Experts who tweaked the Drake equation have found that the Earth may not be the first planet to hold an intelligent civilization in the universe. The results of the investigation imply that the evolution of advanced life may not be confined simply to present-day humanity.

The investigators played with the long-existing equation and as a result, the scientific community shifted focus once more on the possible existence of advanced alien civilizations — regardless of when such life existed throughout the history of the universe.

Analysis showed that there exist less than one in 10 billion trillion chance that human civilization evolved on Earth and nowhere else in the universe.

Drake Equation Then And Now

Drake equation was formulated by astrophysicist Frank Drake in 1961 with a goal to identify how many advanced civilizations possibly exist in the Milky Way.

The original Drake Equation is N = R* x f_p x n_e x f_e x f_i x f_c x L.

N is the total number civilizations in the Milky Way; f_p is the fraction of the R* that has planetary systems; R* is the rate of star formation.

Next, n_e is the number of planets in each solar system that has a life-suitable environment; f_e is the fraction of planets where life is present; f_i is the fraction of life-containing planets where intelligent life emerges; f_c is the fraction of civilizations that create technology that emits apparent signs of existence into space. Lastly, L is the time such civilizations emit detectable signals into space.

Even though the Drake equation is recognized to provide a firm foundation for research and space technology, the farthest that experts can go is to guess.

Now, a new study tweaked the classic equation to address a slightly varied inquiry: How many advanced civilizations more or less have developed in the span of the observable universe's existence?

To answer this, the team of Adam Frank and Woodruff Sullivan drew back to the Drake equation, but this time, they removed the variable L.

They developed a new formula consisting of R*, f_p and n_e, which is the average number of planets in the habitable zones or those that contain water and, therefore, life. The product of the said variables is termed by the scientists as N_ast. While f_bt is from the product of f_e, f_i and f_c.

The team then came up with an Archaeological form of the Drake equation: A = N_ast * f_bt.

A is the number of technological elements that have ever developed over the lifespan of the observable universe. This could be obtained by multiplying N_ast with f_bt, which is the chance that a technological species may develop on the planets.

Real Question: Frequency Of Evolution

For a long time, the focus has been on the number of civilizations that may exist at the present moment. Shifting the question to asking if the civilization on Earth is the only one ever existed enables experts to eradicate the vagueness of the long-existing query.

Through their work, they can now give the limelight to what they call as the "cosmic archaeological question," which is the frequency of life turning into an advanced state all throughout the history of the universe.

The question has been tweaked to become less complicated; still it is very difficult to measure the odds of advanced life evolution. So, the team shook up the question once again.

Instead of predicting the probability of advanced life developing, they looked into against the chances of humanity in being the sole advanced civilization in history.

The duo then measured the line between a dimension where humans have been the only subject of civilization experiments and a dimension where other species have existed before humans.

"Of course, we have no idea how likely it is that an intelligent technological species will evolve on a given habitable planet," says Frank. He adds, however, that using their technique can determine exactly how low such odds would have to be for humans to be the sole civilization that ever existed in the universe - a thing they call pessimism line.

If the real probability exceeds the pessimism line, then the technological elements and civilization have more or less existed in the past.

The researchers calculated the unlikeliness of advanced life if there have been no other samples in trillion of stars in the universe or even in the hundred billions that exist in the Milky Way.

They found that human civilization is most probably unique in the universe only if the odds of civilization occurring on a habitable planet are less than 1 billion trillion.

Frank says that figure is significantly small, but still the results imply that there exists a possibility that intelligent technological species have evolved before the present-day humanity.