As zoos’ goals, designers’ values, and guests’ expectations change, so do the structures seen at the zoo. Exhibit history is not clear cut, and – despite what some may claim – is not inherently linear. Exhibit strategies develop as a result of tensions, both social and operational, imposed from both inside and outside of zoos. This literature review examines the history of zoo architecture by defining six design periods and considering the lenses of race, class, and nature.

George McDonald Church studied DNA from living and from extinct species in the US during the twentieth and twenty-first centuries. Church helped to develop and refine techniques with which to describe the complete sequence of all the DNA nucleotides in an organism's genome, techniques such as multiplex sequencing, polony sequencing, and nanopore sequencing. Church also contributed to the Human Genome Project, and in 2005 he helped start a company, the Personal Genome Project. Church proposed to use DNA from extinct species to clone and breed new organisms from those species.