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Authors: Carl Sagan,Ann Druyan

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Chapter 6
US AND THEM
 

1.
Book XXII, line 262.

2.
Lynn Margulis,
Symbiosis in Cell Evolution
(San Francisco: W. H. Freeman, 1981).

3.
Andrew H. Knoll, “The Early Evolution of Eukaryotes: A Geological Perspective,”
Science 256
(1992), pp. 622–627.

4.
Margulis,
op. cit
.

5.
L. L. Woodruff, “Eleven Thousand Generations of
Paramecium,” Quarterly Review of Biology 1
(1926), pp. 436–438.

6.
Z. Y. Kuo, “The Genesis of the Cat’s Response to the Rat,”
Journal of Comparative Psychology 11
(1930), pp. 1–30.

7.
Benjamin L. Hart, “Behavioral Adaptations to Pathogens and Parasites: Five Strategies,”
Neuroscience and Biobehavioral Reviews 14
(1990), pp. 273–294.

8.
George C. Williams and Randolph M. Nesse, “The Dawn of Darwinian Medicine,”
Quarterly Review of Biology 66
(1991), pp. 1–22.

9.
Harry J. Jerison, “The Evolution of Biological Intelligence,” Chapter 12 of Robert J. Sternberg, editor,
Handbook of Human Intelligence
(Cambridge: Cambridge University Press, 1982), Figure 12–11, p. 774.

10.
A view championed in recent times by the neurophysiologist Paul D. MacLean and described in Carl Sagan’s
The Dragons of Eden: Speculations on the Evolution of Human Intelligence
(New York: Random House, 1977). MacLean sets forth a comprehensive summary of his views in
The Triune Brain in Evolution: Role in Paleocerebral Functions
(New York and London: Plenum Press, 1990).

11.
This approach is made most accessible to the general reader in Richard Dawkins’s book
The Selfish Gene
, revised edition (Oxford: Oxford University Press, 1989). In a vivid passage (pp. 19–20), he describes the genes as swarming “in huge colonies, safe inside gigantic lumbering robots, sealed off from the outside world, communicating with it by tortuous indirect routes, manipulating it by remote control. They are in you and me; they created us, body and mind; and their preservation is the ultimate rationale for our existence … [W]e are their survival machines.”

12.
A related and even more heated controversy—on whether the mother bird has any notion of what she’s doing or is merely some carbon-based automaton—is addressed later in this book. Reciprocal altruism, an exchange of present for future favors, is also admitted by those who deny group selection per se.

13.
Martin Daly and Margo Wilson,
Homicide
(New York: Aldine de Gruyter, 1988), pp. 88, 89.

14.
W. D. Hamilton, “The Genetical Evolution of Social Behavior,”
Journal of Theoretical Biology
7 (1964), pp. 1–51; John Maynard Smith, “Kin Selection and Group Selection,”
Nature 201
(1964), pp. 1145–1147.

15.
Imagine that the huddled group (of, say, insects) is in the shape of a sphere. The heat generated by the group is proportional to its volume (to the cube of its size), but the heat radiatively lost by the group is proportional to its area (to the square of its size). Thus the bigger the group is, the more heat it retains. In a large group, only a small proportion of members are on the surface of the sphere, where an individual is exposed to the cold; the remainder are satisfyingly surrounded by warm bodies on all sides. The smaller the group is, the greater the proportion of individuals on the chilly periphery.

16.
Up to some limit, when the individuals doing the mobbing get in each other’s way.

17.
Dawkins,
op. cit.
, p. 171, citing the work of Amotz Zahavi.

18.
Ibid.
, Preface to 1989 edition. For an opposing, now minority, point of view, see V. C. Wynne-Edwards,
Evolution Through Group Selection
(Oxford: Blackwell, 1986): “The view, widely held, that group selection can be dismissed as an effective evolutionary force is based on assumptions, not on evidence … It is an argument uncritically derived from human experience, of cheaters, criminals and oppressors who live at other people’s expense; and it ignores the fact that all viable kinds of exploiters in the animal world must be able when necessary to limit their own numbers” (p. 313).

It seems strange that, in the real world as well as in contrived optical illusions, two completely different interpretations can give equivalent results. But this is a commonplace in physics—in quantum mechanics, say, or in the study of elementary particles—where two approaches with different starting assumptions and different mathematical apparatus turn out to give identical quantitative answers, and are therefore understood to be equivalent formulations of the solution to the problem.

