Over the past 7 million years, 27 human species have roamed the Earth. If that time span was graphed over 365 days, Homo sapiens are not only fashionably late to the party, but incredibly young.
“If you compress the 7 million years into a year, we show up around Christmas,” says Chip Walter, the author of “Last Ape Standing: The Seven-Million-Year Story of How and Why We Survived” (Walker & Company).
Walter speaks July 23 as a guest of Writers Live at the Oakland branch of the Carnegie Library of Pittsburgh. The event is free, but registration is required.
“Last Ape Standing,” the Shadyside resident's fourth science-oriented book, grew out of his last effort, “Thumbs, Toes, and Tears,” an exploration of the traits that make humans different from animals. The concept of that book caused Walter to start thinking about how Homo sapiens survived when so many other species, notably Neanderthals — “a really tough breed of people, and very smart” — didn't.
Part of the answer lies in neoteny, the retention of juvenile characteristics in the adult form of a species.
“We're probably the most extreme version of (neoteny) among primates,” Walter says, noting that, at birth, human and chimpanzee infants have similar physical characteristics. Chimpanzees quickly lose their youthful features and aspects, but Homo sapiens retention of youthful qualities enabled the species to survive while others died off.
“Because of our youth and because our brain is so impressionable for the first six, seven years of our life, you're going to be a much more unique individual,” Walter says. “You're going to have special ideas, and because of those ideas you're going to be more adaptable, a little more creative. ... The reason why we're the last ape standing is because we have the longest childhood and therefore are the most adaptive and creative.”
According to Walter, the first Homo sapiens emerged from a common ancestor shared with Neanderthals — Homo heidelbergensis — from 200,000 to 250,000 years ago. Around 70,000 years ago, there was a cataclysmic ice age that nearly eliminated our ancestors, with only a few hundred people surviving in a “temperate and sustaining” area at the tip of South Africa, where the Indian and Atlantic oceans met.
That Homo sapiens survived, Walter says, was “a total crap shoot.”
“We got out of the savannah (in other areas of Africa), and we should have been wiped out,” he says. “But the species managed to hang on long enough to survive. We got upright, we developed our thumbs and started making tools, found a way to cool our brains and grow them larger, and eventually we made it.”
The Homo sapiens' mastery of adaptability has served the species well. But Walter thinks another evolutionary step might be in the offing because of our success. As the world becomes more complex because of our creativity and genius, humans are increasingly inundated with information and opportunities, from 24-hour news channels to more sophisticated weaponry.
“We're in this arms race where we create more and more gadgetry to keep up with the gadgetry we create,” Walter says. “It makes our lives more difficult. ... I do feel like it's increasingly difficult to keep up. So, we have more and more gadgets to handle information faster and faster, but the human bandwidth doesn't grow that fast. The one rule of evolution is if the environment changes and the creature is no longer adaptable to the environment, guess what happens?
“The argument I make is that while Homo sapiens may not make it long term ... we may evolve into another species, cyber sapiens. We might wipe ourselves out in nuclear war or there might be plague or something like that, but assuming we don't do that, we'll just evolve into a different creature. And, at some point in time, we'll look back and say, ‘Remember those Homo sapien creatures?' ”
Rege Behe is a contributing writer for Trib Total Media.
What: Author discusses his book “Last Ape Standing: The Seven-Million-Year Story of How and Why We Survived”
When: 6 p.m. July 23
Admission: Free, but registration required
Where: Carnegie Library of Pittsburgh main branch, Oakland
Details: 412-622-8866 or www.pittsburghlectures.orgSubscribe today! Click here for our subscription offers.
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