79
But grinding and cooking changed the costs of digestion:
Boback et al. (2007).
81
Cooked food is better than raw food because life is mostly concerned with energy:
Female chimpanzees: Thompson et al. (2007), Williams et al. (2002). Energy and human reproduction: Ellison (2001).
Four: When Cooking Began
83
fire was not regularly used for cooking until the Upper Paleolithic:
Jolly and White (1995).
83
Others favor much earlier times, half a million years ago:
Aiello and Wheeler (1995), Rowlett (1999), Ragir (2000), Foley (2002).
83
physical anthropologist Loring Brace
: Brace’s specific ideas about the effects of cooking on tooth size reduction have not been widely followed, but Brace has done more to stress the potential importance of cooking than most recent anthropologists, and his interpretation of archaeological evidence as indicating that the control of fire began around a quarter of a million years ago seems to have been the dominant view in recent decades (e.g., James [1989] and commentators on his paper).
84
Abri Pataud:
Bricker (1995).
84
Abri Romani:
Pastó et al. (2000).
84
Vanguard Cave:
Barton et al. (1999). Pullen (2005) and Victoria Ling (personal communication) provide excellent reviews of fire evidence from the Lower Paleolithic onward.
84
Klasies River Mouth:
Pullen (2005).
84
Sodmein Cave:
Pullen (2005).
85
Kalambo Falls:
Clark and Harris (1985).
85
Hayonim:
Albert et al. (2003).
85
the older part of the record, going back in time from a quarter of a million years ago, has been improving in quality:
Another rich source of fire evidence is the 400,85-year-old site at Bilzingsleben, where Mania ([1995]; Mania and Mania [2005]) has argued that hearths exist outside of the dwellings and a further hearth is in the center of a circular pavement. The hearths take the form of localized and discrete patches of burning upon the ground.
85
Beeches Pit:
Gowlett (2006), Preece et al. (2006). Beeches Pit also contains some burnt bones. With respect to the reconstruction of events at the Beeches Pit fire, the distribution of artifacts around the hearth suggests that hominins were undertaking fireside knapping. In particular, the refitting of a series of around thirty flakes, two of which were indeed burnt, provides a direct link between the knapping undertaken by an individual and a fire. Although it is unknown whether the fire provided a focus for social interaction, it is a reasonable suggestion given that several different forms of biface were retrieved from this area (Gowlett et al. [2005]). In 2007, John Gowlett kindly took me to this quiet woodland where the slope from a former living site still angles down toward the site of an ancient pond. I squatted precisely where so long ago, someone appears to have knapped an ill-chosen flint by a fire.
86
Schöningen:
Thieme (2000, 2005). Originally, four spears were reported (Thieme [1997]), but Thieme (2000) reports “more than half a dozen,” without being specific as to exact number. One spear was found next to a horse pelvis (Thieme [1997]). All are carved from spruce (
Picea
sp.) except spear IV, which is made from pine (
Pinus
sp.). They are carved from individual trees with a dense concentration of growth rings. The trees were felled, debarked, and had the side branches removed. The tips of the spears are worked from the hardest part of the wood at the base of the tree. Spear VI is 2.5 meters in length.
87
Gesher Benot Ya’aqov:
Goren-Inbar et al. (2004).
87
“had a profound knowledge of fire-making”:
Alperson-Afil (2008), p. 1733.
87
Archaeological sites between a million and a million and a half years old:
James (1989).
88
Others accept the idea that humans controlled fire in the early days of
Homo erectus
as well established:
Rowlett (1999), Boyd and Silk (2002).
88
the Hadza:
Mallol et al. (2007).
88
the half-lives of caves average about a quarter of a million years:
John Gowlett and Alfred Latham, personal communication, November 2006. Swartkrans (more than one million years old) is a cave made of dolomite, which resists erosion.
88
people must have used fire, yet there is no sign of it:
Recent sites without fire despite abundant evidence of fire in contemporaneous sites in the same region include High Cave in Tangier, Bisitun in Iran, Grotte Suard in Charente (Oakley [1963]). Likewise Sergant et al. (2006) report that in the cover sand area of the northwest European Plain, burnt bone, shells, and artifacts have been found on nearly every Mesolithic site (i.e., within the last ten thousand years prior to the introduction of farming), yet there are no structured hearths and the visibility of the “campfire” is extremely poor or in many sites unknown altogether.
88
mysterious reductions in the frequency of finding evidence of fire:
Victoria Ling (personal communication, 2007).
90
Anthropologists have sometimes suggested:
Stahl (1989), p. 19, suggests that “use of controlled fire as a source of warmth may have preceded systematic use of fire in food preparation by thousands or hundreds of thousands of years.”
90
Victoria Wobber and Brian Hare tested chimpanzees and other apes:
Wobber et al. (2008).
90
Chimpanzees in Senegal do not eat the raw beans of
Afzelia
:
Brewer (1978).
91
“Koko indicated the ‘tastes better’ option”:
Penny Patterson, personal communication, May 2007.
91
sensory nerves in the tongue:
Hiiemae and Palmer (1999).
91
brain cells (neurons) responsive to texture converge with taste neurons:
Kadohisa et al. (2005b).
91
such factors as grittiness, viscosity, oiliness, and temperature:
Kadohisa et al. (2004), Kadohisa et al. (2005a).
91
Edmund Rolls found when people ate foods of a particular viscosity:
de Araujo and Rolls (2004) used fMRI to assess neural responses in twelve subjects being given sucrose, vegetable oil, or solutions of carboxymethyl cellulose of known viscosity. Rolls (2005) gives an overview.
