Humanity’s Beta Versions

Photo by Fred Spoor

People who aren’t scientists tend to view evolution as a linear series of incremental improvements, like one of those illustrations of a fish climbing out of the water and growing legs, then walking upright, then holding a briefcase. The truth, however, is much messier.

We are the way we are today as a result of millions of years of random (and sometimes unhelpful) mutations. Humanity’s rambling developmental path was reaffirmed last month when research published in Nature confirmed that around 2 million years ago there were multiple species of Homo existing in the same region of Africa simultaneously, and not just our direct ancestor Homo erectus. It was one giant Homo party, if you will.

The article provides an overview of several fossil fragments, including an important portion of a jawbone that provides proof, the authors say, that an upright monkey scientists had named Homo rudolfensis was definitely a separate species (one with a distinctly flat face) from our erectus forebears. These two species lived alongside a third would-be human ancestor known as Homo habilis during a period of our evolution that we still don’t adequately understand.

“The real gap is the period between 2 and 3 million years ago,” said Fred Spoor, one of the paper’s authors. “The areas where these ancestors of ours lived didn’t have the right conditions to produce the fossils we’re after.”

This period of evolution is especially important—it’s during this time that we transitioned from upright-walking chimps to the tool-using world-conquerors we are today.

Chances are we’ll continue to discover new varieties of almost-humans for some time to come, as we did in 2003, when the remains of four-foot-tall humans called Homo floresiensis were found in Indonesia. The “Hobbits,” as they’re known, used tools flourished at some point in the past 100,000 years—a blink of the eye, archaeologically speaking. Spoor said they were another example of the unexpected turns evolution can take.

“Animals isolated on their own islands can have their own crazy development,” Spoor said. “We say, ‘Oh well, this isn’t going to happen to human ancestors,’ but it just shows that even relatively late, this [diversity] still happened in human evolution, too. We’re increasingly finding out how this happens. It’s just a matter of finding the fossils.”

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