Illustrations are indicated with bold face
Advanced Cell Technology, 137–38, 142
Agenbroad, Larry, 86
Allee effect, 180
amber, DNA preserved in, 45, 51–54, 56–58, 60–61; laboratory process to collect, insert
ancient DNA: age and survival of, 65–66; amber as source of, 45, 51–54, 56– 58, 60–61; applications of, 10–11, 54–56; authentication of, 56–57, 60, 62, 69–70; co-extraction of environmental DNA, 42–43, 63–64, 70, 194; contamination with modern DNA, 56–63, 69, 194; degradation of, 60–61, 64–65; dinosaurs as sources of, 61; environmental conditions and preservation of, 64–65, 70–71; evolutionary processes revealed by, 10–11, 54–55; extraction of, 51–53, 65–66, 70; fossils as source of, 61, 63– 70, 113–14; fragmentary nature of, 41– 42, 60–61, 96, 113–14, 194; genome sequencing and assembly of, 10–11, 39–44, 56–58, 69–70, 111–15; preservation of, 54, 57, 64–66, 70–71, 83–84, 91; survival of authentic and very old, 66–71
animal welfare, 14, 152–53, 170–71, 172, 194–95
Archer, Mike, 190
autopsies, mammoth, 83–84, 90–91
back-breeding, 100–108, 130–31, 185
bears, 15, 26, 70, 167–68, 199
beavers: giant, 3; reintroduction to Great Britain, 200–201
behavior: as barrier to de-extinction, 31, 47, 172–73, 199; captive rearing and, 31, 47–48, 169–71, 176–79; captivity and, 146, 168–72, 179, 181, 183; environment and, 10–11, 100 (See also captivity and under this heading); genetic engineering and, ix–x, 179; genetics and, 28, 100, 102, 105, 136, 169, 178; as “hard-wired” instinct, 47, 178; as learned from social groups, 47, 49, 172–73, 179; observation as motivation of de-extinction, 20; and vulnerability to extinction, 5
Belyaev, Dmitry, 170
biodiversity: ancient DNA and, 55; de-extinction and, 9, 16, 130, 163–64; extinction and, 5–7, 159–63; as motivation for de-extinction, xi, 16, 30–31, 130, 163– 64; rewilding and, 159–63, 188
biodiversity conservation, 16, 163–64, 193, 203, 206
birds: California condor recovery project, 115, 175–81, 207; as candidates for de-extinction, 20–22, 50, 156; cloning and, 153–59, 191; extinction and, 15, 34. See also chickens; moas; passenger pigeons
bison: Bison latifrons, 71; hybridization and, 28; in Pleistocene Park, 38–39, 164; re-wilding and, 160; steppe bison, 2–5, 10, 12, 28, 65, 68–69, 98
Brand, Stewart, 8–9, 48–50, 115, 184, 189–90, 192–93, 203, 205–6
bucardos (Pyrenean ibex), 7–8, 48, 142–47, 182, 196
Buigues, Bernard, 73–76, 84–85, 87, 90
Buigues, Sylvie, 75
California condors, 115, 175–81, 207
candidate species for de-extinction: behavior as factor, 31, 47, 172–73, 199; bucardo as, 142; Cascade Mountains wolf as, 26–27, 30; costs as factor, xi, 14, 31, 48, 193, 196; dodo as, ix–x, 17, 22–24, 35, 42, 64, 197; generation time as factor, 50, 107, 177; habitat availability as factor, 17, 18, 26, 35–39, 47–48, 160, 184–85, 197–202; Lazarus frog as, 8; living, related species as factor, 11, 20, 30–31, 45, 47, 147; mammoth as, ix–x, 11–14, 38–39, 49, 71, 149–50, 151, 164–65; megafauna as, 24–25, 81–82, 160; moa as, 20–22, 31; passenger pigeon as, ix, 9, 16, 32–33, 37– 38, 49–50, 71, 115, 153, 178; recent extinction as factor, 15, 32, 142; Steller’s sea cow as, 46, 152, 194, 197; subspecies as, 27–30; technology development as fact, 39–47; Yangtze River dolphin as, 19–20, 24, 199
captivity, 194; breeding in, 146, 169–72; captive rearing and behavior, 31, 47–48, 169–71, 175–79; and psychological stress, 169, 170, 172
Cascade Mountains wolf, 17, 26–27, 30
cattle, 28, 102–3, 107; cloning of, 143. See also aurochs
caves, DNA preserved in, 64–65, 70–71
CERPOLEX (CERcles POLaires EXpédition), 73–74
chestnut trees, American, 37, 205–6
Church, George, 8, 49, 115–17, 125, 130, 133, 135, 140; joke, 164, 191, 196
