Biruté Galdikas

Zoology, Animals, Physiology, Metabolism

World’s foremost authority on orangutans

"I’ve always wanted to study the one primate who never left the Garden of Eden. I want to know what we left behind."

Anthropology is the study of human beings, but Galdikas studies physical anthropology, looking to our evolutionary ancestors and relatives, the great apes, to help understand the mysteries of human nature. Galdikas has been working and living in the rainforest for more than 30 years. During this time she became the co-founder of Orangutan Foundation International and other orangutan support groups all over the world. She has written articles for National Geographic, Science and other journals as well as several books on orangutans.

At any given time, about 200 orangutans live in the Orangutan Care Centre and Quarantine Galdikas set up in Kalimantan Tengah, Indonesian Borneo. The centre releases about 30 into the wild every year, but more are always coming in, found as orphans as a result of palm-oil plantation development, which is destroying the tropical rainforest at an alarming rate. Galdikas spends an increasing amount of time in conservation and activism efforts to preserve the wild rainforest where her study animals live. In 1998 she persuaded the Indonesian government to set aside 76,000 hectares as an orangutan reserve. She is currently fighting to halt the expansion of palm-oil plantations in the 400,000-hectare Tanjung Puting National Park. “Even though I’m a scientist, the animals I’m studying are going extinct so I’ve had to get involved in political activism,” says Galdikas. She believes there are only about 6,000 orangutans left in the park.

Decades of observation have resulted in many new discoveries about orangutans. “We now know they have the longest birth interval of all mammals,” says Galdikas. A female will have her first baby at the age of 15 or 16, but then an average of eight years will pass before the second baby comes. This is mostly because of the long period that a young orangutan must remain with its mother to learn how to live in the rainforest. There are many dangers and hundreds of different ways of finding and preparing food.

Galdikas and her team have contributed to veterinary medical knowledge about orangutans, including treatments for malaria, tapeworm parasites and throat-pouch infections.

Orangutan mother and baby.1. The Rain Forest

The tropical rainforest is one of the most stable natural places on the planet Earth. A huge variety of plants and animals thrives there, and nothing has changed for millions of years. This is why the common ancestor for all apes, and humans, may have been somewhat like an orangutan. Orangutans have no serious predators other than humans. Their dietary knowledge of the irregular fruiting patterns of tropical plants indicates how intelligent they are. It also explains their solitary lifestyle and the long interval between births. A big animal needs a lot of foraging territory, without too many competitors around who eat the same kinds of food.

2. Structural Brachiators

Orangutans are structural brachiators, which means they are built to swing from branches with their upper limbs, but they have become too heavy to move quickly like this. Adult orangutans are the largest tree-dwelling animals on Earth, averaging about 100 kilograms for males.

3. Food Collecting

In this photograph, a mother orangutan collects sweet habu-habu bark for her baby. This is one of over 400 types of food orangutans enjoy in the rainforest, and Galdikas has tried many of them herself. One way she has learned to spot orangutans in the dense foliage is to listen for the sound of fruit peels and pits dropping to the ground.

4. The baby is reaching for the food.

Through the repeated transfer of food between mother and baby, young orangutans learn what kinds of food are good to eat and how to eat them. They watch and imitate. They learn by trial and error. For instance, they might try eating the peel of a fruit and discover that it is too bitter. After making this error once or twice, they don’t try it again.

5. Babies

Baby orangutans cling to their mother’s fur until they are four years old. They are very dependent and remain with the mother for nine years. Females have perhaps four offspring in a lifetime. Orangutan males live solitary lives, looking for other orangutans only to mate. The orangutan’s natural lifespan is about 60 to 70 years in the wild. In zoos they normally die at around 35 years of age, but some have lived for up to 56 years in captivity.


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Galdikas would like to know the relationship of males to females in a given range of rainforest habitat. Males come and go. How far do they go when they disappear? How many females do they mate with? How far apart are the females? Over how large an area of rainforest does one single male mate, and how successful are these matings? These are all open questions.

Another thing that bothers Galdikas is the way she sees orangutan behaviour appearing in modern men and women. It’s a mystery to her why human beings who are normally social, gregarious creatures, are becoming more individualistic like orangutans. She says, “What I have learned from orangutans is that we humans must not turn our backs on our own biological heritage. Modern society promotes the ideal of the rugged individual. For men you have the Clint Eastwood persona — the Marlborough Man. For women you have single moms raising their kids alone. The ideal Western male rides into town, fights the bad guys, falls in love and then heads off into the sunset. He is strong and solitary just like an orangutan, but he represents an evolutionary dead end. Many of today’s problems are a result of abandoning our human biological roots. We must look to our distinctive gregarious human heritage; living and working in family groups and communities if we want to be successful. Otherwise we are just stressed out ‘orangutans’ in an urban setting.”

Explore Further

Biruté Galdikas and Karl Ammann, Great Ape Odyssey, Harry N. Abrams, 2005.

Biruté Galdikas, Reflections of Eden, Back Bay Books, 1996.

Biruté Galdikas, Orangutan Odyssey, Harry N. Abrams, 1999.

Biruté Galdikas, “Orangutans: Indonesia’s People of the Forest,” National Geographic, p. 444, October 1975.

Biruté Galdikas, “Living with Orangutans,” National Geographic, p. 830, June 1980.

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