Astronomers now think that life spread throughout the Milky Way via microbes hitching a ride on asteroids and comets, and that it didn't originate on Earth. It will eventually leak out into other galaxies?if it hasn't already. This means that life is probably widespread, although the planet(s) where life originated may now be barren or may never be identified. However, this doesn't mean ET will look familiar, because evolution can take many twists and turns.
David Whitehouse writes in bbcnews.com that astronomers Max Wallis and Chandra Wickramasinghe believe microbes can survive a journey of hundreds of millions, maybe even billions, of years, because they've discovered microbes that have survived for similar periods inside rocks on Earth. They say that only a tiny amount of "spore-bearing material is plenty for seeding a new planetary system with life." People who deny the reality of evolution point to gaps in the fossil record. But recent studies show it's possible to watch evolution in action.
Biologists at the University of Chicago replaced a single gene in fruit flies and created two different "races." Since these different types of flies only liked to mate with their own kind, they quickly turned into two different species of fruit fly. One group was adapted to life in the tropics, while the other liked cooler climates. The tropical flies were more tolerant of starvation but less tolerant of cold. The temperate group was less tolerant of starvation but better adapted to cool weather.
The altered gene also changed the flies' pheromones, which are the chemical signals that influence mating behavior. This meant there was no cross-mating, since tropical flies were only attracted to other tropicals, and vice-versa. Researcher Tony Greenberg says, "We had the luxury of watching the essential event in Darwinian evolution, the first step in the origin of a new species. We were quite impressed, that this simple alteration played such a dramatic role, both adapting flies to a new environment and changing their sex appeal. Once two groups become sexually isolated, there's no turning back."
Fruit flies are a lot like humans in that they originated in Africa, spread to Europe and Asia and then went on to populate the world. As with humans, there is greater diversity within African flies than between flies from Africa and other continents.
Did you know that UFOs are common in human history, all the way back to prehistoric times? You can see this by looking at how they're depicted in art. Don't miss Whitley's interview with Matthew Hurley about this fascinating subject on this week's Dreamland. To learn more, click here and here.
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