A Theory of Human Life History Evolution - Radical Anthropology ...

ARTICLE Evolutionary Anthropology 169
cut across the palm leaf stalks. Girls
take longer to extract the starchy fiber
from the trunk of a downed palm because
they do not know how to cut
open a window nor how most efficiently
to pound the fiber away from
the hard outer trunk wood. When
these components activities of palm
extraction are combined, Ache women
do not reach peak return rates until
their early 20s (Fig. 9).
Supporting data are also available
from other groups. !Kung (Ju/’hoansi)
children crack mongongo nuts at a
much slower rate than adults do. 28
Bock 29 has shown that nut-cracking
rates among the neighboring Hambukushu
do not peak until about age
Figure 7. All Ache data, including timed counts of fruits acquired per minute, were analyzed
for each age category. The mean plotted is the average from each independent monitored
count for a given age class of acquirers. Fruits other than those that are simply
collected from the ground or low branches were not included in the analyses. Y values are
plotted at the mean age for each class analyzed.
servations of Ache fruit collection
show that foragers generally acquire
the maximum observed rate by about
age 20 (Fig. 7). Some fruits (for example,
pretylla) that are simply picked
from the ground are collected by children
as young as one-and-a-half to
three years at 30% of the adult maximum
rate. For fruits such as vijulla,
which must be picked off branches,
children do not reach 50% of the adult
maximum rate until age 15 (Fig. 7). As
mentioned earlier, fruit collection by
the Hiwi (Fig. 8), unlike that done others,
is labor-intensive and requires
travel to distant food sites. Both males
and females reach maximum return
rates by about age 25.
Hadza data also show competent
fruit collection by children. The
Kongoro berry collection rate of
young married girls is equal to the
adult women’s rate. 6 Baobab collecting
and processing seems to reach
50% of the adult rate by about age
12. 14 Baobabs are an interesting
food resource because they are both
collected and extracted. While they
can easily be picked off the ground,
much more food energy is obtained
when the pith is extracted with pounding
and water. Young children do not
practice these activities, whereas older
children do. 14
In contrast to the hourly acquisition
rate of fruits, that of extracted resources
often increases through early
adulthood as foragers acquire necessary
skills. Data on Hiwi women show
that their root-acquisition rates do not
become asymptotic until the women
are about age 35 to 45 years (Fig. 8).
The root-acquisition rate of 10-yearold
girls is only 15% of the adult maximum.
For Hiwi males, the honey-extraction
rates peak at about age 25.
Again, the extraction rate of 10-yearolds
is less than 10% of the adult maximum.
Experiments done with Ache
women and girls clearly show that the
young adults are not capable of extracting
palm products at the rate obtained
by older Ache women (Fig. 9).
Girls take longer than women to cut
palms because they lack strength and
because they cannot judge whether a
palm will fall to the ground or get
stuck in nearby tree branches. Girls
take longer than women to extract the
growing shoot from the palm after it
is on the ground because this task requires
strength and knowing where to
Hourly return rates
provide further evidence
that important human
food resources require
long periods of learning
and skill development.
Observations of Ache
fruit collection show that
foragers generally
acquire the maximum
observed rate by about
age 20.
35. Hadza women, however, appear to
obtain maximum root-digging rates
by early adulthood, 6 perhaps because
they obtain a good deal of practice
throughout childhood 13,14 and thus
require only adult strength in order to
produce at adult rates.
Casual ethnographic observation
supports the generalization that fruit
collection is easily learned, extraction
skills require more time to develop,
and hunting is the most difficult foraging
behavior. Anthropologists working
with modern foragers often participate
in fruit collection and can
rapidly achieve aboriginal return rates.
Some types of extraction can also be