Life before Earth

Biologists Alexei A. Sharov and Richard Gordon have written an interesting speculative paper about the origin of life on Earth and in the universe (see full 19-page paper here). The paper is at times tough going with molecular biology jargon. They used a computer simulation to get back to the simplest form of life.

They start: “An extrapolation of the genetic complexity of organisms to earlier times suggests that life began before the Earth was formed. Life may have started from systems with single heritable elements that are functionally equivalent to a nucleotide.”

Some of their speculations and conclusions:

“Linear regression of genetic complexity extrapolated back to just one base pair suggests the time of the origin of life = 9.7 ± 2.5 billion years ago.” That is older than Earth.

This cosmic time scale for the evolution of life has important consequences:

(1) life took a long time (ca. 5 billion years) to reach the complexity of bacteria;

(2) the environments in which life originated and evolved to the prokaryote stage may have been quite different from those envisaged on Earth;

(3) there was no intelligent life in our universe prior to the origin of Earth, thus Earth could not have been deliberately seeded with life by intelligent aliens;

(4) Earth was seeded by panspermia

(Panspermia: Theory that life on earth originated from organisms coming from outer space); I wonder if this begs the question. However did life originate elsewhere?

(5) experimental replication of the origin of life from scratch may have to emulate many cumulative rare events;

(6) the Drake equation for guesstimating the number of civilizations in the universe is likely wrong, as intelligent life has just begun appearing in our universe.

Physicist Luboš Motl, a fan pf panspermia, has some comments here.

Some of their other speculations:

“In summary, the functional complexity of human civilization grows exponentially with a doubling time ca. 20 years, but we do not see any signs of an approaching “technological singularity” when humans would be replaced by intelligent machines. Instead, we expect a stronger integration of human mind with technology that would result in augmented intelligence.”

 – Big Bang’s Sheldon Cooper can hardly wait.