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Reichard has a new book and 30 years in the field

April 18, 2017

Gibbons hanging from tree limbAfter nearly 30 years, they seem to recognize his footsteps and his voice.

When Ulrich H. Reichard 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 says. “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.”

SIU professor Ulrich ReichardReichard 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 advisor, Professor Volker Sommer from UCL London. 

“I had absolute trust in my advisor,” he says. “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 about three weeks during the summer with the gibbons. 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 bonds as mated couples. 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 says. “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 that great apes, which are closer to humans, are. Reichard says it’s time to bring the gibbon back into the human evolutionary fold.

Reichard also has studied gibbon locomotion. While they are climbers, gibbons 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 than relative brain size – that while the gibbon is smaller than chimpanzees and other great apes, its relative cognitive ability render it important for the study of human evolution.

“They are not ‘dumb dwarf apes,’” Reichard says. “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 now 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 says. “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.”