Lecture at Rutgers discusses importance of pelvis in studying human evolution

A curator from the American Museum of Natural History came to Rutgers last Friday to discuss the importance of hips, particularly the pelvis, in answering larger questions in the field of paleoanthropology. 

The event, which is part of a series in the Department of Anthropology, was titled “Hips in Human Evolution” and featured Dr. Ashley Hammond, a paleoanthropologist who has been working with the American Museum of Natural History since last year. 

“I can use hips to get at some of the bigger questions in anthropology … so bigger questions such as where do we come from, when did major evolutionary transitions occur and what makes humans special,” Hammond said to start off the lecture. 

Focusing on what made humans special, she said modern humans had a relatively large brain size, made and used tools and were able to interact collaboratively toward common goals. These features, though, were not present in the earliest hominids, which refers to a family of primates that includes the great apes and humans.

Instead, both ancient hominids and modern humans were universally identified by physical features related to bipedality, or ability to walk upright on two legs. Hammond said bipedality was what changed how people moved in the landscape, freeing up their hands so that they could do other tasks. 

She then referred to Lucy, the skeleton of one of the earliest human ancestors found by paleoanthropologists. While the evidence for bipedality in hominids like Lucy, who lived several millions years ago, were more nuanced, Hammond said the pelvis was suggestive of the trait.

“It seems that the pelvis is one of the first parts of the body that really reflects an adaptation for being bipedal,” she said. 

Ancient primates had ilia, which is one of the main bones forming the upper part of the pelvis, which were flatter and had a different orientation than more modern hominids, whose ilia allowed them to walk more efficiently on two legs. 

Hammond said the pelvis also revealed details about geographic variation and where ancestors were derived from. For instance, those who lived closer to the equator have narrower pelvises and torsos than those who lived in the poles. 

The pelvis was also a way to differentiate between genders, especially since females had to give birth, she said. This was significant in determining the gender of Omo-1, which is the name of the skeletal remains of an early modern human found 40 years ago in Omo Kibish, an archaeological site in Ethiopia.

In the early 2000’s, other paleoanthropologists returned to the site. They were able to find new fossils, with some possibly belonging to Omo-1. The centerpiece of the findings was a partial pelvic bone, because pelvises tend to not preserve very well, Hammond said. 

Omo-1 had historically been assumed to a male because its skeleton had been so large. Based on the shape of the sciatic notch, or indent in the ilium, Omo-1 turned out to actually be a female. Hammond said females tend to have a more open notch, and Omo-1’s sciatic notch was in the range of modern human females. 

“This was contrary to pretty much everything we had assumed about this skeleton in the 40 years beforehand,” she said.

The newly discovered pelvic bone also revealed that Omo-1 may have even had children in her lifetime, due to a distinct groove in the bone that previous researchers have observed in many women who have given birth, Hammond said.

She then spoke about her own experience doing fieldwork, describing her experience with fossils from Eritrea, a country in East Africa. Using data analysis, Hammond compared the pelvises she found in that region compared to other hominids and hominins from different regions and time periods. She said the goal of that work was to show the range of variation between living and fossil hominins.

She ended the lecture by giving a preview of the work she planned on doing in the future regarding paleoanthropology. In order to better characterize locomotive diversity, she hopes to reconstruct the shape of the pelvis and gather new fossils. 

“The bigger question for me is what led to the origins of bipedal function. It’s great that we can characterize the diversity, but how did we get here to begin with?” she said.