Consider this: particle physics shows us that entangled observation (not to be confused with human or intelligent observation) ties past and future events together into a causative vector of influence.
Extrapolating from this using entangled observation similar to Einstein-Rosen bridges between quantum events suggests (mathematically) that there is a correlation between frames of references in real-space once a chain of events is initiated.
This would have the effect of linking independent causative frames such that the 'arrow of time' would diverge, probabilistically, between relative frames.
Or, attempting to explain this analogically:
The light from a distant star contains a tremendous amount of observable information about a star, and a limited amount of information about exoplanets (Doppler shift, chronographic direct imaging, etc...). As technology advances, however, it should be possible to tease out (observe) direct evidence of extrasolar life from this meager data due changes over time to how life changes a planetary atmosphere (specific to biome, but similar divergence vectors).
Depending on how one interprets causative entangled observation, this could actually have a strong anthropic effect on life. Evidence that alien life, intelligent or not, exists on an exoplanet would strongly influence the actions of any intelligent species towards visiting and exploring the planet. This would be very close to a strong motivational influence towards any intelligent social network, yielding a high probability outcome of events.
Depending on distance between planets and assuming that technological development is generally rapid, there becomes a high probability chance that any technological species would, inadvertently, directly affect the development (probably adversely) of all emergent evolutionary biomes within observational range.
As a species matures, they would probably realize this at some point, and take one of two divergent vectors: Some level of apathy (no empathy, just settle habitable planets or destroy competition) or avoidance (let them develop, don't interfere). Extrapolating those two motivational vectors, it's likely that there are those that would visit for nefarious reasons, and likely that there are those that would seek to prevent that type of interference due to social morays based on the above principles.