University of Calgary expert assist give history of early apes a fresh perspective

AUniversity of Calgary researcher is helping to rewrite the (pre-)history books when it comes to how and where apes lived in eastern Africa millions of years ago.

A team of international researchers, Research on East African Catarrhine and Hominoid Evolution (REACHE), have spent the last decade researching the ecosystems in eastern Africa in the early Miocene time period (approximately 16 to 23 million years ago) and how apes lived within them. These research efforts have led to the recent publishing of two studies in the journal, Science.

Up until now, scientists believed apes back then all lived in forested areas with large tree canopies. However, REACHE has now discovered that at least some lived in what could be described as wooded grasslands, with sparse trees and the dominant ground cover being C4 grass, which is a type of warm-season grass.

“At our [research] sites dating between 21 and 16 million years ago, we see a variety of habitats present, including some that are surprisingly open — and, when I say open, I mean that they would still have trees, but that the trees are relatively sparse,” says team member Dr. Susanne Cote, PhD, an associate professor with UCalgary’s Department of Anthropology and Archaeology.

“We didn’t expect that; that’s a surprising environment to be finding a lot of apes living in … generally, the conventional knowledge on this has been that grassland environments don’t really start to dominate eastern-African landscapes until 10 million years ago, and our research pushes that back to over 20 million years ago.”

Susanne Cote
Susanne Cote has made the journey to Africa almost every year since 2001 to study fossil collections of primates and other mammals, as well as participate in paleontological fieldwork.

Samantha Lafleur, Advancement

REACHE also uncovered what is considered the oldest currently known ape species, Morotopithecus, named after Moroto, Uganda, location of the team’s oldest research site, which is an estimated 21 million years old.

“It’s special not only because it’s old, but also because while we don’t have a full skeleton of Morotopithecus, we have material from the face, the teeth, the femur and the vertebrae,” says Cote. “Even just these small pieces are enough to demonstrate that it is unique from other Miocene apes from this part of the world in that it seems to have a body plan very similar to modern apes.”

This means Morotopithecus was very good at vertical climbing and moving through trees. The team originally believed this adaptation was a result of it living in forested areas, but then they discovered the area was more thinly treed than expected. This suggested that the trait was more likely a result of the species trying to find ways to stay arboreal in a thinning branch canopy that made it harder to jump from tree to tree. Therefore, Morotopithecus likely spent much more of its time climbing up and down trees than originally thought.

Cote says one of her biggest highlights of contributing to this research was working with her fellow team members.

“The lead authors on both papers are good friends of mine; we’ve been working together a long time,” she says. “The field work itself is really fun. We have strong support from the National Museum of Kenya and the Uganda Museum and many of the co-authors on the paper are staff members, research scientists, curators at those institutions.

“For me, getting to go back year after year to these places, to work at the museums with the fossil collections, to go out in the field and collect new fossils and new geological data, has been really a joy.”

Cote says the team still returns to the area yearly, and that will be no different this year. She says they are focused on finding more ape fossils in hopes of learning more about our evolutionary history and the evolutionary history of our close relatives. They are also beginning to move into slightly younger sites dating back around 13 million years, a period relatively understudied in Africa, but important for ape evolution.