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CAREFREE, ARIZ.—What does it mean to be human? A panel of anthropologists at the inaugural Origins Symposium organized by Arizona State University yesterday presented several perspectives—from genetic to cultural to environmental—on where and how the birth of our species occurred.
The weekend meeting brings together 70 leading scientists, including eight Nobel laureates, in origins studies across all disciplines, to explore major questions in their fields. Live webcasts continue today; presentations open to the public will follow on Monday.
Anthropologist Alan Rodgers of the University of Utah spoke of the new insights from genetics and how fast-evolving areas of the human genome provided new traits, such as the ability to digest milk into adulthood, contributed to survival success. “Current evidence suggests that we are a rapidly evolving species,” he added. “We have changed a lot in a few tens of thousands of years.” (An upcoming report from Scientific American will detail many of these changing regions.)
Adaptability was a key factor in our species’ emergence, agreed Don Johanson, the founding director of the Institute of Human Origins at Arizona State and discoverer of the 3.18-million-year-old fossil skeleton “Lucy.” “Our success is a combination of classical biological evolution and human cultural evolution,” he added. The influence of culture was swift and powerful. “Ten thousand years ago, at the start of the agricultural revolution, the biomass of humans was only one tenth of a percent of the entire mammalian biomass,” said Johanson. “Within just 500 generations of time, we have grown to 98 percent of mammalian biomass.”
A factor behind that fantastic growth is our unique ability to grapple with abstract concepts. “Being human means being a symbolic creature,” said Ian Tattersall, the curator for the division of Anthropology at the American Museum of Natural History in New York. “While our brains are symbolic, they’re not entirely rational,” he added, showing that this new ability was added on top of ancient systems.
Tattersall shared a striking slide of the skeletons of a Neandertal and modern human. The physical differences were clear, but when did humans arise? It was not a linear progression, as John Fleagle, a professor of anatomy at Stony Brook University, made clear. “We are a complete mosaic of features,” he said. Some of those features—such as fingernails, which appeared 54 million years ago—date to the earliest progenitors. Others, such as the wrist (10 million years ago), knee (3.5 million years ago) and our big brains (2 million to 1 million years ago) are far more recent.
Chance also played a role in the development of humans today. The work of anthropologist Curtis Marean, who is associate director of the Institute for Human Origins at Arizona State, has tracked our progenitor population to some 600 individuals trying to survive a cold period some 140,000 years ago on the coast of South Africa. The hominids benefited from a rich diet of shellfish, which enabled them to thrive. “The core who survived made a cognitive leap,” he said. The steady food supply “allowed innovations to be taught, passed on and improved.” That’s why, he concluded to appreciative chuckles from the audience, “The baseline adaptation is life on the beach.”