climate: benefits of mammoth reintroduction to, 165; as important for DNA preservation, 57, 64–66, 70–71, 83–84. See also climate change; habitat
climate change: as cause of extinction, 1–5, 7, 191; as driving adaptation, 14–15, 205; as natural, 7
clones: banteng, 137–38, 143; bucardo, 7, 142–43; congenital defects in, 8, 81, 142– 44; Dolly the sheep, 7–8, 44–45, 78–79, 81; following de-extinction, regulation of, 187; guar, 137–38, 142–43; human, 93–94; of pets as commercial service, 81; Promotea the horse, 81; Snuppy the dog, 81, 93–94
cloning: ancient DNA and, 11; birds, 144, 153–56, 191; cell line generation and, 91– 93, 166; commercial applications of, 81, 156; congenital defects as a result of, 8, 81, 142–44; cross-species, 145; as de-extinction technology, 8, 141, 149–51, 166; germ cell transfer and, 154–58; of mammoths (announced or attempted), 8, 85–89, 92–95; of mice from frozen cells, 91–92; by nuclear transfer, 7–8, 44–46, 77–81, 78, 85, 88–89, 92–93, 127, 143–45
cold: and preservation of DNA, 64, 68–71, 69, 81–84, 95–96
cold tolerance: in elephants as requirement for engineering mammoths, 14, 46, 49, 100, 108, 131–32, 163–64; mammoth-specific hemoglobin, 55, 107– 8, 123, 124, 131, 133; Ucp1 gene and, 46
condor, California. See California condors
conservation: de-extinction as tool for, xii, 16, 163–64, 189–93; ecosystem management and, 201–2; funding for, 48, 196– 98; genetic engineering to enhance living species, 205–6; prioritizing living species, 195–97; public opinion toward, 48, 197, 207; rewilding as tool for, 187– 88, 202
contamination of ancient DNA, 42–43, 56–58, 60–63, 70
Cooper, Alan, 84
costs of de-extinction, ix, 9, 14–15, 48–49, 193, 195–97; DNA sequencing as expense, 110, 113, 135; management of de-extinct species, 48, 196; and species as candidates for, 31
Creak, James, 126
Crichton, Michael, 56
CRISPR (clustered regularly interspaced short palindromic repeat) systems for genome engineering, 121–23, 123, 133–35
Crister, John, 150
de-extinction, ix–xii; back-breeding as means of, 99–107; behavioral aspects of, ix–x, 11, 168–71; cloning technology and, 141; and ecosystem restoration, 10, 12, 130–31, 205; effect on human population, 37–38; feasibility of, 25–26; in fiction, ix, 9–10, 45, 56, 112–13, 126–29; funding of projects, 48, 85–86, 195–97; and habitat revitalization, 15; management of resurrected species, 201–2; media and popular conceptions of, 125, 190–91; politics of, 203 (See also regulation under this heading); and public interest in conservation, 197–98; of recently extinct species, 32; and reconstruction of ancient DNA, 111–13; regulation of resurrected species, 181–87; risks of, xi, 188, 189, 201, 207; and species enhancement, 206–7; time frame for, xi–xii, 116– 17, 125, 177; wild, self-sustaining population as goal, 25, 47–48
de-extinction technologies: back-breeding, 99–105; cloning, 11, 44–45, 77– 81, 145 (See also nuclear transfer under this heading); genome editing, 11, 45–46, 107– 8, 115–24; germ cell transfer, 79, 154–58, 182; nuclear transfer, 77–81, 144–45, 147 (See also cloning under this heading); synthesizing genomes, 109–15
deforestation, as cause of extinction, 31–35, 180, 197–98
Denisovans, 139
desiccation, and preservation of DNA, 65
development, embryonic and prenatal, 13, 79–80, 151–53, 158; in birds, 153–55, 158. See also gestation
disease: accidental de-extinction of, 193–94; genome editing as medical therapy, 120, 122
DNA: in cells, 62; degradation after death of organism, 77–78; extracting ancient, 51–53; PCR (polymerase chain reaction) and amplification of, 58–61; repair, 119– 20; structure of, 40, 40–41. See also ancient DNA
