By Alan Boyle (not me)
Scientists are fond of running the evolutionary clock backward, using DNA analysis and the fossil record to figure out when our ancestors stood erect and split off from the rest of the primate evolutionary tree.
But the clock is running forward as well. So where are humans headed?
Evolutionary biologist Richard Dawkins says it's the question he's most often asked, and "a question that any prudent evolutionist will evade." But the question is being raised even more frequently as researchers study our past and contemplate our future.
Paleontologists say that anatomically modern humans may have at one time shared the Earth with as many as three other closely related types — Neanderthals, Homo erectus and the dwarf hominids whose remains were discovered last year in Indonesia.
Does evolutionary theory allow for circumstances in which "spin-off" human species could develop again?
Some think the rapid rise of genetic modification could be just such a circumstance. Others believe we could blend ourselves with machines in unprecedented ways — turning natural-born humans into an endangered species.
Present-day fact, not science fiction
Such ideas may sound like little more than science-fiction plot lines. But trend-watchers point out that we're already wrestling with real-world aspects of future human development, ranging from stem-cell research to the implantation of biocompatible computer chips. The debates are likely to become increasingly divisive once all the scientific implications sink in.
"These issues touch upon religion, upon politics, upon values," said Gregory Stock, director of the Program on Medicine, Technology and Society at the University of California at Los Angeles. "This is about our vision of the future, essentially, and we'll never completely agree about those things."
The problem is, scientists can't predict with precision how our species will adapt to changes over the next millennium, let alone the next million years. That's why Dawkins believes it's imprudent to make a prediction in the first place.
Others see it differently: In the book "Future Evolution," University of Washington paleontologist Peter Ward argues that we are making ourselves virtually extinction-proof by bending Earth's flora and fauna to our will. And assuming that the human species will be hanging around for at least another 500 million years, Ward and others believe there are a few most likely scenarios for the future, based on a reading of past evolutionary episodes and current trends.
Where are humans headed? Here's an imprudent assessment of five possible paths, ranging from homogenized humans to alien-looking hybrids bred for interstellar travel.