What is the common trait linking Turkana Boy, a 1.5-million-year-old hominid with a nearly human-sized brain, to Richard Leakey, the legendary leader of the team of scientists who found the bones in the Turkana Basin of Kenya?
To get to the answer, you have to understand the long quest by the Leakey family to probe the origins of humanity. That story is the subject of a National Geographic documentary, "Bones of Turkana," airing tomorrow at 10 p.m. on WNET/13.
Leakey, his wife, Meave, and daughter, Louise, lead the Turkana Basin Institute. Its headquarters are at Stony Brook University, where they serve on the anthropology faculty. But they spend most of their time in Kenya, at the world's largest permanent desert lake.
Leakey's parents, Louis and Mary, were leaders in the dawning understanding that our species, homo sapiens, arose from Africa. As a young man, Richard was reluctant to take up his parents' digging life. Then he did field work for his father in Ethiopia, and he was hooked.
"But even though I was interested, I wanted my own patch," he says in the film. "And it just happened that I flew over Lake Turkana and realized that nobody had looked there before." That vast lake, the most saline of Africa's big lakes, and its desert surroundings became the patch he had wanted.
In the decades since, Leakey, 67, has become a lion in two fields: searching the origins of our species and protecting wildlife in Kenya. This new film focuses primarily on Turkana. Producer-director-writer John Heminway had known Leakey since making an earlier documentary in 1971, and he had ample footage of the young paleoanthropologist. In "Bones of Turkana," the old images are juxtaposed with extensive interviews with Leakey today.
The Leakey clan interrogates old bones for clues to the development of traits that moved us beyond our ancestors: walking on two feet, making tools and learning to talk. Among their finds: the earliest biped, from 4.2 million years ago.
But there was a time when Leakey says he hit a midlife crisis. So he took a job leading the Kenya Wildlife Service. There, he fought against rampant poaching of elephants for their ivory. His coup was a 1989 bonfire that burned vast amounts of seized ivory, creating immense publicity for the conservation cause.
"That was the first moment when the world paid attention to what was happening with elephants," said co-producer Katie Carpenter.
But his outspokenness made enemies, who sent him death threats. And Leakey thinks they cost him his legs. Piloting his own plane, he left with a full tank of gas, and 10 minutes later, it was empty. In the emergency landing, the engine detached and crushed his legs.
His career in wildlife and government service was important, but Turkana is his life. All those years there under the glaring sun weathered his face. And the amputation of his legs gave him a deep kinship with Turkana Boy.
As he studied the remains, Leakey realized that the boy had bone disease and a deformed spine. So he needed a lot of help to survive. That led to Leakey's finding, based on the fossil evidence, of another core human trait: compassion.
"The fact that he was able to deduce this from Turkana Boy's skeleton was really exciting," Carpenter said.
There's a lot to like about this film: gorgeous cinematography, music by Paul Simon, clever computer-generated images, a compelling family saga. At the top of the list, despite all the gory evidence to the contrary in today's violent and often ruthless world, is the scientific theory that compassion is bred into our bones.
Bob Keeler is a member of the Newsday editorial board.