I already pointed out in the past that Neanderthals had larger brains than Early Modern Humans(Cro-Magnonish Upper Palaeolithic types), that they likely had larger encephalisation quotients(ie brain-size-to-body-mass ratio) due to being much shorter, albeit also stockier than Early Modern Humans. I also pointed out that the Neanderthals appear to have discovered all sorts of practices, such as tool-use/fire etc. long before Early Modern Humans came on the scene, 100s of thousands of years before even.Now, according to the above article, Neanderthal brains took longer to mature than those of humans. Now, scientists have in the past pointed out that one of the key differences between chimpanzees and modern humans was that humans took longer to reach maturity, and this was cited as a key trait leading to the higher intelligence in humans(as a longer time to reach maturity means a longer time for learning and developing the brain). So, if the Neanderthals had a longer time to mature, then they were presumably more intelligent. Nothing conclusive, of course, it's just that I was always suspicious of the biased, humanocentric claims in the 70s/80s onwards by Out-of-Africa theorists that Neanderthals were just dumb brutes unable to speak etc.