19.
K. Aoki and K. Nozawa, “Average Coefficient of Relationship Within Troops of the Japanese Monkey and Other Primate Species with Reference to the Possibility of Group Selection,”
Primates 25
(1984), pp. 171–184; J. F. Crow and Kenichi Aoki,
“Group Selection for a Polygenic Behavioral Trait: Estimating the Degree of Population Subdivision,”
Proceedings, National Academy of Sciences 81
(1984), pp. 6073–6077.

20.
Aoki and Nozawa,
op. cit
.

21.
Jules H. Masserman, S. Wechkin, and W. Terris, “ ‘Altruistic’ Behavior in Rhesus Monkeys,”
American Journal of Psychiatry 121
(1964), pp. 584, 585; Stanley Wechkin, J. H. Masserman, and W. Terris, “Shock to a Conspecific as an Aversive Stimulus,”
Psychonomic Science 1
(1964), pp. 47, 48.

22.
Especially when there is an authority figure urging us to administer the electric shocks, we humans seem disturbingly willing to cause pain—and for a reward much more paltry than food is for a starving macaque (cf. Stanley Milgram,
Obedience to Authority: An Experimental View
[New York: Harper & Row, 1974]).

23.
Translated by Richmond Lattimore (Chicago: The University of Chicago Press, 1951), Book XXI, lines 463–466, p. 430.

 
Chapter 7
WHEN FIRE WAS NEW
 

1.
Fragment 118 in
Herakleitos and Diogenes
, Guy Davenport, translator (Bolinas, CA: Grey Fox Press, 1979).

2.
Jonathan Barnes, editor,
Early Greek Philosophy
(Harmondsworth, UK: Penguin Books, 1987), p. 104.

3.
Wen-Hsiung Li and Dan Graur,
Fundamentals of Molecular Evolution
(Sunderland, MA: Sinauer Associates, 1991), pp. 10–12.

4.
B. Widegren, U. Arnason, and G. Akusjarvi, “Characteristics of Conserved 1,579-bp High Repetitive Component in the Killer Whale,
Orcinus orea,” Molecular Biology and Evolution 2
(1985), pp. 411–419 (bp is an abbrevation for nucleotide basepairs, the letters in the genetic sequences).

5.
It can be very serious on the human level. For example, on Chromosome 19 most people have a sequence of nucleotides that goes CTGCTGCTGCTGCTG, a five-fold repeat. But some have hundreds or even thousands of consecutive CTG sequences, and they suffer in consequence from a grave disease called myotonic dystrophy. Some other genetic diseases may have a similar cause.

6.
M. Herdman, “The Evolution of Bacterial Genomes,” In
The
Evolution of Genome Size
, T. Cavalier-Smith, ed. (New York: Wiley, 1985), pp. 37–68.

7.
Richard Dawkins,
The Blind Watchmaker
(New York: Norton, 1986), pp. 46–49.

8.
J. W. Schopf, private communication, 1991; Andrew W. Knoll, “The Early Evolution of Eukaryotes: A Geological Perspective,”
Science 256
(1992), pp. 622–627.

9.
Philip W. Signor, “The Geologic History of Diversity,”
Annual Review of Ecology and Systematics
21 (1990), pp. 509–539.

10.
Sewall Wright,
Evolution and the Genetics of Populations: A Treatise in Four Volumes
, Volume 4,
Variability Within and Among Natural Populations
(Chicago: The University of Chicago Press, 1978), p. 525.

11.
Sewall Wright, “Surfaces of Selective Value Revisited,”
The American Naturalist
131 (1) (January 1988), p. 122. This article was written when the pioneering population geneticist was ninety-eight.

12.
Cf. Ilkka Hanski and Yves Cambefort, editors,
Dung Beetle Ecology
(Princeton: Princeton University Press, 1991); Natalie Angier, “In Recycling Waste, the Noble Scarab Is Peerless,”
New York Times
, December 19, 1991.

13.
Charles Darwin,
Origin of Species
, quoted in John L. Harper, “A Darwinian Plant Ecology,” in D. S. Bendall, editor,
Evolution from Molecules to Men
(Cambridge: Cambridge University Press, 1983), p. 323.

14.
Clair Folsome, “Microbes,” in T. P. Snyder, editor,
The Biosphere Catalogue
(Fort Worth, TX: Synergetic Press, 1985), quoted in Dorion Sagan,
Biospheres: Metamorphosis of Planet Earth
(New York: McGraw-Hill, 1990), p. 69.

 
Chapter 8
SEX AND DEATH
 

1.
George Santayana,
The Works of George Santayana
, Volume II,
The Sense of Beauty: Being the Outlines of Æesthetic Theory
, edited by William G. Holzberger and Herman J. Saatkamp, Jr. (Cambridge: The MIT Press, 1988), Part II, §13, p. 41.

