| ...after decades of focusing their attentions skyward, the Meinels – now in their 80s – are grappling with a question that seems, at first light, to be far, far away from astronomy. Namely: Why did modern humans and other species emerge some 40,000 years ago?
Their answer: Cosmic radiation, which the Meinels will elaborate on June 20 in a noon public lecture at the University of San Diego, part of the annual meeting of the Pacific Division of the American Association for the Advancement of Science.
Coming from almost anyone else, the suggestion that a burst of cosmic radiation profoundly mutated life on Earth and altered the course of human evolution would probably be dismissed as outrageous science fiction.
But Aden and Marjorie Meinel have been both serious and significant players in astronomy for a good chunk of the last century. ...Marjorie's interest was inherited: Her father, Edison Pettit, was one of the founding astronomers of the 102-year-old Mount Wilson Observatory, east of Los Angeles. Aden's interest evolved over time. It began as an apprentice in Mount Wilson's optics shop, through a stint in the Navy as a rocket engineer and at the California Institute of Technology, where his doctoral dissertation eventually resulted in the world's first solid Schmidt spectrograph – a device for measuring and charting wavelengths of light in space.
With Marjorie serving as adviser, editor and muse (and mother to their seven children), Aden launched a career designing, developing and directing observatories around the world. He helped establish the first national observatory at Kitt Peak, southwest of Tucson, Ariz., in the 1960s, then moved to Steward Observatory and taught at the University of Arizona. At various times, he helped build telescopes in India and China. In the 1980s, he and Marjorie moved to the Jet Propulsion Lab in Pasadena where they helped launch space-based telescopes like the Hubble. Aden retired in 1993, Marjorie in 2000.
While reading a story about ice-core research, Aden wondered whether the core samples also contained information about cosmic radiation levels over the Earth's history. To his and Marjorie's surprise, an examination of existing ice core data showed a significant surge in radiation roughly 40,000 years ago – about the same time, they noted, that modern humans emerged in Eurasia, and numerous other species in the northern hemisphere were either undergoing significant change or disappearing altogether.
“That's when we first became tempted to put two and two together,” said Aden. “If there was a large surge of cosmic rays, and there's good evidence that these rays can (cause mutations), the question becomes, did they help create new species of life?
“Our findings indicate that two very rare occurrences happened at roughly the same time, which suggests that how we've evolved might not be just slow, random mutation and natural selection. Maybe we are partly the product of cosmic radiation.”
The Meinels even have a likely source for the radiation: the gaseous remains of a dying star called the Cat's Eye nebula discovered by William Herschel in 1786.
According to their hypothesis, the nebula began emitting a burst of radiation roughly 200,000 years ago. “Around the time that Neanderthals began to appear,” said Aden.
Approximately 40,000 years ago, the frequency and intensity of the radiation surged, spawning in the Meinels' view, a host of evolutionary changes. “Then, about 10,000 years ago, the Earth passed out of the nebula's jet of cosmic rays, ending the accelerated mutations,” said Aden.
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