Supernovae that bombarded Earth with energy millions of years ago may have resulted in our ancient ancestors learning to walk upright.
Electrons from the energy released from the exploding stars triggered by surge in lightning strikes, a new study suggests. 19659003] These strikes sparked forest fires around the globe, with savannas arising to replace the scorched woodlands.
Prehistoric humans – or proto-humans – lived their lives on all fours in these forests before shifting to two to adapt to the new plains as far back as eight million years ago, experts say,
Exactly why and when our distant ancestors stood upright and started moving around on two feet is widely debated by scientists.
This study, from the University of Kansas, claims that this was a knock-on effect from the supernovae
These stars reached the end of their life and their energy reached Earth during the transition from the Pliocene Epoch to the Ice Age. 04] Scroll down for video
This initiated an avalanche of electrons in the lower atmosphere. Atmospheric ionization caused by waves of energy started lightning strikes that resulted in forest fires in northeast Africa.
The destroyed forests were then replaced by wide expanses of mixed woodland and open grassy plains.
The need to climb trees, because of this expert say human evolution took place on two legs.
Lead author Adrian Melott, a professor emeritus of physics & astronomy at the University of Kansas, even before this event, was already a tendency for hominins to walk on two legs.
'But they were mainly adapted for climbing around in trees. After this conversion to savanna, they would much more often have to walk from one tree to another across the grassland, and so they become better at walking upright.
'They could see over the tops of grass and watch for predators. It's thought this conversion to savanna contributed to bipedalism as it became more and more dominant in human ancestors. '
Based on a numerical layer of iron-60 deposits lining the world's sea beds, astronomers have high confidence supernovae exploded near Earth during the transition from the Pliocene Epoch to the Ice Age.
Iron-60 is extremely rare on this planet with no known natural means to produce it, which leaves from space as the logical origin.
The team calculated the ionization of the atmosphere from cosmic rays which would come from In supernova about as far as the iron-60 deposits indicate, "Professor Melott said.
Ionisation is the process at which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons.
'Usually, you don't get lower-atmosphere ionization because cosmic rays don't penetrate that far But the more energetic ones from supernovae come right down to the surface – so there would be a lot of electrons being knocked out of the atmosphere, "he added.
As far back as eight million years ago, prehistoric humans, or proto humans, lived their lives on all fours before shifting to two. Exactly why and when our distant ancestors stood upright and started moving around on two feet is still widely debated. Here, artist's impression
Ionisation in the lower atmosphere meant an abundance of electrons would form more pathways for lightning strikes, according to Professor Melott.
'When high-energy cosmics hit atoms and molecules in the atmosphere, they knock electrons out of them – so these electrons are running around loose instead of bound to atoms, he added.
Lightning occurs when there's a buildup of voltage between clouds and the clouds and the ground. flow because not enough electrons are around to carry it so it has to build up high voltage before electrons start moving.
These knock more electrons out of more atoms and the builds to a lightning bolt.
But with ionization that can be started much more easily, resulting in more lightning bolts.
WHAT IS A SUPERNOVA AND HOW DOES IT FORM?
A supernova occurs when a star explodes, shooting debris and particles into space
A supernova burns for only a short period of time, but it can tell scientists a lot about how the universe started.
One kind of supernova has shown scientists that we live in an expanding universe, one
In 1987, astronomers spotted a titanic supernova in a nearby galaxy blazing with the power.
In 1987, astronomers spotted a "titanic supernova" in a ne arby galaxy blazing with the power or over 100 million suns (pictured)
There are two known types of supernova.
The first type occurs in binary star systems when one of the two stars, a carbon-oxygen white dwarf, The white dwarf accumulates too much matter, causing the star to explode, resulting in a supernova.
The second type of supernova occurs at the end of a single star's lifetime. 19659004] As the star runs out of nuclear fuel, some of its mass flows into its core.
Eventually, the core is so heavy it can't stand its own gravitational force and the core collapses, resulting in another giant explosion.
Many elements found on Earth are in the core of stars and these elements travel on new stars, planets and everything else in the universe
The probability of a lightning spike kicking off and upsurge in wildfires is supported found in soils by the discovery of carbon deposits.
Researchers found that these soils correspond with the timing of the cosmic-ray bombardment, landing more credence to their theory.
The observation is that there is a lot more charcoal and soot in the world starting a few million years ago, 'Professor Melott said.
'It's all over the place, and nobody has any explanation for why it would have happened all over the world in different climate zones.
No such event is likely to occur again anytime soon.
Betelgeuse, some 652 light years from Earth.