My point exactly. If we evolved from fish-laying eggs, to egg-laying mammals, why couldn't we be mammals that laid eggs while swinging from trees. Birds lay eggs in trees. Seems a natural progression that primates, along their evolutionary path, would lay eggs in trees, unless they'd already learned about the live-birth thing. Eggs are much less fussy (unless you're a penguin) requiring more attendance after hatching. On the other hand, live births incapacitate the female to a certain extent due to carrying and nursing her young. Not to mention the immediate demands of the newborn, whether hatched or birthed. Laying eggs and letting the young develop outside the mother is much less demanding than the newborn developing inside the mother. Nobody has explained how we went from one to the other. If so, and we are so smart, why did we adapt to the more cumbersome and demanding live birth instead of egg laying. Because we were too busy swinging from trees and that whole egg-sitting thing was just a bother in ADHD primates? We were too busy eating parasites off our neighbor to sit on our own eggs, so lets just evolve to pop out our young. We'll carry them on our back today, and as soon as the first Walmart opens in a few cajillion years we'll get one of those sling thingys to carry them. Evolution at its finest.