out in marshy areas, eating grasses and
papyrus shoots, more than 3 million years
ago, Stewart reported. Papyrus marshes
feature a lot of fish, shrimp, snails, mollusks and microalgae, which the gorge
residents also dined on. “Lake and river
margins provided high-quality food to
ancient hominids, especially pregnant
and lactating females,” Stewart says.
Some researchers argue that a few
aquatic munchfests don’t confirm that
ancient hominids across East and South
Africa fancied fish. Doubters and advocates alike await finds from more digs
along African lakeshores and riverbanks.
Coast with the most
Marean suspects that such excavations
will demonstrate that an increasing
taste for catfish and other water creatures accompanied increases in brain
size among early Homo species. Stone
Age people exploited that evolutionary
endowment at Pinnacle Point, putting
their outsized brains together to solve
the puzzle of the tides, Marean says.
Protein-rich shellfish, loaded with
omega- 3 fatty acids crucial for brain
development, led to further social inno-
vations, including a move from eating for
now to organizing seaside harvests for
later, in his opinion. If so, a sense of time
needed to plan for the future character-
ized the human species almost from its
start about 200,000 years ago.
Southern bounty the distance between a pinnacle point cave labeled 13b and
the shoreline changed over time. shellfish collection probably occurred at times
when the coast was within 10 kilometers (highlighted below), though the
harvest probably changed with sea level.
Current coastline
Close coastline approaches
PP13B
PP13B
121,000–123,000 years ago
102,500 years ago
95,000–98,000 years ago
167,000 years ago
and hunted inland game until the moon
issued a call to the sea, Marean proposed
at the anthropology meeting. When the
sun and moon align, their combined
gravitational forces cause daily tides to
spring back and forth from extremely
low to extremely high levels. Such spring
tides, a twice-monthly effect that has
nothing to do with the seasons, correspond to full and new moons.
During spring tides, low tides advance
by 50 minutes each day. Fishers and
other coastal devotees today consult
printed tide schedules or programmed
watches to coordinate activities with
daily tidal rhythms. Pinnacle Point’s
Stone Age crowd informally estimated
each day’s prime time for shellfish collecting, Marean suggests.
Access to shellfish wasn’t always available during the Stone Age, though. Climate and environmental records indicate
that South Africa’s coastline repeatedly
advanced and retreated between 195,000
and 123,000 years ago. Thanks to a gently
sloping continental shelf off much of the
coast, as much as 95 kilometers of land
was exposed when sea levels retreated
during that period, Marean and his colleagues estimate.
Pinnacle Point attracted human visitors when its caves lay within about a
day’s walk of the sea, the scientists assert.
This off-and-on shoreline access over
tens of thousands of years was enough to
trigger big lifestyle changes. “Organizing
foraging activities around a complicated
system of tidal timing had a trickle-down
impact on social life,” Marean says.
Abundant shellfish and geophytes
made foragers less nomadic, increased
birthrates and reduced infant death
rates, Marean suggests. Burgeoning
Pinnacle Point communities adopted
symbolic and ritual behaviors, as well
as advanced toolmaking techniques, to
express social identities.
Tide tracking’s domino effect on mental and social life may have given modern
humans a survival advantage when they
met European Neandertals after leaving
Africa. Caves overlooking the Mediterranean Sea in southwestern Europe contain remains of fish, seals and dolphins,
africa map: geoatlas/graphi-ogre, adapted by janel kiley; receding shoreline map: a. jerardino and c. marean/JOURNAL
OF HUMAN EVOLUTION 2010, adapted by janel kiley
www.sciencenews.org
