ReviewsREVIEW

The interaction of human population, food production, and biodiversity protection

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Science  21 Apr 2017:
Vol. 356, Issue 6335, pp. 260-264
DOI: 10.1126/science.aal2011

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  • RE: Cities and Conservation
    • Eric W. Sanderson, Senior Conservation Ecologist, Wildlife Conservation Society
    • Other Contributors:
      • John G. Robinson, Executive Senior Vice President, Wildlife Conservation Society
      • Joe Walston, Vice President, Wildlife Conservation Society

    Crist et al. (Science 356, 260–264 (2017)) note that concerns with population growth have fallen off the global conservation agenda, but underplay the most the most important factor leading toward population stabilization and possible future conservation gains: urbanization. Urbanization is the growth in the proportion of the population that lives in densely occupied, built-up areas rather than rural ones. Urbanization affects population size through its influence on fertility; urban people have fewer kids because modern towns and cities create both carrots and sticks when it comes to family size [1]. As Crist et al. point out, family planning and women’s empowerment are critical to the number of children a woman chooses to have; both are more available in cities. Urban life also provides economic disincentives to large families, through the cost of rent, travel and food, while cities provide better returns on education through more diverse, better paid employment opportunities [2]. Urban lifestyles appear to be more resource-efficient and less polluting on a per-capita basis than rural ones, when controlling for wealth [3]. The combined effect of these factors is that long-term projections of population, such as the shared socioeconomic pathways [SSPs; 4], suggest that a world that actively promotes liveable cities could lead to an earlier peak in population (by 2065) and a lower overall population (6.4 billion, per SSP1 in [4]), than more laissez-faire policies th...

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    Competing Interests: None declared.
  • RE: Cities and conservation
    • Eric W. Sanderson, Senior conservation ecologist, Wildlife Conservation Society
    • Other Contributors:
      • John G. Robinson, Executive Senior Vice President, Wildlife Conservation Society

    Crist et al. (Science 356, 260–264 (2017)) note that concerns with population growth have fallen off the global conservation agenda, but underplay the most the most important factor leading toward population stabilization and possible future global conservation gains: urbanization. Urbanization is the growth in the proportion of the population that lives in densely occupied, built-up areas rather than rural ones. Urbanization affects population size through its influence on fertility; urban people have fewer kids because modern towns and cities create both carrots and sticks when it comes to family size (1). As Crist et al. point out, family planning and women’s empowerment are critical to the number of children a woman chooses to have; both are more available in cities. Urban life also provides economic disincentives to large families, through the cost of rent, travel and food, while cities provide better returns on education through more diverse, better paid employment opportunities (2). Urban lifestyles appear to be more resource-efficient and less polluting on a per-capita basis than rural ones, when controlling for wealth (3). The combined effect of these factors is that long-term projections of population, such as the shared socioeconomic pathways (SSPs; 4), suggest that a world that actively promotes liveable cities could lead to an earlier peak in population (by 2065) and a lower overall population (6.4 billion, per SSP1 in (4)), than more laissez-faire poli...

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    Competing Interests: None declared.
  • RE: Monogamy helps to increase inner-biodiversity but slowdown the evolution speed
    • Cedric Fan, Professor, MIT Information Quality Program- Data Quality & Info Security Lab, Nanjing Tech University

    In their REVIEW “The interaction of human population, food production, and biodiversity protection” (Science 21 April 2017: Vol. 356 no. 6335 pp. 260-264), Eileen Crist et al. (1) described an approach to sustain biodiversity and human well-being through several actions that can slow and eventually reverse population growth.

    Their finding is quite interesting and useful and can affect both inner-biodiversity and outer-biodiversity. To only discover the inner-biodiversity itself, we use SREA (Sexual Reproductive Evolution Algorithm) to analyse the relation of inner-biodiversity and evolution speed. We find that Monogamy slows down the evolution speed, however it helps to increase inner-biodiversity and avoid early mature. Furthermore, some useful indexes can also be deduced with SREA, which can be used to regulate the evolution speed and inner-biodiversity.

    REFERENCES
    1 Eileen Crist et al. , Science 356, 6335 (2017).
    2 National Natural Science Foundation of China (71671089, 71171110)

    Competing Interests: None declared.
  • Part of the interactive solution

    In their review, Crist, Mora, and Engelman are right to call attention to the role of total human population in total human impact, and their calls for greater access by women to health and education are welcome on many grounds. I was disappointed, however, to not see how reducing global human population would INTERACT with other changes in lessening total human impact. A world that peaks in population at nine billion would have more options for sustainability than one that contains ten billion or more people. Adding a billion cows and a billion cars in the coming decades will negate most of these options. The slogan of “a chicken in every pot and a car in every garage” was dubious for Americans in 1928. It is dangerous for projecting the world of a century later. Thus any efforts to substantially reduce human impacts worldwide must address per capita resource consumption.

    Competing Interests: None declared.