LIFE & EVOLUTION
set nursing record
Babies can suckle for more
than 8 years, tooth tests show
MATTER & ENERGY
Sci-fi technology could go quantum
In theory, ‘matter wave’ tractor beam would pull in atoms
BY SUSAN MILIUS
The supermoms of the mammal world are
big, shy redheads. Studying growth layers
in orangutan teeth shows that mothers
can nurse their youngsters for eight-plus
years, a record for wild mammals.
Teeth from a museum specimen of
a young Bornean orangutan (Pongo
pygmaeus) don’t show signs of weaning
until 8.1 years of age. And a Sumatran
orangutan (P. abelii ) was still nursing
during the few months before it was
killed at 8.8 years, researchers report
May 17 in Science Advances.
These tests also show that orangutan
BY EMILY CONOVER
The wavelike properties of quantum
matter could lead to a scaled-down
version of Star Trek technology. A new
kind of tractor beam could use a beam of
particles to reel in atoms or molecules,
physicists propose in the May 5 Physical
Scientists have created tractor beams
using light or sound waves, which can
pull small particles a few millimeters
or centimeters (SN: 11/15/14, p. 16). But
“the idea of doing this with matter waves
youngsters periodically start to taper
off their dependence on their mother’s
milk and then, perhaps if solid food
grows scarce, go back to what looks like
an all-mom diet. Such nursing cycles
aren’t known in other wild mammals,
says study coauthor Tanya Smith, an
evolutionary anthropologist at Griffith
University in Nathan, Australia.
Weaning information for orangutans
has been sparse. Field biologists’ best
efforts to track weaning in Bornean
orangutans with known birthdays had
pegged 7. 5 years as the longest probable
nursing time, Smith says. She knows of
no such reports for Sumatra’s orangutans.
Orangutans don’t make weaning easy
to detect, says Serge Wich of Liverpool
John Moores University in England,
who was not involved in the study. He
started watching the apes in 1993, and
points out that “lactating happens very
high up in trees, so we are always under
a bit of an awkward angle to observe.
Also, they’re quite furry.” Determining
whether an infant is suckling or just cuddling is not an exact science.
For more accurate dating, Smith and
colleagues turned to teeth. Primate
teeth grow a distinct microscopic layer
every day, starting before birth. Babies
grow bones and teeth using milk calcium, which moms pull from their own
skeletons. A similar element, barium,
is really groovy,” says physicist David
Grier of New York University.
Sound or light waves can pull small
particles under carefully controlled
conditions. For certain types of beams,
waves can scatter forward off of a particle, pushing the particle back toward
the source of the beam due to the law of
conservation of momentum.
“We have used a very similar reasoning here,” says study coauthor Andrey
Novitsky, a physicist at the Technical University of Denmark in Kongens Lyngby.
By analyzing tooth chemistry, scientists estimated the age of weaning for wild orangutans.
hitchhikes along and ends up in bones
and teeth, too. “Mothers dissolve parts
of themselves to feed their children,” as
Smith puts it. Greater concentrations
of barium in a tooth layer mark a time
when the tooth was being built up with
a greater proportion of mother’s milk.
To read the history of mother’s milk,
Smith and colleagues tracked barium in
molars from four immature specimens,
two of each orangutan species, which
were preserved in museum collections.
The teeth came from decades ago when
collectors “went around randomly shooting endangered species,” Smith says.
Now, Bornean and Sumatran orangutans rank as critically endangered. A
fever of logging and oil palm planting
is eating away their forests, and the pet
trade rewards hunters who shoot a mom
to bag a baby to sell. Neither species had
lush resources to begin with, as the apes
evolved in forests with booms and long
busts in food supplies. Prolonged nursing of young may be part of their slow-lane accommodation to uncertainty and
scarcity in their environment.
Researchers debate whether some
similar uncertainty shaped human evolution. Among apes, the human species
evolved a “stretched-out” childhood, but
with different pacing from that of orangutans, Smith says. “Studying our cousins
puts our own history in context.” s
But rather than light or sound, “we have
something more elusive” — matter waves.
In quantum mechanics, particles
behave like waves, spread out so that
they have no definite position. Quantum
waves represent the probability that a
particle will be found in a particular spot
if its location is measured. Novitsky and
colleagues calculated that such matter
waves could produce a pulling effect
similar to light or sound waves.
Matter wave tractor beams could be
made with beams of electrons, Novitsky
says. Such beams could provide new ways
of manipulating matter on small scales.
These tractor beams could be used to separate mixtures of atoms or ions, for example, reeling in one type but not another. s