are from the genus Pongo and have the
slowest growth history of any of the primate taxon.  They are distant relatives to humans within
the great apes which include chimpanzees (pan) and gorillas (Yin).  There was not much known about orangutans
until Dr. Birute Mary Galdikas became the leading authority on them.   

Dr. Birute Mary Galdikas became enamored
with apes at the young age of 5.  At 6,
she read Curious George and began an
imaginary life of a wildlife explorer (Yin). 
And even through high school she remained interested in apes. After researching
the different species she found her favorite to be the “red apes” of Asia, also
known as orangutans.  Dr.Galdikas was
fascinated with the work done by Jane Goodall with Chimpanzees and wished to do
the same with orangutans. Dr. Galdikas continued onto college where she went on
receive bachelor’s degrees in psychology and zoology and an anthropology
master’s and doctorate. 

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After all of that, Dr. Galdikas found the
funding to research her orangutans.  In
1971, she made her way to the Tanjung Putting reserve in Southwest Borneo where
she set up Camp Leakey.  It took Dr.
Galdikas months to spot an orangutan.  When
she did she had to follow it on the jungle floor while it was in the
trees.  But follow it she did and she was
relentless.  She followed it until it
stopped for the night making observations. 
She came back in the morning to continue her observations and would continue
to follow them through the thick rainforest and through waist deep swamps documenting
and inventorying every orangutan she encountered.  After four years of continuous study
in the Tanjung Puting national park, Dr. Galdikas wrote the main article for
National Geographic Magazine; bringing orangutans’ widespread public

on direct and continuous long-term observations, Dr. Galdikas was the first to
document the long interval between orangutan births.  These and other observations led to Dr.
Galdikas’ “ecological energetics hypothesis, which predicts that increased diet
quality leads to a faster rate of reproduction” (Galdikas Asbury 61).    Dr. Galdikas recorded the unique population
of orangutans around Camp Leakey.  The
analysis on this group, who are isolated from the wild population, and who are
provisioned on a daily basis, creates a group element that is freed from normal
environmental constraints.  The analysis
could tell the effects that environmental conditions may have on their
reproduction and patterns of life. 

collected during her 40 years at Camp Leakey and the surrounding forest led
Dr.Galdikas to explain and demonstrate that diet contributed to the orangutans’
age of reproduction and the time between births.  Her data was collected from 19 female
orangutans: 11 first-generation mothers and 8 second-generation mothers (Galdikas
Ashbury 62).  Dr. Galdikas started with
the approximation of ages for first-generation of wild born orangutans that
were brought into the rehabilitation programs. 
These approximations were based on teeth analysis, weight, and behavioral
observations.  The second-generation ages
were based on observation as well as the visual witnesses to births. 

ages of reproduction for the first-generation mothers was estimated and were
known for the second-generation mothers. 
The average reproduction for the orangutans at Camp Leakey was 13.3
years; with first-generation mothers at 14.2 and second generation’s mothers at
12.1 years (Galdikas Ashbury 66).  Then
they recorded 72 births among Camp Leakey’s population (Galdikas Ashbury 66).
The average first-generation mothers showed they would give birth every 5.52
years while the second-generation mothers would give birth every 5.45 years
(Galdikas Ashbury 66). Compared to the Wild Tanjung Puting population, at 7.82
years we see that the length between Camp Leakey’s birth rates were lower than
those of the wild population. 

could be explained by the environment. 
Camp Leakey’s orangutans are essentially a “control” group.  They were brought in for rehabilitation and
stayed close to camp. They were subsidized with food once a day while the wild
orangutans fended for themselves on a daily basis.  It is known that diet can affect the body and
this is no different for animals than it is for humans.  The first-generation mothers were brought in
from the wild meaning for the first part of their life they had to fend forage
for food on their own.  If food was
scare, it would affect the maturity level of the body meaning that their first
menstruation, which leads to ovulation, would have been later than those in second-generation
mothers who had more steady diets.  The
result is that second-generation mothers who have access to a more highly rich
diet matured faster than the first-generation mothers.

orangutans stay with their mothers for long periods, sometimes up to 10 years
old. Even after that they can stay close to their mothers.  There is much more that Dr. Galdikas has
learned from her study and research of the orangutans.  Orangutans are found mostly in peat swamp
forests, tropical heath forests, and mixed dipterocarp forests (Galdikas
Orangutans).  They eat fruit and a
multitude of plant material to include leaves, bark, flowers, vines and even

Galdikas goal in researching orangutans is to document orangutan life
histories.  By following these wild
animals day in and day out they were able to establish the area that the orangutans
range; their age of sexual maturity; as well as birth rates and the duration
between births.  The researchers at Camp
Leakey also studied aspects of behavior and ecology such as society patterns,
foraging patterns, and their abilities of sign language and cognition.