Not of this Earth

Since the beginning of human history, there have been many theories on the origin of life. Some theories include a creator or designer and some include life materializing spontaneously through chemical reactions. Regardless of what set it in motion, there are theories of where it actually began, ranging from the deep depths of the ocean to frozen ice caps to clay and to, most interestingly, the far reaches of outer space.

The concept that the origin of life came from space sounds like something from a science fiction movie. I’m looking at you, “Prometheus.” However, the idea has been around for a long time (over 2000 years in fact). A Greek Philosopher named Anaxagoras was the first to propose that life began in space. He believed that the universe was made up of an infinite amount of seeds which took root when landing on Earth and created life forms. He called this panspermia, which translates to “seeds everywhere.”

Two thousand years later in 1908, Svante Arrhenius, a physical chemist stole this term, “panspermia” for his own origin of life theory. Well, it wasn’t much of a origin of life theory since he expressed that life had always existed in the universe and therefore didn’t need an explanation for its origin. However, he did believe that life forms could be transported from planet to planet.

An image from the cover of Arrhenius' book "The Biological Big Bang". Image from Amazon.
An image from the cover of Arrhenius’ book “The Biological Big Bang”. Image from Amazon.

He proposed that bacterial spores could travel through space by radiation pressure. This was to combat the previous theories of bacteria arriving to earth on meteorites. The problem with such meteorite-based theories is that the high temperatures the meteorites experienced coming through Earth’s atmosphere. Arrhenius attempted to find a way around that by saying that bacterial spores arriving by radiation pressure and attached to interstellar dust could fall slowly to the ground without reaching high temperatures.

However, this theory bit the interstellar dust when scientists found that bacterial spores wouldn’t be able to survive the exposure to ultra-violet radiation while traveling through space. After that, theories on the origin of life tended to center around the prebiotic soup theory.

Recently, theories about life with extraterrestrial origins have emerged again. Maybe it’s not as exciting as finding bacterial spores from outer space, but scientists have discovered organic molecules, such as amino acids, on numerous meteorites that have landed on Earth. These are basic building blocks of life, so scientists assumed that complex molecules still originated on Earth.

Chemists from the University of California and the University of Hawaii have created an experiment that suggests otherwise. It is possible for the conditions of space to produce dipeptides, which are more complex molecules necessary for the building blocks of life. Recreating the conditions of space, they were able to create a chemical reaction that produced nine different amino acids and at least two dipeptides.

It’s possible these complex organic molecules could have hitched a ride to Earth via comets or meteorites. That could have then created a catalyst that jump-started the creation of more complex proteins and sugars necessary for life.