45
years
Estimated upper
end of chimp life
span in the wild
60
years
Estimated upper
end of chimp life
span in captivity
Chimps may sense others’ deaths
Apes can react in intriguing ways when their companions die
Anderson says it may be more humane
to allow elderly apes to die among com-
panions in research facilities and zoos,
rather than isolating them for treatment
or euthanasia.
In the wild, chimps’ reactions to a
death vary greatly from one individual to
another, much as in people, says Elizabeth
Lonsdorf of Chicago’s Lincoln Park Zoo.
Old and sick chimps often
find sheltered spots to die
alone or are taken by preda-
tors, with the group resuming
its daily foraging. “We don’t
know yet if chimps can grieve
for the loss of a group mem-
ber,” Lonsdorf says.
Uncertainty also sur-
rounds the intentions of two
female chimps that literally
wouldn’t let go of infants that died of
infections in 2003, as described in another
study. These chimps inhabited forests
surrounding Bossou, Guinea. One, the
mother of several other chimps, carried
her 1-year-old on her back while foraging
for 68 days. The other, a first-time mother,
“We don’t
know yet
if chimps
can grieve
for the loss
of a group
member.”
By Bruce Bower
Pansy the chimpanzee died surrounded
by friends and family who cared for her as
best they could and reacted to her demise
with silent somberness. Pansy’s story,
along with stories of two
mothers unable to let go of
their deceased infants, raises
the possibility that chimpanzees know when a companion has died and realize
that it will never return, two
studies report in the April 27
Current Biology.
“Chimpanzees may have
greater awareness of the
finality of death than has previously
been believed,” says James Anderson, a
psychologist at the University of Stirling
in Scotland who studied Pansy’s death.
ELIZABE TH LONSDORF
Pansy’s case gives a first glimpse of how
chimps respond to the natural deaths of
companions, he says. Video cameras in an
indoor enclosure at a safari park recorded
activity before and after Pansy died.
In the days before Pansy’s demise
three adult chimps, including her daughter, groomed her regularly. Grooming
increased as Pansy’s breathing became
labored in the 10 minutes before death.
After she died, a male pulled at Pansy’s
arm and tried to open her mouth. He
charged in an aggressive display, pounded
on Pansy’s body and then ran off.
The next day, the three chimps watched
silently as keepers removed the body. The
chimps avoided sleeping on Pansy’s deathbed for five days and, for a few weeks, were
less active and ate less than usual.
“These incidents strengthen the inference that apes have some sort of conception of death,” says William McGrew of
the University of Cambridge in England.
carried her 2-year-old in the same way for
19 days. Then the bodies were abandoned.
In both instances, tropical weather
dried and preserved the corpses in a natural mummification process. Mothers
groomed the dead infants’ bodies. Over
time, mothers increasingly let other group
members handle and play with the bodies.
Dora Biro of the University of Oxford
in England, who led the study, is cautious
about interpreting the behavior as reflect-
ing an awareness of death. “These moth-
ers understood that there was something
unusual about their infants,” Biro says.
“But whether for them that indicated that
the infants would never come back to life
remains a fascinating open question.”
Ape mothers’ refusal to let go of dead
infants makes evolutionary sense, says
primatologist Frans de Waal of Emory
University in Atlanta. Close emotional
ties to one’s youngster prevent chimp
mothers from prematurely abandoning
sick and near-dead infants, in his view.
“Chimpanzees may know something of
someone else’s mortality, but we have no
way of knowing whether they understand
their own mortality,” de Waal remarks.
Some young dinos sported a look totally unlike their
elders, a new study shows. Feathered dinosaurs,
like modern birds, may have molted as they grew,
says Xing Xu of the Institute of Vertebrate Paleontology
and Paleoanthropology in Beijing. Xu and colleagues
discovered an age-related shift in plumage in two fossil
specimens of Similicaudipteryx, which lived in what is
now China about 125 million years ago, the team
reports in the April 29 Nature. While both fossils are
juveniles, the larger and presumably more mature
of the two— a dinosaur with a body about the
size of a goose —had long feathers on the
forelimbs and tail that look like modern
bird feathers. But in the smaller pigeon-sized creature, the feathers on the forelimbs and tail look modern only near their tips.
Closer to the body, those feathers have a ribbonlike shape but no central shaft. Unlike today’s birds, these dinosaurs changed the basic structure of their feathers during adolescence, Xu says. — Sid Perkins
Dino feather shift
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May 22, 2010 | SCIENCE NEWS | 9
