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[Carrie McLaren <stay.free AT verizon.net>]

The Daily Yomiuri (Tokyo)

February 9, 2003 Sunday

Chimp gets snip to stop crossbreeding Alpha ape in Tama Zoo given 
vasectomy when study shows 'primate purity' at risk

A male alpha chimpanzee at the Tama Zoological Park in Hino, western 
Tokyo, was given a vasectomy this month to prevent further 
crossbreeding among species in response to a nationwide campaign to 
maintain the purity of the nation's primates.

"I felt sorry for him, but there was no other way," said Koichiro 
Yoshihara, the 57-year-old head zookeeper.

The decision was made by the Japan Zoo Aquarium Association, which 
discovered more than 10 percent of chimpanzees at the nation's 
zoological facilities were the product of crossbreeding. In October 
2002, the association called on zoos to prevent further crossbreeding 
by using contraceptives or keeping different species in separate 
compartments. Kenta, a 22-year-old male chimpanzee, was operated on 
for the second time in January, after an initial procedure in May. 
His age is equivalent to the early 30s in a human.

The decision followed a report by Saga Medical School Prof. Kenichi 
Shinoda and other researchers who performed DNA analysis on 373 
chimpanzees at 57 facilities across the nation, the country's first 
such survey.

The researchers concluded in autumn 2001 that a considerable 
proportion of chimpanzees in Japan were being kept with other 
species, causing crossbreeding among species native to eastern, 
western and central Africa that would not take place under natural 
circumstances.

The study's results shocked researchers at the Japan Zoo Aquarium 
Association, who found that 65.1 percent of the nation's chimpanzees 
were descended from a western African species while 3.5 percent came 
from an eastern African species. A central African species accounted 
for 1.1 percent of the nation's chimpanzees, while 11.5 percent were 
mixed and 16.1 were unidentifiable.

Tests performed on Kenta showed his father was a native of central 
Africa while his mother was eastern African. Kenta's facial features 
are more prominent than those of chimpanzees from other parts of 
Africa, a characteristic typical of eastern African chimps.

As Kenta is an alpha chimpanzee with many mates, the park first tried 
separating him from female chimpanzees during the mating season. 
However, this measure disrupted the chimpanzees' social hierarchy as 
it meant Kenta failed to prove his dominance by mating with several 
partners.

The park, which keeps 20 chimpanzees, the largest number in the 
nation, consequently decided to breed only the western Africa 
chimpanzees. Two female chimpanzees of mixed descent have since been 
given contraceptive pills developed for humans.

After the vasectomy, Kenta continued to occupy the sunniest spot in 
the outdoor pen and watch over his clan. He also mates with his 
partners as he did before the operation.

"Kenta is good at mediating fights among others and he's respected by 
the female chimpanzees," 39-year-old caretaker Hiroki Nagata said.

On Dec. 15, the first baby chimpanzee was born at the park since the 
policy of limiting breeding to chimpanzees of pure western African 
species was implemented. The park hopes the baby chimpanzee will grow 
up well.

Since Kenta can no longer reproduce, the park is depending for a new 
generation of chimpanzees on two males descended from the first alpha 
chimp, Joe, that have been proved to be of western African descent, 
and three female chimpanzees of the same species that arrived in the 
park last year.