White-handed gibbons

White-handed gibbons are forest-dwelling small apes. They have long arms, which help them swing from tree branch to tree branch as they travel. They are bipedal and walk upright on the ground or across tree branches. These gibbons are in Khao Yai National Park in Thailand. (Photo provided)

April 28, 2017

Scholar reflects on three decades of field research

by Andrea Hahn

CARBONDALE, Ill. – After nearly 30 years, they seem to recognize his footsteps and his voice. 

When Ulrich H. Reichard, associate professor of anthropology at Southern Illinois University Carbondale, goes into Thailand’s Khao Yai National Park rainforest alone, the family group of gibbons he’s been studying since 1989 go about their business and ignore him. For a researcher in the field, it’s good to be ignored. When Reichard brings along someone else, perhaps a student researcher, the gibbons initially draw back, showing caution. 

“When I bring someone new, I put a hand on the person or stand physically close so the gibbons recognize that person as a sort of companion and not threatening,” he said. “Other researchers have noticed similar behavior. We have to be careful not to anthropomorphize, to give human personalities to gibbons. As scientists, we can’t make assumptions about behavior. But they do seem to recognize me.” 

Justin D’Agostino, a Fulbright Scholar, is a Reichard advisee, and will use his Fulbright scholarship to study siamang, a large gibbon species, in Indonesia beginning in September. Florian Trébouet, a doctoral student, is currently in Thailand studying, not gibbons but stump-tailed macaques, a study he began in 2009 and continues with Reichard’s advisement. Reichard said sometimes students find field research intimidating once they realize how much more difficult and uncertain it is than laboratory research. However, the rewards, he said, are incalculable. 

“I find that the animals I’ve been studying so long mean a lot to me,” he said. “There is a happiness I only experience in the field, I’m happy to be there.” 

Of course, it’s not just happiness that brings him back to Khao Yai. It’s research, some of it grant-funded.  Reichard has recently put some of what he’s learned during the years into a new book, “Evolution of Gibbons and Siamang: Phylogeny, Morphology, and Cognition.” The book is available from Springer Nature, an academic publisher of books in the sciences. 

Gibbons are members of the ape family, but as small apes they don’t get as much attention as the “great apes” – the gorilla, orangutan, bonobo and chimpanzee. There are 20 species of gibbon, a wealth of species diversity not available in the great apes. That’s one reason he studies them, Reichard said. Another reason is that he listened to his adviser, Professor Volker Sommer from UCL London.   

“I had absolute trust in my adviser,” he said. “He helped set me up with contacts in Thailand so I could study white-handed gibbons and he told me it was something I could do, something that would work as a source of research for a long time. He was right.” 

So every year since 1989, almost without fail, he’s spent approximately three weeks during the summer with the gibbons, often paying for his research time and travel out of his own pocket by teaching extra classes. What are some of the things he’s learned? 

Gibbons sing. They are much more vocal than other apes. Their songs are often male and female duets, a sort of antiphone, or alternating voice duet. It seems to be a ritual that may define their territory and strengthen their bond as a mated couple. But it might also be a bit competitive. Younger females sing more difficult songs, Reichard said, while older gibbon females sing more simply. The vocalization, which requires energy and carries for as much as a kilometer in the forest, may be a show of strength or reproductive desirability. 

He's also found that gibbons, thought to be monogamous, are known to trade in old partners for newer, apparently stronger, mates. “We don’t know exactly what causes that,” Reichard said. “When a young gibbon is ready to mate, opportunity has a lot to do with what is available. It might be that when a new opportunity presents itself, younger gibbons may take advantage of it.” 

Much of Reichard’s research is evolution oriented. Gibbons occupy an important but somewhat mysterious place in the evolution of human beings. Though we have a common ancestor many millennia ago, gibbons were the first ape to branch off the hominoid tree. As such, they are not always included in evolutionary studies the way the great apes, who are closer to humans, are. Reichard said it’s time to bring the gibbon back into the human evolutionary fold. 

Reichard has also studied gibbon locomotion. While they are climbers, they travel mainly by brachiation -- swinging from tree limb to tree limb with an arm over arm motion. When they are on the ground, they walk bipedal and upright for short distances. The great apes, however, are mostly “knuckle-walkers” – they sit upright but mostly move in a four-limbs-on-the-ground fashion. There is a debate among anthropologists and other scientists about the place of brachiation in human evolution. Reichard believes the bipedal nature of brachiation qualifies gibbons to remain in the evolutionary discussion. 

The argument for excluding gibbons fairly early in the human evolution process has to do with their size – specifically brain size. Reichard, and those who agree that gibbons should not be discounted too early in the human evolutionary timeline, argue that absolute brain size is less important that relative brain size – that while the gibbon is smaller than chimpanzees and other great apes, its relative cognitive ability renders it important for the study of human evolution. 

“They are not ‘dumb dwarf apes’,” Reichard said. “Other factors than a failure to evolve cognitively account for their size.” Other factors include gibbon populations existing in isolated microclimates in the Miocene epoch that affected them differently even though great ape species existed nearby and do not show the same climate-based morphological, or physical, changes. 

The answer, Reichard suspects, is in paleo-primatology – the study of the primate fossil record. 

“I’ve always been interested in gibbon evolution,” Reichard said. “I’ve wanted to go in that direction as the next logical step in my academic career. I know gibbons in a way few do – I don’t mean to exaggerate but there aren’t many scientists who’ve been in the field for such a long time over the years. As for evolution, we still have many questions about our common ancestor with the apes. The gibbon has played a role and we need to include them in the discussion.” 

Ulrich Reichard is available to discuss white-handed gibbons or topics in primate evolution. Contact him at ureich@siu.edu