DNA, preservation of: in amber, insert, 45, 51–54, 56–58, 60–61; caves, 64–65, 70–71; climate and, 57, 64–66, 70–71, 83– 84; desiccation and, 65; in mummies, 65, 74, 83–84, 89–91; in permafrost, 64, 68–71, 81–84, 95–96
DNA sequences: composition of, 12–13, 39–41; synthetic, 109–11, 115–17, 120, 122, 135. See also DNA sequencing
DNA sequencing: of ancient DNA, xi, 10–11, 39–45, 53, 56–58, 69–70, 111–15; cost of, DNA sequences, 113, 135; technologies for, 58, 113–14, 135. See also genome sequencing and assembly
dogs, 76; cloning, 81, 93–94, 144–45; mammoth eaten by, 89–90; selective breeding and domestication of, 101–2
Dolgans (Siberian reindeer herders), 96–98
Dolly the sheep, 8, 44–45, 78–81
domestication, 58, 170; selective breeding and, 100–102, 204
double-clutching, 176
dugongs, as surrogate hosts, 46, 152
ecological resurrection, as goal of de-extinction, 10, 131, 187–88
ecosystems: adaptation to loss of species, 30, 32, 36–39, 130, 201; ecological resurrection as goal of de-extinction, 10, 131, 187–88; interactions among species, 201; invasive species and extinction, 34–35; living species as proxies for extinct species in, 160–63; mammoth reintroduction and, 14–15, 164–65; reintroduction of animals to, xi, 27–30, 38, 191, 199–201, 207; unpredictable impacts of de-extinction on, xi, 9, 32, 36–37, 188
ectogenesis. See artificial wombs
egg cells, 79; elephants as egg donors, 149–50; and nuclear transfer, 46, 78, 147–48
elephants: captivity and, 171–72; cold-tolerance and, 13–14, 46, 129, 163; as egg donors, 149–50; as endangered, 149–50; genetic engineering to recreate mammoth-like traits, 129, 207; genomics of, 132; introduction to North America, 162; as living relatives of mammoths, 11–12, 54, 111–13, 112, 132; as proxies for mammoths in ecosystem, 163–65; social behavior of, 180; as source of genetic material, 119; as surrogates for mammoths, 107, 150–51
endangered species: cloning of, 137–38; de-extinction as political threat to, 203; GMOs as, 185–87; limited genetic diversity linked to low populations, 9
Endangered Species Act, 185–86
enucleation, 79
ethics, scientific, xii, 115; cloning and, 93–94; and de-extinction, 9, 13–16, 25, 203 (See also risks of de-extinction). See also animal welfare
euchromatin, 114
Extinct DNA Study Group (UC Berkeley), 55–56
extinction: causes of (See extinction, causes of); contemporary age of, 5–7; mass extinction events, 1–2, 6; reversal of (See de-extinction); trophic cascade and, 130
extinction, causes of: cataclysmic events, 2–3; climate change, 1–5, 7, 191; habitat destruction, 34–35, 180; humans or human activity, 4–5, 7, 22–24, 26, 32–36, 142; introduction of predators, parasites, and competitors, 34–36; overexploitation, 4–5, 22, 33–34, 36, 142, 180, 185, 197–98
fear: of de-extinction, xi, 127, 193–204; of extinction as concept, xi, 6
Fernández-Arias, Alberto, 143–44
first phase of de-extinction, 11, 15, 116–17, 166
fish, 157
fossils: dating, 66–68; as DNA sources, 63–70, 113–14 (See also amber, DNA preserved in)
Fox, David, 75
Froese, Duane, 69
frogs, 8, 53, 80–81, 112–13, 190–91, 200
Frozen Zoo, San Diego, 9
funding for de-extinction projects, 195–97
gametes, 79. See also egg cells; sperm cells
generation time: and candidacy for de-extinction, 50, 107
genes: interaction of, 106
genetically modified organisms (GMOs): as endangered species, 185–87; genome editing and, 120, 182–83; regulation of, 181–87
genetic diversity: and adaptive potential, 167–68; of ancient populations, 66; as consequence of cloning, lack of, 166– 68; in de-extinct species, 166–68, 185; genomic editing and, 166–68
