MKB: One of the things that really stood out to me from your new documentary was the way the narrative associated tool making and tool use with an important step in non-humans becoming humans. How does that idea work with all that we now know about the many, many other animals who use tools. It’s not even just primates, right?
RL: It’s quite subtle. We know birds use tools and chimps and insects and lots of mammals. But to take a block of very hard stone and to take another stone and fashion an object from it, that’s something different. You have to “see within” the stone to know what you’re fashioning before you fashion it. You have to project an idea. That’s a step that no other tool maker uses. It’s an almost soft science definition but I can see a fundamental difference.
ML: I’d agree. Kanzi is a chimp that humans tried to teach to make stone tools. But his hands were simply the wrong shape. They don’t have the precision of grip we have and they have less flexible grip. It wouldn’t have been possible for Kanzi to make a tool as professionally as our ancestors did. We haven’t found tools older than 2.5 million years old. I’m sure that’s not the last word on this. There might be ones found that are older, but as you go back, the hand then becomes less and less flexible. The limiting factor would be the morphology of the hand. It’s more that and less the morphology of the brain, in my opinion. This aspect of being human very much depends on hand flexibility.
MKB: Meave, your team found the skull of Kenyanthropus platyops—a 3 million year old hominin—at Lake Turkana in 1999. (Other scientists argue that this skull doesn’t represent a new genus, but is rather a species of Australopithecus.) Why do we find so many skulls and skull fragments? Shouldn’t there be equal quantities of other ancient hominin bones?
ML: We do find more skulls than you’d expect. I think it has to do with the size of the brain, or rather the size of the actual skull. Other remains can get chewed up by carnivores. They aren’t as complete. But the skulls we do find in greater number than you might expect. Maybe it’s becuase carnivores couldn’t get their mouths around the skull and cruch it up, because the brain was so big. I’m speculating, but when you get back to something like Lucy, you don’t find more skulls than other bones, maybe because the brain was smaller and the carnivores were bigger. We do find other peices but they’re usually pretty fragmentary. And we’re missing lower jaws a lot, because those can be chewed up. Monkeys are another good example. There are fewer fossil monkey skulls as complete as hominid skulls, and that’s even though we find far more monkey specimens.
MKB: Richard, you grew up in the field, doing fieldwork alongside your parents. You and Meave both raised your daughter in the field. What is that experience like? Why do you think that paleontology has become this very family-oriented job for the Leakeys in a way that other industries just aren’t?
RL: If you have an opportunity to be involved in fieldwork it’s hugely exciting and rewarding. You’re out in the open in nature, unbothered by emails and telephones. And once you enjoy fieldwork, paleontology is one of the professions where you can devote a lot of time to that. I think that’s what draws you back into it as an adult. as A result of my childhood is that I always had a natural curiosity about origins, extinction, and evolution. It’s a natural part of my life. It’s not the only thing that interests me, obviously, but fully understanding why we are what we are—I think it adds to the whole human experience.
ML: You also have to understand that we’re only three months of the year in the field and those months tend to fall within school holidays. Our children were in the field with us the entire time, from the time they were babies. They were in the camp or in the base. We’d take them out now and again and they’d get very excited about finding things. When they were older, they were able to start helping in camp, picking out bone fragments. The result of all of that exposure is that they say they definitely won’t get into the subject as adults. Of course, Louise said exactly that, but now she’s fully involved. Our other daughter said no and kept her word.
Image 1: The Leakey family excavating a pelorovis skull. Our human ancestors once feasted on these ancient bovids (akin to cows). Courtesy National Geographic Television.
Image 2: Kenya 1987 Lake Turkana woman and dogs, a Creative Commons Attribution Share-Alike (2.0) image from wfeiden’s photostream.
Image 3: Meave Leakey. Courtesy National Geographic Television.