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Kramer, Karen L.

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Karen L.

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Kramer, Karen L.

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Author's Publications: search.filters.isAuthorOfPublication.7bde88b6-046c-4ed7-89b5-cdb28277e371

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    Energy Pooling and Implications for the Unique Traits of the Human Life History Strategy
    (John Wiley & Sons, 2009) Sharrock, Katherine C.; Reiches, Meredith W.; Lipson, Susan F.; Kramer, Karen L.; Ellison, Peter
    Compared to non-human primates, human life history is characterized by slow juvenile growth, late age at maturity, short interbirth intervals, and a decoupling of reproductive senescence and somatic senescence. Some of these traits represent a delay of reproductive effort while others represent an acceleration. To address this puzzle, we propose that humans in all three stages of the life span, pre-reproductives, adults of reproductive age, and post-reproductives, all contribute to a “pooled energy budget” (PEB) that is primarily utilized by the reproductively active female to carry out the energetically expensive tasks of gestation and lactation. Adults contribute to the pooled energy budget by providing food and care to children, thus freeing up the mother to provide more resources to a gestating fetus or a nursing infant and to resume postpartum ovulation more quickly. Pre-reproductives also contribute to the PEB. Older children, through participating in childcare and subsistence activities, can provide resources to partially meet their own energetic needs and to care for and provision younger siblings. The mother becomes the “final common pathway” through which energy flows in order to produce new offspring. While life history theory has traditionally considered growth, maintenance, and reproduction as the three main categories of energetic tradeoffs, we propose that energy allocated towards reproduction can be broken into two categories: direct and indirect reproductive effort. The contributions to the PEB made by both pre-reproductives and post-reproductives can be seen as indirect reproductive effort and can provide an explanation for slow childhood growth rates and menopause.
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    The Role of Demography and Markets in Determining Deforestation Rates Near Ranomafana National Park, Madagascar
    (Public Library of Science, 2009) Brooks, Christopher P.; Holmes, Christopher; Kramer, Karen L.; Barnett, Barry; Keitt, Timothy H.
    The highland forests of Madagascar are home to some of the world's most unique and diverse flora and fauna and to some of its poorest people. This juxtaposition of poverty and biodiversity is continually reinforced by rapid population growth, which results in increasing pressure on the remaining forest habitat in the highland region, and the biodiversity therein. Here we derive a mathematical expression for the subsistence of households to assess the role of markets and household demography on deforestation near Ranomafana National Park. In villages closest to urban rice markets, households were likely to clear less land than our model predicted, presumably because they were purchasing food at market. This effect was offset by the large number of migrant households who cleared significantly more land between 1989–2003 than did residents throughout the region. Deforestation by migrant households typically occurred after a mean time lag of 9 years. Analyses suggest that while local conservation efforts in Madagascar have been successful at reducing the footprint of individual households, large-scale conservation must rely on policies that can reduce the establishment of new households in remaining forested areas.