Q:

Looking for the title of a sci fiction story about scientists studying evolution by sleeping for thousands of years

About 5 years ago someone emailed me a story in pdf form. I can’t find it or remember the title but would love to read it again. 
The story (what I remember!) humans were sent to a planet to observe/study the evolution of the planet and its creatures. The scientists were put to sleep for thousands of years, would wake up and document what they saw before going back to sleep. There were shifts of single scientists. One scientist realized the small creatures they encountered were intelligent and rather than watch them go extinct, chooses not to go to sleep but joins them to die. 
I’m sure I’m messing that up. Any help would be appreciated! 

A:

I think you are remembering Roger Zelazny's "The Keys to December", with some differences, but the kernel of the story matches.
A gene-altered group of humans obtains a planet that they plan to terraform to fit their new requirements.  The process takes tens of thousands of years, so they use cold-sleep to pass the time, waking up at intervals.  During the intervals, the protagonist discovers that the terraforming process is forcing some of the native creatures to evolve rapidly and they are becoming sentient. But if the process runs to completion, it will wipe them out...
He tries to get the group to stop the process, fails, and as you say, joins the creatures to die.

