Posted by: Garfunkel
« on: October 26, 2012, 12:25:45 AM »It's a bug and will be fixed for next version. Steve addressed this in the Bugs 6.10 thread.
I'm still with 5.60, so I'm afraid I can't help you, sorry. Just can tell you that with 5.60 it's available as soon as you have genome sequence. Maybe Steve removed it in 6.X?
After researching genome sequence, I always found all the others unlocked, so I thought that is the only prerequisite.
By the way, you can have a look to the tech tree posted by Turmoil.
I don't believe you can change a races base gravity tolerance through research at all.