{102}Harry Harlow and Robert Zimmermann,'Affectional Responses in the Infant Monkey',Science 130:3373(1959),421-432;Harry Harlow,'The Nature of Love',American Psychologist 13(1958),673-685;Laurens D.Young et al.,'Early stress and later response to seprate in rhesus monkeys',American Journal of Psychiatry 130:4(1973),400-405;K.D.Broad,J.P.Curley and E.B.Keverne,'Mother-infant bonding and the evolution of mammalian social relationships',Philosophical Transactions of the Royal Soceity B 361:1476(2006),2199-2214;Florent Pittet et al.,'Effects of maternal experience on fearfulness and maternal behaviour in a precocial bird',Animal Behavior (March 2013),In Press-available online at:http://www.sciencedirect.com/science/article/pii/S0003347213000547)

{103}"National Institute of Food and Agriculture",United States Department of Agriculture,accessed December 10,2010,http://www.csrees.usda.gov/qlinks/extension.html.

{104}Vaclav Smil,The Earth's Biosphere:Evolution,Dynamics,and Change (Cambridge,Mass.:MIT Press,2002);Sarah Catherine Walpole et al.,'The Weight of Nations:An Estimation of Adult Human Biomass',BMC Public Health 12:439(2012),http://www.biomedcentral.com/1471-2458/12/439

{105}William T.Jackman,The Development of Transportation in Modern England (London:Frank Cass &co.,1966),324-27;H.J.Dyos and D.H.Aldcroft,British Transport-An economic survey from the seventeenth century to the twentieth (Leicester:Leicester University Press,1969),124-31;Wolfgang Schivelbusch,The Railway Journey:The Industrialization of Time and Space in the 19th Century (Berkeley:Univeristy of California Press,1986).