A comparison of the two techniques used to estimate the timing of continental break-up has confirmed they give the same answers. Geologists and biologists are probably pleased to hear they're in agreement, but the reasons the study was done are more interesting to the rest of us, shedding light on the chances of finding ET.
The timing of the supercontinent Pangea break-up, and the subsequent dispersal of its main components, has been estimated using geomagnetic studies of rocks, and by measuring how long groups of animals and plants have been evolving independently. Huge discrepancies would probably have been noticed by now, but smaller differences might have slipped through. Surprisingly, until now, no one has done a comprehensive check.
Sarah McIntyre of the Australian National University needed to know the timing of continental isolations for her PhD thesis on the prospects of finding extraterrestrial life. Her supervisor, Dr Charles Lineweaver, was surprised to discover no one had really established them. “We had this conversation a number of times over the first few months,” McIntyre told IFLScience. “There had been a lot of previous research done on groups of animals like spiders or frogs, as well as on one continent, but no one had taken an overall global look.”
So McIntyre did it herself, carefully selecting vertebrates considered unlikely to cross oceans by flying, swimming or rafting. She used molecular clocks to determine when those on one continent or large island became cut off from those on another. Despite some complications, such as questions over whether a land bridge once joined Madagascar and Africa, McIntyre was able to show the biological data fits well with the geological estimates, bolstering our confidence in both. The work won her publication in the prestigious Proceedings of the Royal Society B.
But what, you are probably thinking, does this have to do with the search for extraterrestrial intelligence? The answer lies in Lineweaver's theory that life is probably common throughout the universe, but technological civilizations capable of communicating with us, let alone sending spaceships, are exceptionally rare.
Lineweaver has long disputed the “intelligence niche” theory, which holds that the benefits of tool use are so great that, given time, one species or another will eventually develop the brain power to harness fire, agriculture, and the wheel. If the intelligence niche was correct, Lineweaver says, isolated continents and large islands should have seen the growth of increasingly intelligent creatures from the time they became isolated until humans arrived from Africa to fill the niche.
McIntyre is investigating whether kangaroos, sloths, or lemurs were slowly increasing in brain size, relative to bodies, to see if the arrival of high intelligence is inevitable, or a rare fluke.
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