92
Studies of Galapagos finches by Peter and Rosemary Grant:
Galapagos finches,
Geospiza fortis
: Boag and Grant (1981), Grant and Grant (2002). After the intense selection for larger beaks, food became abundant and beak size returned slowly to its smaller original size. Weiner (1994) describes the Grants’ research.
93
In fewer than eight thousand years, mainland boa constrictors:
Boback (2006).
93
According to evolutionary biologist Stephen Jay Gould:
Gould (2002).
93
Loring Brace suggested:
Brace (1995). The pattern of decline in the size of chewing teeth is now known to be more complex than Brace suggested (Bermudez de Castro and Nicolas [1995]).
94
When fruits are scarce, gorillas rely on foliage alone:
The contrast in diet is probably due to food spending a longer time in the gut of gorillas, allowing more opportunity for fermentation of plant fiber and so giving gorillas more ability to survive on this lower-quality food. See Milton (1999). Wrangham (2006) compares behavior and ecology of chimpanzees and gorillas.
95
gorillas mature earlier:
Gorilla first birth is around nine years, compared to around fourteen years for chimpanzees; gorilla interbirth interval averages every 3.9 years, compared with chimpanzees every 5.0-6.2 years (Knott [2001]). A leaf diet might allow a predictable food regime sufficient to permit the evolution of rapid rates of growth and reproduction.
95
The anatomical differences between a cooking and a precooking ancestor:
Wrangham (2006).
96
largely complete by around two hundred thousand years ago.
Earliest
Homo sapiens
: White et al. (2003).
96
Homo heidelbergensis
was merely a more robust form of human than
Homo sapiens
:
Lieberman et al. (2002).
97
Homo heidelbergensis
evolved from
Homo erectus
:
Rightmire (1998, 2004). Cranial capacity increased from around 900 cubic centimeters (54.9 cubic inches) in
Homo erectus
to about 1,200 cubic centimeters (73.2 cubic inches) in
Homo heidelbergensis
.
97
the original change, from habilines to
Homo erectus
:
Anton (2003), McHenry and Coffing (2000). Areas of chewing teeth are totals for the second premolar and the first two molars. They totaled 478 square millimeters (0.74 square inches) in
Australopithecus (Homo) habilis
, compared to 377 square millimeters (0.58 square inches) in early
Homo erectus.
98
42 percent increase in cranial capacity:
Australopithecus (Homo) habilis
: 612 cubic centimeters (37 cubic inches).
Homo erectus
: 871 cubic centimeters (53 cubic inches) (McHenry and Coffing [2000]).
99
The only nonhuman primate that regularly sleeps on the ground:
Mehlman and Doran (2002).
99
early Pleistocene periods in Africa were rich in predators:
Werdelin and Lewis (2005).
100
The famous “Turkana boy”:
Walker and Shipman (1996).
Homo erectus
in general: Antón (2003). Comparison to habilines: Haeusler and McHenry (2004), Wood and Collard (1999). I assume that australopithecines and habilines were all sufficiently good climbers to sleep in trees, following Hunt (1991). Although that appears to be the majority view, Ward (2002) is cautious, suggesting that we cannot be sure how well
Australopithecus afarensis
climbed. However, it seems inconceivable that australopithecines slept on the ground.
101
Modern hunter-gatherers are safer in camp at night:
Kaplan et al. (2000).
102
natural selection rapidly favored the anatomical changes that facilitated long-distance locomotion:
Haeusler and McHenry (2004) argue that habilines had long legs (as well as an upper body adapted to climbing). There are only two specimens of
habilis
with sufficient postcranial remains to reconstruct leg lengths, so this is still contested ground. If they are right, the problem of where habilines slept is more complicated than my assumption that they slept in trees.
Five: Brain Foods
105
Blaise Pascal:
Pascal’s
Pensées
, 1670.
106
Richard Alexander argues:
Alexander (1990).
106
Death rates from these interactions among chimpanzees are similar:
Wrangham et al. (2006).
107
Species of primates with larger brains are more intelligent:
Deaner et al. (2007).
107
but they show no overall tendency to have larger ranges:
Dunbar (1998).
107
Robin Dunbar found:
Shultz and Dunbar (2007).
108
the crow family have many of the social abilities of primates:
Cnotka et al. (2008).
108
Bottlenose dolphins form particularly complex and changeable alliances:
Connor (2007).
108
Spotted hyenas live in large groups:
Carl Zimmer,
New York Times,
March 4, 2008. See also Holekamp et al. (2007).
108
“cerebral ganglia of extraordinary dimensions”:
Darwin (1871 [2006]), p. 859.
108
the social brain hypothesis:
Dunbar (1998), Byrne and Bates (2007).
109
In 1995 Leslie Aiello and Peter Wheeler proposed:
Aiello and Wheeler (1995).
110
genes that are responsible for energy metabolism show increased expression:
Khaitovich et al. (2008).
113
The idea became known as the expensive tissue hypothesis:
Fish and Lockwood (2003) supported Aiello and Wheeler’s proposal by showing that brain size is related to diet quality in primates. Hladik et al. (1999) suggest that other body parts are also reduced in size to compensate for large brains.
113
An elephant-nosed mormyrid fish:
Kaufman (2006).
113
Birds . . . grow bigger wing muscles:
Isler and van Schaik (2006). They suggest that in human evolution, cheaper locomotion might likewise have enabled brains to enlarge.