Fossil skulls found beneath a medieval village in the former Soviet Republic of Georgia have raised questions about the identity of the first hominids to be intercontinental travelers who set in motion the migrations that would eventually lead to human occupation of the entire planet. And G. Philip Rightmire, a BU paleoanthropologist, has been right in the middle of the monumental event.
When discoveries such as these develop, Rightmire is among the handful of experts in the world who is contacted for his expertise in identifying and studying the anatomy of new human or pre-human skulls. He has become an internationally recognized figure in the field and is regularly interviewed in national and international publications such as National Geographic, Science and the New York Times Science section.
The publicity is not without its downside. “I used to be happy to get a call from the media to explain the research,” Rightmire said. “Now it gets to be more of a burden, an obligation that goes along with the job.” The intense media interest in turn is generating potential funding. “All the publicity prompts granting agencies to sit up and take notice,” Rightmire said.
What prompted all of the attention was the discovery of three skulls and other specimens representing early Homo with an age of approximately 1.75 million years, making them the largest collection of such individuals from any one site older than around 300,000 years. In 2000, Rightmire was contacted to visit the site at Dmanisi, Georgia and offer some opinions on the new fossils.
“Nobody supposed humans this ancient would turn up anywhere in Eurasia,” Rightmire said. “The site in Georgia was a big surprise.”
Until this discovery, researchers generally believed that the first humans to leave Africa departed not much earlier than one million years ago and that they had large brains and relatively advanced stone tools that enabled them to explore unknown environments. But the numerous tools and stone objects found at the Georgian site are of an earlier, less sophisticated type. Also, the fossils suggest that the people were relatively small,” Rightmire said.
“The brain size varied from about 600 cubic centimeters to 775 cubic centimeters, about half that of a modern human. This has caused us to rethink the whole migration issue, because there’s not much in the way of a tool kit and they had a small brains.”
The new fossils also offer a rare glimpse into the diversity of a primitive human species. While we take for granted that modern humans come in all shapes and sizes, scientists know little about individual variation among our ancestors. “The findings show a single population caught in time,” Rightmire said. “Variation is to be expected in an early human group, but there are good indications that these people were generally small and lightly built.”
The discoveries were the start of an unexpected new direction in Rightmire’s research. “I was focusing on the last million years of evolution, but all of that is on the back burner now,” Rightmire said.
“Because early Homo erectus established a foothold at Dmanisi, this site and two or three others of the same age in Georgia will bear investigation.”
According to Rightmire, Georgia and other places, including eastern Turkey, have not been searched extensively before. “There is no reason people couldn’t have moved into these locations also,” Rightmire said.
“The discoveries have caused me to shift gears in terms of where I travel and what I research in the future. I plan on going back to Georgia for at least three or four years. I would have been traveling to east Africa, so it’s a shift in the direction of my research. But that’s something I’m pleased about.”
Rightmire will have sabbatical in the spring, so he may be traveling to Dmanisi then. “It’d be nicer to go back in May,” he said. “The weather in July and August, the field season there, is very dry and dusty, the worst part of the year. So I’m going to try to go back earlier.”
Scholars of human prehistory eagerly await the next finds from Dmanisi and elsewhere. Hopefully new discoveries will help untangle the branches of the human family tree to reveal the true ancestry of Homo sapiens. Whether this happens or not, it is likely that Philip Rightmire will be in the middle of the effort.