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D. Jablonski [Proc. Natl. Acad. Sci. U.S.A. 99, 8139-8144 (2002)] coined the term "dead clades walking" (DCWs) to describe marine fossil orders that experience significant drops in genus richness during mass extinction events and never rediversify to previous levels. This phenomenon is generally interpreted as further evidence that the macroevolutionary consequences of mass extinctions can continue well past the formal boundary. It is unclear, however, exactly how long DCWs are expected to persist after extinction events and to what degree they impact broader trends in Phanerozoic biodiversity. Here we analyze the fossil occurrences of 134 skeletonized marine invertebrate orders in the Paleobiology Database (paleobiodb.org) using a Bayesian method to identify significant change points in genus richness. Our analysis identifies 70 orders that experience major diversity losses without recovery. Most of these taxa, however, do not fit the popular conception of DCWs as clades that narrowly survive a mass extinction event and linger for only a few stages before succumbing to extinction. The median postdrop duration of these DCW orders is long (>30 Myr), suggesting that previous studies may have underestimated the long-term taxonomic impact of mass extinction events. More importantly, many drops in diversity without recovery are not associated with mass extinction events and occur during background extinction stages. The prevalence of DCW orders throughout both mass and background extinction intervals and across phyla (>50% of all marine invertebrate orders) suggests that the DCW pattern is a major component of macroevolutionary turnover.

The objective of this formative research was to explore the acceptability and feasibility of changing housekeeping behaviors as a low-cost approach that may reduce childhood lead exposure in Johannesburg, South Africa. Using the Trials of Improved Practices (TIPs) methodology, modified housekeeping behaviors were negotiated with participants who chose the behaviors they wanted to try and then performed them in their homes over 4 weeks. Researchers interviewed them at the end of the month to understand their experience of trying out the behaviors. The modified behaviors offered to each participant were as follows: cleaning window sills with detergent and water, cleaning window sills more frequently, mopping floors with two buckets (one with soapy water for washing and one with clean water for rinsing), mopping floors more frequently, dusting surfaces with detergent and water and dusting surfaces more frequently. Participants found cleaning window sills with soap and water and cleaning them more often the most acceptable and feasible of behavior modifications. Environmental samples showed a significant reduction in lead dust on window sills. These findings can assist in the development of acceptable and feasible medium-term interventions to reduce childhood lead exposure in resource-poor settings until more robust health policies are implemented.

Indoor air pollution is responsible for the deaths and illness of millions of young children in developing countries. This study investigated the acceptability (willingness to try) and feasibility (ability to perform) of four indoor air pollution reduction behaviors (improve stove maintenance practices, child location practices, ventilation practices and reduce the duration of solid fuel burning). The study further aimed to identify the motivations for and barriers against modifying the behaviors, the perceived impact of the behaviors on children's respiratory health, and families intention to continue with the behaviors. Thirty families in a rural village of South Africa tried out one or more of the behaviors over a 4-week trial period during winter 2002. Improving stove maintenance and reducing the duration of solid fuel burning proved to be very difficult for most families. It is recommended that the main intervention should focus on improving child location and ventilation practices. (Contains 1 table.)