genetic engineering: and adaptation to changing environment, ix–x, 10; of chickens, 156–58; and conservation of threatened species, 205–7; costs of, 110– 11; and creating synthetic life, 109–11; and creation of genetically diverse populations, 166–68; as de-extinction technology, 8, 30, 141; of elephants, 165, 177; and restoration of genetic diversity within a species, 9; selective breeding as, 100–105, 204; technologies for (See primordial germ cell transfer; somatic cell nuclear transfer). See also cloning; genome editing
genome editing, 115–21; CRISPR/Cas9 technology, 121–24, 133–34; as de-extinction technology, 45–46; genetic diversity and, 166–68; and mammoth de-extinction, 45–46, 124, 128, 129, 133, 138, 147–48, 152; medical applications of, 120, 122; “molecular” scissors and, 118–21; primordial germ cells and, 154– 55, 182; and resurrection of traits, 163– 64; selecting gene targets for, 45, 117–19, 131–36, 138–39, 152; somatic cell nuclear transfer and, 129; stem cells and, 123– 24; successful applications of, 120; technology for, 118–21
genome engineering. See genome editing
genomes: components of, 114; of extinct organisms and species, 10–11, 13, 30–31, 39–44, 70–71, 111–15; synthetic, 109–11, 113. See also genome sequencing and assembly
genome sequencing and assembly: of ancient organisms, 39–45, 66; costs of, 110, 113, 135, 196; of horse, ancient, 66; of human, 114, 138; and identification of genes for editing, 138–39; of mammoth, 13, 63, 111–13, 117–18, 132–33, 138; of passenger pigeon, 50, 117, 196; process of, 41–44; technologies for, 41, 109–15. See also DNA sequencing
germ cells, 79
germ cell transfer. See primordial germ cell transfer
gestation, 49; in artificial wombs, 152–53, 195; and de-extinction of mammoths, 49, 107, 151; environmental factors and, 137–38. See also development, embryonic and prenatal; surrogacy
Ghorokov, Vasily, 87
GMOs. See genetically modified organisms (GMOs)
gold mining, 68–69; and exposure of remains, insert
Göring, Hermann, 102
guilt, as motive for de-extinction, 26
habitat: destruction as cause of extinction, 34–35, 180; as requirement for de-extinction, 20, 24, 25, 35–36, 39, 180, 198–99; and selection of species for de-extinction, 36; suitability for reintroduction and, 39, 163. See also climate
hair as DNA source, 86
hemoglobin, mammoth-specific, 107–8, 123, 124, 131
homologous recombination, 120
horses, 2–5, 106, 161–62; ancient DNA extracted and sequenced, 66–70; clones, 81; evolution and local extinctions of, 55
human-caused extinction, 4–5, 7, 22–24, 32–36, 142; and guilt as motive for de-extinction, 26
humans: extinction caused by (See human-caused extinction); as lacking in genetic diversity, 168; and manipulation of nature, 204; sequencing of human genome, 114, 138
hunting: as motive for de-extinction, 102; overexploitation as cause of extinction, 4–5, 22, 33–34, 36, 142, 180, 185, 197–98; restrictions on, 37–38; resurrected mammoths, 187
hybrids: brown bear–polar bear, 28–29; dog-wolf-coyote, 28; Florida panther– Texas panther, 167; genomic challenges of, 148; human–Neandertal, 28; ibex-goat, 7, 145–47; mammoth-elephant, 86–87, 126, 129–30; as result of de-extinction, xi, 22, 86–87, 147; and sterility, 127–28
ice ages. See glaciations
induced pluripotent stem cells (iPSCs), 80–81
invasive species, 171, 198, 199, 202; de-extinct species as, 181–82; and extinctions, 34–35
Iritani, Akira, 8, 86–89, 92–93
island restoration projects, 202–3
J. Craig Venter Institute, 109–11
Jurassic Park (movie), 45, 56, 112–13
kangaroo rats, 15, 26, 49, 197
Kerkdijk-Otten, Henri, 100–101
Khatanga research base, Krasnoyarski Krai district, Siberia, 73–76, 85
Khundi, Yuri, and sons, 89
Klondike gold fields, Yukon, 68–69
lactic acid and mummification, 90–91
Lazarus frog de-extinction project, 8, 190
Leitch, George, 22
Linnaeus, Carl, 29
