Information Transmission via Molecular Communication in Astrobiological Environments.

The ubiquity of information transmission via molecular communication between cells is comprehensively documented on Earth; this phenomenon might even have played a vital role in the origin(s) and early evolution of life. Motivated by these considerations, a simple model for molecular communication entailing the diffusion of signaling molecules from transmitter to receiver is elucidated. The channel capacity C (maximal rate of information transmission) and an optimistic heuristic estimate of the actual information transmission rate $ℐ$ are derived for this communication system; the two quantities, especially the latter, are demonstrated to be broadly consistent with laboratory experiments and more sophisticated theoretical models. The channel capacity exhibits a potentially weak dependence on environmental parameters, whereas the actual information transmission rate may scale with the intercellular distance d as $ℐ$ ∝ d^-4 and could vary substantially across settings. These two variables are roughly calculated for diverse astrobiological environments, ranging from Earth's upper oceans (C ∼ 3.1 × 10³ bits/s; $ℐ$ ∼ 4.7 × 10^-2 bits/s) and deep sea hydrothermal vents (C ∼ 4.2 × 10³ bits/s; $ℐ$ ∼ 1.2 × 10^-1 bits/s) to the hydrocarbon lakes and seas of Titan (C ∼ 3.8 × 10³ bits/s; $ℐ$ ∼ 2.6 × 10^-1 bits/s).