In southern Africa, Middle Stone Age sites with long sequences have been the focus of intense international and interdisciplinary research over the past decade (cf. Wadley 2015). Two techno-complexes of the Middle Stone Age—the Still Bay and Howiesons Poort—have been associated with many technological and behavioural innovations of Homo sapiens. The classic model argues that these two techno-complexes are temporally separated ‘horizons’ with homogenous material culture (Jacobs et al. 2008), reflecting demographic pulses and supporting large subcontinental networks. This model was developed on the basis of evidence from southern African sites regarded as centres of subcontinental developments.

Studies examining factors that influence when words are learned typically investigate one lexical category or a small set of words. We provide the first evaluation of the relation between input frequency and age of acquisition for a large sample of words. The MacArthur-Bates Communicative Development Inventory provides norming data on age of acquisition for 562 individual words collected from the parents of children aged 0 ; 8 to 2 ; 6. The CHILDES database provides estimates of frequency with which parents use these words with their children (age: 0 ; 7–7 ; 5; mean age: 36 months). For production, across all words higher parental frequency is associated with later acquisition. Within lexical categories, however, higher frequency is related to earlier acquisition. For comprehension, parental frequency correlates significantly with the age of acquisition only for common nouns. Frequency effects change with development. Thus, frequency impacts vocabulary acquisition in a complex interaction with category, modality and developmental stage.

Since at least the mid-1970s, public health and law enforcement officials have conducted joint or parallel investigations of both health problems possibly associated with criminal intent and crimes having particular health dimensions. However, the anthrax and other terrorist attacks of fall 2001 have dramatically underscored the needs that public health and law enforcement officials have for a clear understanding of the goals and methods each discipline uses in investigating such problems, including and especially the potential use of biologic agents as weapons of mass destruction. Recognition of these needs has prompted some experts to call for the application of “forensic epidemiology” to such problems. Even before the attacks of fall 2001, other problems, such as the detection of the West Nile Virus in the United States and concerns that the emergence of this infectious agent was the consequence of a deliberate act, raised novel challenges to the combined interests of public health and criminal investigators.

In a recent note, Marcus (1995) suggests that the rate of overregularization of English irregular plural nouns is not substantively different from that of English irregular past tense verbs. This finding is claimed to be in conflict with the predictions of connectionist models (Plunkett & Marchman, 1991, 1993) which are said to depend solely on the dominance of regular over irregular forms in determining overregulation errors. However, these conclusions may be premature given that Marcus averaged overregulation rates across irregular nominal forms that varied in token frequency and across samples representing a broad range of children's ages. A connectionist view would predict an interplay between type frequency and other item level factors, e.g. token frequency, as well as differences in the developmental trajectories of the acquisition of nouns and verbs. In this response, we briefly review longitudinal parental report data (N=26) which indicate that children are significantly more likely to produce noun overregularizations than verb overregularizations across a prescribed age period (1;5 to 2;6). At the same time, these data also show that children are familiar with proportionately more irregular nouns than irregular verbs. These findings are consistent with the predictions of Plunkett & Marchman (1991, 1993) in that the larger regular class affects the frequency of noun errors but also that familiarity with individual irregular nouns tends to reduce the likelihood of overregularizations. In contrast to the conclusion of Marcus (1995), the connectionist approach to English inflectional morphology provides a plausible explanation of the phenomenon of overregularization in both the English plural and past tense systems.

This study examines the Florentine economy and women's role in it from the fifteenth to the seventeenth centuries. The changes that took place in the Florentine economy as it adapted to new economic opportunities undermine the notion of economic decline and suggest instead considerable resilience. The changes that took place helped to produce and were themselves the product of the growing participation of women in the economy.