- The Cygnus Mystery -
Have Cosmic Rays Affected Human Evolution?
by Andrew Collins
Cygnus X-3 taken by the Chandra X-ray Observatory.
Did cosmic rays have a hand in effecting shifts in
human evolution, from Palaeolithic times through to the modern day? Has this
helped determine not only our physique and behaviour, but also our creativity
and consciousness? These are wild notions, yet suddenly they are beginning to
appeal to main-stream scientists and astronomers. Indeed, as long ago as 1973
American astronomer and science writer Carl Sagan wrote in his book The Cosmic
Connection that human evolution was the result of incoming cosmic rays from
some distant neutron star, demonstrating how we are right to think of ourselves
as part of a greater whole at one with the cosmos.
Yet is this correct? Is Charles Darwin's theory that
evolution is caused merely through survival of the fittest, and the process of
natural selection, somehow flawed? The idea of cosmic radiation reaching Earth
from deep space has fascinated the scientific world since its discovery
following a series of balloon ascents by Austrian physicist Victor F Hess
(1883-1964) in 1912. Then when in the late 1920s American geneticist H J Muller
(1890-1967) discovered that radiation (he used X-rays and later radium) was a
mutagen through his work with Drosophila fruit flies, the subject of whether or
not high energy cosmic rays might cause changes in human DNA was voiced for the
first time. Muller himself twice wrote about the subject, concluding on each
occasion that the normal background fluctuation in cosmic rays reaching Earth
was inadequate to explain spontaneous mutations in life forms, whatever their
type. Muller was not wrong. Yet had he been privy to modern scientific data
which now confirms that at certain times in the Earth's history the solar
system has been bombarded with high levels of cosmic rays then he might have
thought again.
When so-called "primary" cosmic rays hit the
upper atmosphere almost all of them break up when they collide with nuclei of
oxygen and nitrogen, the process producing a plethora of charged secondary
particles. Many disintegrate in milliseconds, but others form isotopes that are
preserved in everything from lake sediments to stalagmites and, more crucially,
the layers of ice that accumulate each year to great depth in the Arctic and
Antarctic regions.
One such isotope is Beryllium-10 (10Be), which can be
extracted from ice cores and measured to provide an accurate indication of
cosmic ray activity in the upper atmosphere. It shows that over the past
100,000 years, there have been three periods when the cosmic ray flux has
increased dramatically. The first was around c. 60,000-70,000 years ago, the
second occurred approximately c. 35,000-40,000 years ago, and the third and
last peak began around c. 16,000-17,000 years ago, and continued until around
14,000 years ago. Each spike lasted for a period of approximately 2,000 years.
Similar results have been determined from a stalagmite removed from a submerged
blue hole in the Bahamas. An examination of its Beryllium-10 content indicates
that at various points between 45,000 and 11,000 years ago the Earth was
bombarded by twice the amount of cosmic radiation than we get today.
Where's the Cosmic Source?
The first question we must ask is where this influx of
cosmic radiation might have come from. Was it really a neutron star, as Carl
Sagan suggested, or could it have been another astronomical source out there in
deep space? Alternatively, was there some other, more prosaic solution to this
enigma? The more or less regular gaps between the spikes of Beryllium-10
activity noted in the ice cores might well indicate some kind of cyclic force
in action, most obviously that of the sun. Cosmic rays are known to be
partially deflected by the solar magnetic field that stretches far out into the
heart of the solar system, making the rate of Beryllium-10 production in the
upper atmosphere dependent on the strength of the solar field, which is itself
connected with sunspot activity.
In addition to this, the sun's long term climate
cycles of 100,000, 41,000 and 23,000 years, first noted by Serbian geophysicist
Milutin Milankovic (1879-1958), must also affect the production of Beryllium-10
for similar reasons, i.e. the influence of the solar field upon the Earth's
upper atmosphere. This said, there might easily have been other factors behind
the sudden increase in cosmic rays hitting the earth, the most catastrophic
being a supernova, the death of a star as it expels the last of its nuclear
fuel and collapses to form a high-mass compact object, most usually a white
dwarf, black hole or neutron star.
Supernovas are thought to produce enormous bursts of
cosmic rays and gamma rays, which are sent careering across space at virtually
the speed of light. If such an event occurred close enough to our own solar
system then the Earth would be showered by deadly radiation. This would damage
the ozone layer, causing not only many more rays to reach the surface of the
planet, but also the onset of high levels of UV radiation from the sun. More
conservatively, catastrophists suggest that cosmic rays from a close supernova
would dramatically increase cloud formation, preventing the sun from
penetrating through the atmosphere, thus bringing about a sudden ice age.
Whatever the consequences of a close supernova, life
on Earth would suffer mass extinctions. As terrifying a scenario as this might
seem, it was the favoured theory for the sudden disappearance of the dinosaurs
some 65 million years ago until the discovery in 1980 of the Chicxulub impact
crater in Mexico's Yucatan peninsular. This helped confirm the alternative
theory that a super-sized asteroid or comet had been responsible for their
extinction. Indeed, the supernova solution had been the choice of Carl Sagan
and his co-author Dr I S Shklovskii, the famous Soviet astrophysicist and radio
astronomer, in a book entitled Intelligence in the Universe, published in 1966.
In fact, one wonders whether Sagan's unique view that cosmic rays have
accelerated human evolution actually stemmed from his obvious fascination with
the extinction of the dinosaurs.
Yet the powerful idea of a close supernova wreaking
devastation on earth during some past geological age lingers, with some
catastrophists believing that it could have brought about mass extinctions
during other geological epochs, for instance at the close of the Jurassic age
some 145 million years ago, as well as at the culmination of the Pleistocene
age, which coincided with the end of the last Ice Age, some 12,000 years ago.
And such scientific speculation is where it starts getting interesting, for
when the high levels of Beryllium-10 were first noted in the ice cores at the
beginning of the 1990s, scientists from the Cosmic Ray Council of the Soviet
Academy of Sciences, working alongside a team from the University of Arizona,
speculated that those around 35,000-40,000 years ago probably resulted from a
supernova explosion.
To back up their dramatic claims the joint
Soviet-American team cited the presence of an immense formation of glowing
clouds of gaseous debris - the remnants of an unimaginable supernova explosion
at around 150 light years away (that's just 900 million, million miles from
here) in the northern constellation of Cygnus. Had this remnant of a supernova
explosion - known to astronomers as the Cygnus Veil, or Veil nebula - been
responsible for showering the Earth with cosmic rays for anything up to 2,000
years some 40,000-35,000 years ago? Did it bring about dramatic climatic
changes and bursts of radiation that evolved humanity into what we are today?
The Emergence of Man
For whatever reason, the worldwide press coverage that
resulted from this dramatic announcement of a close supernova decimating the
Earth some 35,000 years ago came to nothing. Yet, thankfully, there was one
person who did take notice, and this was British anthropological writer Denis
Montgomery. Having lived in Africa for many years, where anatomically modern
humans emerged for the first time around 200,000 years ago, he became intrigued
as to why sudden jumps in evolution occur. Was it purely spontaneous, through
chemical changes in the body, or were there other exterior factors at play,
such as environmental and climatic changes, nutritional variety, interbreeding
or even simple competitiveness?