Long Now Foundation, 115
Malolyakovsky Island, 96
Mammoth Creation Project, 86–87
Mammoth Museum, Yakutsk, 86
mammoths: as candidates for de-extinction, ix–x, 11–14, 38–39, 49, 71, 149–50, 151, 164–65; cold-tolerance of, 107–8, 123; ecological reasons for de-extinction of, 49, 164–65; elephants as evolutionary relatives, 11–12, 54, 111–13, 112, 132; elephants as surrogates for, 49, 150–51; genome sequence of, 111–13, 135– 36; recreation of habitat for, 38–39
Mammuthus (organization), 73–74
Martha, the last known passenger pigeon, insert
Mauritian giant tortoise, 202–3
Mayr, Ernst, 28
media, and de-extinction, 125–29, 189–91
megafauna: as candidate species for de-extinction, 24–25, 81–82, 160; and interest in conservation, 197; proxies for extinct, 187–88; role within ecosystem, 165, 195
microbiome, de-extinction of, 13
mitochondrial DNA, 61–62, 62, 71, 86, 111–12, 147–48
moas: as candidate species for de-extinction, 20–22, 24, 31, 158, 182; as genetically modified species, 182; recovery of ancient DNA from, 54–55, 64; skeleton reconstruction, 21; taxonomy of, 31, 54–55
Monbiot, George, 195
motivations for de-extinction, 17–18, 20, 48–50
Mullis, Kary, 58
mummies: DNA preservation in, 65, 74, 83–84, 89–91; the search for, 84–86, 91, 94–98. See also Jarkov mammoth; Lyuba mammoth; Yukagir mammoth
Mycoplasma mycoides JCVI-syn1.0, 109–10
mythology, mammoths in, 83, 89
National Geographic, 94
Neandertals, 6, 28–29, 42–44, 54, 70, 139
Nenets (Siberian reindeer herders), 89
Nicobar pigeons, 54
noncoding (“junk”) DNA, 45, 134–35
non-homologous end joining, 120
nuclear genome, 62
nuclear transfer: as de-extinction technology, 144–45, 147; success rates, 127, 143, 167
overexploitation, as cause of extinction, 4–5, 22, 33–34, 36, 142, 180, 185, 197–98
Owen, Sir Richard: with moa skeleton, 21
Pasha the dog, 76
passenger pigeons: and Allee effect, 180; as candidates for de-extinction, ix, 9, 16, 32–33, 37–38, 49–50, 71, 115, 153, 178; ecology of, 37–38, 172, 180; engineering using band-tailed pigeon, 155, 177–78, 205; extinction of, 32–33; flock of migrating, 33; homing pigeons as surrogate flocks for, 172–73; leg bones of, insert; Martha, the last known, insert; rewilding and regulation of, 182–87; sequencing the genome of, 50, 117, 196
pathogens: CRISPR technology and, 121–22; de-extinction and risk from, 193–94; genomic editing of, 121–22; recovery of from ancient remains, 43
PCR (polymerase chain reaction), 58–61, 59
Pennsylvania Sate University, 1, 70
permafrost: carbon sequestration and, 165; preservation of DNA and remains in, 64, 68–71, 81–84, 95–96
phases of de-extinction: first phase, 11, 15, 116–17, 166; second phase, 12, 15, 166, 168–69, 191
Phelan, Ryan, 8–9, 49–50, 115, 184, 189–90, 205–6
phenotype, 13, 100, 104, 106, 124, 136; and epigenetics, 136–40
Pleistocene Park, insert, 8, 38–39, 86, 164–65, 177, 187, 207
population: Allee effect and stability of, 180; defined, 28–30; as defined by the Endangered Species Act, 185–87; genetic diversity within, 100, 104, 138–39; reconstructing the evolutionary history of, 10–11, 55, 66; sustainability and size of, 166–69, 179–80, 198
predators: de-extinction of, 199; ecosystem restoration and introduction of, 162–63; ecosystem role of, 26–27
prenatal development. See development, embryonic and prenatal
preservation of DNA. See DNA, preservation of
Pribilof Islands, 2
primordial germ cell transfer, 79, 154–58, 182
protection. See regulation
public opinion, 9, 127–30, 162–63, 203; about environmental conservation, 197, 207; about genetically modified organisms, 181–87; about reintroduced species, 200; about rewilding, 162–63, 187– 88; appeal as criterion for selection of de-extinction candidates, 49–50, 197; fear of de-extinction, 204; media and, 189–92
