It’s very hard to predict where evolution is going to go. If you wound back the evolutionary clock to the start of life and let it run again, it’s very unlikely that you’d end up with anything resembling humans – or any of the species we’re familiar with today. Natural selection builds-up chance events – mutations happen at random, some of which increase the chance of the animals carrying them passing on those mutations to their offspring. If life only started once, every creature on earth has had the same amount of evolutionary time to develop, and you can see just by looking around that they’ve all taken different routes.
Monkeys are some of the animals that have taken a similar route to humans. They’re not our closest class of living relatives – the great apes, like gorillas, organ-utans and chimpanzees are closer to humans than monkeys, but they’re pretty close. Biologists think we split off from monkeys about six and a half millions years ago, which isn’t that long in evolutionary time. Apes and monkeys have shown basic human-like intelligence in some circumstances, and they are mostly very social animals (much like us). Some biologists argue that one of the factors that contributed to human intelligence was the need to keep track of all the different social relationships within the group. Basic versions of this have been seen in chimpanzees, so it’s entirely possible that over time, such behaviour could evolve into something that we might recognise as “human-like” intelligence. Whether humans would still be around to see it is another matter. If such a thing happens, it will be over the course of thousands, perhaps millions of years. There may not be anything left we would recognise as “human” by then