Megafaunal extinction in the late Quaternary and the global overkill hypothesis

The global blitzkrieg hypothesis explains differential rates of megafaunal extinction between the world's landmasses in the late Quaternary based on a proposed leap in predation efficiency enjoyed by colonising societies. It is characterised by appealing simplicity. Selective over hunting, facilitated by naiveté to human predation, produced rapid mass extinctions of large animals wherever subsistence societies colonised new landmasses. Taken at face value the circumstantial case for blitzkrieg is compelling and despite a paucity of direct evidence it has gained considerable support. Our review of the model suggests that it overlooks much contradictory data and rests on simplistic interpretations of complex biogeographicat and anthropological phenomena. These interpretations and assumptions do not account for major differences between the biotas, ecologies and human cultures of the landmasses involved. The assertion that responses of remote island species to human predation provide realistic models for those of continental taxa is poorly founded, exaggerating the likely predation efficiency of humans colonising continents. An absence of terrestrial predators over evolutionarily significant periods, together with restricted ranges and small populations, renders island faunas uniquely vulnerable to invaders. The argument, that climate cannot explain these phenomena because previous Glacial Maxima did not cause comparable extinctions, presupposes that their local effects were at least as severe as those of the Last Glacial Maximum. This has yet to be demonstrated and at most it would indirectly support a role for anthropogenic influence, not overkill per se. Overlooked or underplayed are the influences of translocated and other invading species. Similarly, differences in the origins, technologies and traditions of colonising human societies are rarely considered. These factors strongly impact on the predation efficiency, density and range of human populations, critically affecting the outcomes of predator-prey modeling. When a fuller constellation of influences and constraints is considered it is reasonable to posit that rapid mass extinction through selective human predation may largely describe megafaunal extinctions on remote islands, but the argument is not convincing for continents. This is especially so regarding Australia. Because even the largest Australian species were prey to endemic carnivores, their responses to human predation would not have been comparable to those of oceanic island species. No kill-sites or specialized big-game hunting/butchering tools are known and, on the basis of ethnographic and archaeological data, it is probable that predation efficiency, population density and range of the first Australians were insufficient to effect rapid mass extinction. Chronologies of human arrival and the disappearance of megafauna remain poor, but the most recent estimates for human-megafaunal coexistence in Australia range from 10,000 to 43,000 years. Although human predation may have been a contributing factor in megafaunal extinctions, rapid overkill is unlikely to describe the actual mechanism in most instances. The role of human predation and its significance relative to competing factors, human and otherwise, varied considerably between landmasses, as did the speeds with which extinctions occurred. Blitzkrieg and other mono-factorial models are heuristically valuable devices, but a growing body of evidence suggests that extinction can rarely, if ever, be attributed to a single cause.     

Dealing with Sustainability Trade-Offs of the Compact City in Peri-Urban Planning Across European City Regions

The compact city has become a leading concept in the planning of peri-urban areas. The compact city concept is often advocated as “sustainable” because of claims that include lower emissions and conservation of the countryside. The literature shows, however, that there are certain trade-offs in striving for compaction, especially between environmental and social aspects of sustainability. In this article, we describe expressions of the compact city concept in the planning practice of several European urban sample regions, as well as policies and developments that contradict the compact city. We look at examples of positive and negative impacts of the compact city that were observed in the sample regions. Further, we discuss attempts by planners to deal with sustainability trade-offs. Being aware that developments in the peri-urban areas are closely connected to those in the inner city, we compare the sample regions in order to learn how the compact city concept has been used in planning peri-urban areas across different contexts in Europe: in Western, Central and Mediterranean Europe, and with growing, stable or declining populations. We conclude with recommendations with respect to balance in applying the compact city concept.     

Voices of Rotuma: Enduring Refrain

ABSTRACT

Polynesian Rotuma was blessed by its large coconuts and became an early focus for foreigners seeking trade in coconut oil and copra. Once the island became part of British Fiji in 1881, Rotumans voiced their concerns about increased shipping costs when going via Fiji as the port of entry. From the early 20th century they had visions of owning their own ship and thus greater control over prices for exported copra and imported goods. This article seeks to examine their constant efforts to make traders deal more fairly while seeking to manage their own shipping. Though they had some success, particularly when they formed a cooperative after World War Two, their goal largely proved unattainable but the vision and the voices have endured.     

Innovation,knowledge and relations – on the role of clusters for firms’ innovativeness

ABSTRACT

For more than two decades, theories on regional clusters have inspired economic and structural policies at the European, national and regional levels. Based on the assumption that clusters generate innovation, policy-makers at all levels of governance have adopted instruments and mechanisms to stimulate, resource and sustain clusters. Despite the considerable attention paid to the clustering phenomenon, empirical evidence on to what extent firms’ innovation activities benefit from operating in clusters is scarce and inconclusive. This paper contributes to the micro-foundation of clustering effects by examining the characteristics and activities of cluster firms in relation to their innovativeness. Bridging innovation, management and cluster theories, it is argued that structural and relational embeddedness, relational capital and absorptive capacity influence clustered firms' innovativeness. Partial least-squares structural equation modelling of data from 104 firms in two software and information technology service sector clusters reveals that firms’ structural embeddedness (i.e. frequency of interactions) in clusters and external networks facilitates innovation cooperation. Firms’ absorptive capacity reinforces this positive effect of cluster-internal interactions on innovation cooperation. Results also suggest a substitution effect of trust as relational control mechanisms for formal control mechanisms within the cluster. However, the study finds no significant impact of firms’ innovation cooperation within the cluster (i.e. relational embeddedness) on their innovation success.