2.
Richard Taylor, editor, quoted in George Seldes,
The Great Thoughts
(New York: Random House, 1985), p. 373.

3.
The first clear explanations of sex both as a means of rapid evolution and as an escape of populations—especially small populations—from the cumulative impact of deleterious mutations were made by the geneticist H. J. Muller (e.g., “Some Genetic Aspects of Sex,”
American Naturalist 66
[1932], pp. 118–138; “The Relation of Recombination to Mutational Advance,”
Mutation Research 1
[1964], pp. 2–9). There is theoretical and experimental support for his proposals (e.g., Joseph Felsenstein, “The Evolutionary Advantage of Recombination,”
Genetics
78 [1974], pp. 737–756; Graham Bell,
Sex and Death in Protozoa: The History of an Obsession
[Cambridge: Cambridge University Press, 1988]; Lin Chao, Thutrang Than, and Crystal Matthews, “Muller’s Ratchet and the Advantage of Sex in the RNA Virus Φ6,”
Evolution 46
[1992], pp. 289–299).

Muller stressed that sexual reproduction was hardly necessary for survival, but that “lack of recomination would greatly handicap a species, in long-term evolutionary advancement, in keeping pace with sexually reproducing competitors.” The idea of sex providing a long-term benefit for the species certainly seems to be an example of group selection, as was explicitly noted, without undue alarm, by one of the founders of modern population genetics, R. A. Fisher
(The Genetical Theory of Natural Selection
[Oxford: Clarendon Press, 1930]). Fisher was one of the first to suggest that, in other cases, what superficially looks like group selection may in fact be kin selection.

4.
D. Crews, “Courtship in Unisexual Lizards: A Model for Brain Evolution,”
Scientific American
259 (June 1987), pp. 116–121.

5.
Raoul E. Benveniste, “The Contributions of Retroviruses to the Study of Mammalian Evolution,” Chapter 6 in R. I. Maclntyre, editor,
Molecular Evolutionary Genetics
(New York: Plenum, 1985), pp. 359–417.

6.
We have scarcely touched on the complexity and diversity of the sexual machinery, both on the molecular level and the level of individual organisms. Nor have we given a full flavor of the debate on what sex is good for. An excellent short summary is in James L. Gould and Carol Grant Gould,
Sexual Selection
(New York: W. H. Freeman, 1989). See also the influential book by John Maynard Smith,
The Evolution of Sex
(Cambridge: Cambridge University Press, 1978); H. O. Halvorson and A. Monroy, editors,
The Origin and Evolution of Sex
(New York: A. R. Liss, 1985); Lynn Margulis and Dorion Sagan,
Origins of Sex
(New Haven: Yale University Press, 1986); R. E. Michod and B. R. Levin,
The Evolution of Sex
(Sunderland, MA: Sinauer, 1988); Alun Anderson, “The Evolution of Sexes,”
Science
257 (1992), pp. 324–326; and Bell,
op. cit
. in Note 3.

7.
D. J. Roberts, A. B. Craig, A. R. Berendt, R. Pinches, G. Nash, K. Marsh and C. I. Newbold, “Rapid Switching to Multiple Antigenic and Adhesive Phenotypes in Malaria,”
Nature
357 (1992), pp. 689–692.

8.
W. D. Hamilton, R. Axelrod, and R. Tanese, “Sexual Reproduction as an Adaptation to Resist Parasites (A Review),”
Proceedings of the National Academy of Sciences 87
(1990), pp. 3566–3573.

9.
Helen Fisher, “Monogamy, Adultery, and Divorce in Cross-Species Perspective,” in Michael H. Robinson and Lionel Tiger, editors,
Man and Beast Revisited
(Washington and London: Smithsonian Institution Press, 1991), p. 97.

10.
E. A. Armstrong,
Bird Display and Bird Behaviour. An Introduction to the Study of Bird Psychology
(New York: Dover, 1965), p. 305.

11.
W. D. Hamilton and M. Zuk, “Heritable True Fitness and Bright Birds: A Role for Parasites?”
Science 218
(1982), pp. 384–387.

12.
The same bargain is made in the common, sexually repressive version of the story of the Garden of Eden—in which it is sexual activity between Adam and Eve that excites God’s wrath and makes them mortal.

13.
This wonderfully vivid image is Frans de Waal’s, in
Peacemaking Among Primates
(Cambridge: Harvard University Press, 1989), p. 11.

14.
Translated by Edward Kissam and Michael Schmidt (Tempe, AZ: Bilingual Press/Editorial Bilingüe, 1983), p. 47.

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