forces of hominins with that of other primates. (2) We analyze the causal thinking required for Stone Age hunting technologies such as throwing spears, bow hunting and the use of poisoned arrows, arguing that they may serve as examples of the expansion of casual cognition about forces. (3) We present neurophysiological results that indicate the facilitation of advanced causal thinking