AnthroQuest
no. 34 Fall/Winter 2016
The Newsletter of The Leakey Foundation
Humans, the High Energy Ape
HERMAN PONTZER, LEAKEY FOUNDATION GRANTEE, CITY UNIVERSITY OF NEW YORK
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or over a century, paleoanthropologists have been scouring the globe for human fossils, assembling the evolutionary history of our lineage bone by bone. As Darwin predicted, the human lineage began in Africa around 6 million years ago. The earliest hominins were bipedal but otherwise quite apelike. Then, about 2 million years ago, things began to change. Brain sizes increased, tool technology became more sophisticated, teeth and diets shifted to include more meat, body size and proportions became more like An adult male gorilla. Gorillas are the largest ape, but expend less energy for their size than modern humans. Our lineage crossed humans or chimpanzees. Photo: Lincoln Park Zoo some critical, if indistinct, threshold: the dawn of the genus Homo. inevitably means reducing investment a technique borrowed from human somewhere else; trade-offs are the rule, nutrition science, to measure the The origin of our genus presents some because energy is limited. How did our calories these apes burn each day. The of the most vexing questions in human lineage escape the energetic constraints apes in our study drank a small dose evolution. Humans have the biggest limiting brain size, reproduction, of water enriched with stable, harmless brains, biggest babies, most offspring, longevity, and activity in other apes? isotopes of hydrogen and oxygen. We longest lives, and most physically mixed the water with fruit juice and demanding lifestyles (until the advent For the past six years, with support gave it as a treat. We then collected of cities, anyhow) of any living ape, from The Leakey Foundation, I’ve led urine samples every couple of days changes that are thought to have their a study tackling these questions by for two weeks to track how quickly beginnings in early Homo. Each of measuring daily energy expenditures their bodies flushed out the isotopes. these traits cost energy, calories that across all of the living apes – This allowed us to calculate each ape’s we must wrest from the environment chimpanzees, bonobos, gorillas, and daily production of carbon dioxide, and process in our cells. Evolving all orangutans. Working with zoos and providing a direct, physiological of them together seems to violate a sanctuaries around the U.S. and across measure of calories burned. This fundamental law in biology. In other the globe, my colleagues and I used approach has become the gold standard species, evolving one costly trait the “doubly labeled water” method, for measuring daily energy expenditure
The mission of The Leakey Foundation is to increase scientific knowledge, education, and public understanding of human origins, evolution, behavior, and survival.
INSIDE
Awarded Grants: Spring 2016 Cycle pages 4 & 5
[continued on page 3]
Director’s Diary: France & Germany
Million Dollar Challenge Donors
pages 6 & 7
pages 8 & 9