Bowser,

Much data is coming in from molecular & developmental biology as well as paleontology which indicates we are basically chimps. Bonobo's (formerly known as pigmy chimps), chimps, and us all have diverged about equally from a common ancestor with Gorillas branching off at most a few million years previously. Recent data even indicates that our brains are different primarily due to changes in development rather than basic genes. Kind of splitting hairs as development also is controlled by genes, but the differences are smaller than previously believed. Chimps were once far more widespread. The root cause in our divergence was shrinking forests which either left isolated island populations needing the ability to travel across treeless land or opened a niche for walking apes.

I think it can be reasonably postulated that on a planet with large forested continents where apelike creatures had evolved a climate change reducing forestation would have a fair chance of producing walking apes. Notice the large number of preconditions however. Evolving apelike form might be less likely than evolving bipedal locomotion from that form. I base that on the relatively few apelike creatures in the fossil record versus the number of bipedal organisms. No apes evolved from monkeys in the Americas and asian apes are descended from apes which originated in Africa. Dinosaurs never even evolved a monkey form. Birds are the closest thing although lovebirds sure remind me of monkeys in terms of their love of climbing and their gymnastics. Are apelike ancestors a necessary prerequisite for toolusing species? Maybe not, but many of our characteristics enabling tool use were based on apelike traits.

As far as DNA stability goes, it is generally speaking the same. DNA repair mechanisms are highly efficient and only rare errors cause mutation. The mechanism is the same across most knbown lifeforms. A few have additional mechanisms which come at a metabolic cost and possibly decreased adaptability. It is certainly unlikely that there would be much difference in stability between closely related species.

Hope that answers your ape questions. I wasn't sure how to answer somewhat rhetorical sounding questions.

In terms of the Drake equation it is often assumed that 400 billion stars in a galaxy and 400 billion galaxies means intelligence is not unique. Well all it takes is odds less than 1 in 400 billion to make the expected number of intelligent species < or + 1. While that may seem unlikely just assign a 1 % chance to each term of the Drake equation and see how low the odds go. Some factors are probably higher, but many may actually be much lower. My guess is the number of galaxies means we are not unique in the universe, but I think the odds per galaxy could be lower than 1.

My own view has been shaped by the belief that the time for any intelligent species as a technologically adept one is limited without developing access to space resources. Combine that with a belief that in turn will eventually lead to colonizing space and Fermi's paradox can no longer be hand waved away in my mind. I doubt we are the first to evolve, but I think we may be the only one left in our galaxy as others have succumbed to natural disasters or dangers raised by their own technology.

Regards,
Mark