pygmy mammoths, 152
quaggas, 54
recombination, 104; homologous, 120; sexual reproduction and, 104
re-extinction, x, 12; accidental, 172–73, 179; as method to correct errors, 199–200
regulation: of GMOs, 181–87; and protection of de-extinct species, 22, 38, 184– 87; and protection of endangered species, 36, 184–87, 185; of reintroduced species, 162, 181–86, 200–201
reintroduction: of captive-bred animals, 176–81; challenges of, 37–38, 47–48, 173, 178–79, 181; cost of, 196–97; of de-extinct animals, 12, 47–48, 130–31, 166–69, 195– 97; and environmental impact, 20, 27, 36–37, 199–201; as goal of de-extinction, 12, 130–31; and regulation post-release, 162, 181–86, 200–201; of wolves, 27–28. See also rewilding
reproduction, sexual: and captive breeding, 169–72; and homologous recombination, 120; rearing offspring, 168–69; selective breeding, 100–105, 170; sterility of hybrids, 127–28; surrogacy and, 31, 46–47
retro-breeding. See back-breeding
Revive & Restore, 8–9, 48–49, 115, 123, 184, 196
rewilding: as conservation tool, 187–88, 202; of Europe, plan for, 131, 195; of feral horses in the Americas, 55; of North America, plan for, 159–63; public opinion about, 162–63, 187–88. See also reintroduction
rhinos, woolly, 177
risks of de-extinction, xi, 188, 189, 201, 207
Roslin Institute, 44–45, 78–79, 81, 156, 158
Rountrey, Adam, 75
Ryder, Oliver, 9
science fiction and de-extinction, ix–x
second phase of de-extinction, 12, 15, 166, 168–69, 191
selective breeding, 170; and back-breeding, 100–107; and domestication, 101–2, 204; as genetic engineering, 204; and length of gestation period, 107
sequencing DNA. See DNA sequencing
Siberia: fossil hunting in, insert
Snyder, Noel, 115
somatic cell nuclear transfer, 45, 77–81, 78, 143–45, 147–48; genome editing/engineering and, 129. See also nuclear transfer
somatic cells, 79; and development of cell lines, 92; reprogramming and, 145. See also somatic cell nuclear transfer
Sooam Biotech Research Foundation, 94–95
South Korea, 93
Spanish ibex, insert. See also bucardos (Pyrenean ibex)
species confusion, 179
sperm cells, 79; viability of frozen, 86–87
Steller’s sea cows, 33–34, 34, 46, 197
stem cells, 79–81, 89, 94, 145; and genome editing, 123–24; medical applications of, 80, 94
steppe bison, 2–5, 12, 28, 68–69
subspecies: as candidates for de-extinction, 27–30; geographic barriers and emergence of, 29–30
surrogacy, 31, 46, 78–79, 81, 151–52; elephants as hosts, 49, 150–51; evolutionary distance as factor, 147; size differences as factor, 46, 151–52
Sweeny, Mike, 192
taxonomic system, 29
TEDx De-Extinction, 9, 48–49, 172–73, 189–91
Temple, Stanley, 191
Thismia americana, 17
thyroid-stimulation hormone receptor (TSHR), 58–60
tortoises, 160–61, 178–79, 202–3
traits: back-breeding for specific, 102–5; gene expression and multiple, 105–6
transcription activator-like effector nucleases (TALENs), 118–21, 119
trophic cascade, 130
Turvey, Sam, 19
tusks, mammoth, 75, 87, 90, 95
ultraviolet light, DNA damage and, 64
University of California, Santa Cruz, 17–18
Vasiliev, Vasily, 93
viruses, resurrection of, 193–94
welfare, animal. See animal welfare
wolves, 26–27, 29–30, 101–2, 198, 207
World Expo, Aichi, Japan, 88
Wyss Institute, 8, 49, 115, 122
Yangtze River dolphin, 17, 18–20, 24, 35, 199
Yasmilov, Sverbighooze, 126
Yellowstone National Park, 27, 198, 207
Yoshizaki, Goto, 157
Yukagir mammoth, 87–89, 92–93; ice cave storage for, insert
Zimmer, Carl, 189
Zimov, Sergey, 8, 38–39, 86, 164–65, 187
zinc finger nucleases (ZFNs), 118–21, 119
zoos, 14; captivity and psychological stress, 169, 170, 172; Frozen Zoo, San Diego, 9; reproduction in, 169