>>149458614
Long story short, the earliest hominids, given that they were still covered in fur, were probably light-skinned (like chimps are), but the situation was reversed once they went mostly hairless. Then, melanin replaced fur as a shield against UV radiation, so dark skin became the default. Things started to change once more after humans began to migrate and spread outside the tropics, although the diversification of skin tones was a gradual phenomenon, encompassing thousands of years.
Regarding Neanderthals specifically, while there's somewhat of a pop culture stereotype online that they were mostly light-skinned and giger-haired, it's unlikely that their complexions would have been all that different from those of their Homo sapiens neighbors.
To cut to the chase, light skin didn't start to become prevalent in Europe until 5,000 years ago, thanks to an influx of Near Eastern admixture. Less than 3,000 years earlier, it was pretty much endemic to the northern latitudes, with the populations of the central and southern regions being generally dark-skinned.
