I've been wondering if the neanderthal may have had a much faster metabolism than we do. Evidently they had a much greater muscle mass. They might have had a metabolic advantage, as far as living in a very cold climate....? With adequate clothing tho, that is not an advantage, but a disadvantage, as it costs so much more in food. So now I am arguing against my own op.
I doubt it was any faster, metabolic rate is adaptive...the modern Inuit and Aleut peoples have a metabolic rate 13-33% higher than non arctic people, they have fewer sweat glands(sweating can be fatal in cold climates) and their blood vessels in their hands dilate quicker than non arctic people ...and it wouldn't require more food the food they eat is high in protein and fat...europeans living during the ice age would've developed the same or similar lifestyle and adaptations, as the climate changed their adaptations and lifestyle changed as well... whether that put neanderthals at a disadvantage is debatable they survived ice ages and periods between ice ages successfully so why would they suddenly be disadvantaged by what was previously a successful adaptation?...it's a good mystery...
it may be anthropologists have been placing far too much importance on physical appearance...modern man comes in a huge variety of shapes and sizes but DNA confirms we are still the same specie...IMO DNA (when it is available) has to be the first criteria for specie and sub-specie classification and not morphology...
