Environmental Engineering Reference
In-Depth Information
5.5 Gathering, Hunting, and Fishing
For more than 99% of its existence the genus Homo—
beginning with Homo ergaster from Kenya's Turkana Ba-
sin 1.9-1.5 Ma ago (Wood and Collard 1999)—survived
as a simple heterotroph by gathering, hunting, and fish-
ing as an omnivorous user of basic tools without any per-
manent abodes. The genus differed from its predecessors
in several key physical features, all with profound con-
sequences for its energetics (Aiello and Wells 2002).
They included larger bodies with relatively larger brains;
smaller gut, teeth, and jaws; slower growth and delayed
maturation; and outstanding capacity for running. Larger
bodies required more energy but made thermoregulation
easier, increased mobility, and expanded prey size. Larger
brains were accommodated without higher energy con-
sumption by a smaller gut (see section 5.1). But endur-
ance running may have been more important for the
evolution of human bodies than any other adaptation
(Carrier 1984; Bramble and Lieberman 2004). Walking
cannot explain such key physical changes as extensive
springs in the leg and foot (long Achilles tendons), short
toes, enlarged heel bone, hypertrophied gluteus maxi-
mus, short forearm, tall and narrow waist, and strong spi-
nal extensor muscles and nuchal ligament that stabilize
the trunk and balance the head.
Endurance running would have been a major advan-
tage in both scavenging and hunting. Given their body
size and lack of effective weapons, it is most likely
that the earliest members of our genus were much better
scavengers than hunters (Blumenschine and Cavallo
1992). Many large predators (lions, leopards, saber-
toothed cats) left behind partially eaten carcasses. This
meat, or at least the nutritious bone marrow, could be
reached by endurance runners before it was devoured
by vultures and hyenas or by other hominids. However,
because these scavenging opportunities were often rare,
and always unpredictable, hominids could never be stra-
tegic scavengers (as vultures are), merely opportunistic
exploiters (Tappen 2001).
Weaponless runners could also chase animals to ex-
haustion, as some did even after 1900 (Heinrich 2001).
Tarahumara and Navajo ran down deer; Paiute and Na-
vajo, pronghorn antelopes; Kalahari Basarwa, duickers,
gemsbok, and during the dry season even zebras. These
fast animals could not match the human endurance, vari-
able speed, and heat dissipation that opened up a new
niche for Homo as a diurnal, hot-temperature predator.
These humans ran barefoot, and studies show that run-
ning unshod not only reduces energy costs by 4% but
causes fewer acute ankle and chronic lower leg injuries
(Warburton 2001).
The energetics of hunting improved with the introduc-
tion of weapons. Throwing spears date back as far as
380,000-400,000 years ago (Thieme 1997), predating
the emergence of early modern humans, now dated at
150,000-195,000 years ago (Trinkhaus 2005). Bows
and arrows were used from about 25,000 years ago, line
fishing from about 12,500 years ago, and nets made
from twisted fiber, hair, or thongs from about 8,000
B
.
C
.
E
. (Coles and Higgs 1969). The earliest date for the
control of fire has receded to 790,000 years ago (Goren-
Inbar et al. 2004). Cave and pit bones are used to iden-
tify a long list of animals eaten around prehistoric fires,
and isotope ratios (
13
C and
15
N) can separate plant
remains into legumes, nonleguminous C
3
species, and
C
4
varieties, and their determinations in human bone
collagen can uncover relative amounts of terrestrial and
aquatic foods in prehistoric diets (De Niro 1987). This
evidence is insufficient for energy supply calculations.
Plant remains have been preserved only infrequently,
