The Variables and Slow Transients Survey (VAST) on the Australian Square Kilometre Array Pathfinder (ASKAP) is designed to detect highly variable and transient radio sources on timescales from 5 s to $\sim\!5$ yr. In this paper, we present the survey description, observation strategy and initial results from the VAST Phase I Pilot Survey. This pilot survey consists of $\sim\!162$ h of observations conducted at a central frequency of 888 MHz between 2019 August and 2020 August, with a typical rms sensitivity of $0.24\ \mathrm{mJy\ beam}^{-1}$ and angular resolution of $12-20$ arcseconds. There are 113 fields, each of which was observed for 12 min integration time, with between 5 and 13 repeats, with cadences between 1 day and 8 months. The total area of the pilot survey footprint is 5 131 square degrees, covering six distinct regions of the sky. An initial search of two of these regions, totalling 1 646 square degrees, revealed 28 highly variable and/or transient sources. Seven of these are known pulsars, including the millisecond pulsar J2039–5617. Another seven are stars, four of which have no previously reported radio detection (SCR J0533–4257, LEHPM 2-783, UCAC3 89–412162 and 2MASS J22414436–6119311). Of the remaining 14 sources, two are active galactic nuclei, six are associated with galaxies and the other six have no multi-wavelength counterparts and are yet to be identified.

Scholarly interest has been growing in an episode of Old World globalisation of food resources significantly predating the ‘Silk Road’. This process was characteristic of crosscontinental translocations of starch-based crops mostly during the third and second millennia BC but which might have been initiated in an earlier period (Jones et al. 2011). Among these translocations we can include a range of crops originally from Southwest Asia, notably bread wheat and barley, and others originally from northern China, such as broomcorn and foxtail millet (Hunt et al. 2008; Motuzaite-Matuzeviciute et al. 2013). Parallel patterns of crop movement between North Africa and South Asia have been observed and discussed in some depth (Boivin & Fuller 2009; Fuller et al. 2011; Boivin et al. 2013). The impetus behind this growth of interest has been the expansion of archaeobotanical research in South and East Asia over the past decade (Fuller 2002; Crawford 2006; Lee et al. 2007; Liu et al. 2008; Zhao 2010). This paper considers the agents responsible for the food globalisation process during the third and second millennia BC. A key aspect of trans-Eurasian starch-crop movement was that it constituted an addition to agricultural systems, rather than movement to regions devoid of existing starch-based agriculture. Other economic plants, such as grapes, dates and peas, also moved considerable distances in the archaeological record, often to areas previously devoid of those plants. However, the novel starchy crops held a particular significance. In both cases, Southwest Asian wheat and barley and East Asian millets went on to become important staple foods in many of their new destinations.

The classic image of Upper Palaeolithic hunter-gatherers in Europe envisages them hunting large mammals in largely treeless landscapes. That is partly due to the nature of the surviving archaeological evidence, and the poor preservation of plant remains at such ancient sites. As this study illustrates, however, the potential of Upper Palaeolithic sites to yield macrofossil remains of plants gathered and processed by human groups has been underestimated. Large scale flotation of charred deposits from hearths such as that reported here at Dolní Vӗstonice II not only provides insight into the variety of flora that may have been locally available, but also suggests that some of it was being processed and consumed as food. The ability to exploit plant foods may have been a vital component in the successful colonisation of these cold European habitats.

The majority of the early crops grown in Europe had their origins in south-west Asia, and were part of a package of domestic plants and animals that were introduced by the first farmers. Broomcorn millet, however, offers a very different narrative, being domesticated first in China, but present in Eastern Europe apparently as early as the sixth millennium BC. Might this be evidence of long-distance contact between east and west, long before there is any other evidence for such connections? Or is the existing chronology faulty in some way? To resolve that question, 10 grains of broomcorn millet were directly dated by AMS, taking advantage of the increasing ability to date smaller and smaller samples. These showed that the millet grains were significantly younger than the contexts in which they had been found, and that the hypothesis of an early transmission of the crop from east to west could not be sustained. The importance of direct dating of crop remains such as these is underlined.

Francesco Guala has developed some novel and radical ideas on the problem of external validity, a topic that has not received much attention in the experimental economics literature. In this paper I argue that his views on external validity are not justified and the conclusions which he draws from these views, if widely adopted, could substantially undermine the experimental economics enterprise. In rejecting the justification of these views, the paper reaffirms the importance of experiments in economics.