“They found that muscle activity was significantly higher on the left side of the body for spear thrusting tasks relative to the right side of the body. This does not explain the observed Neandertal morphology, though, which shows dominant strength on the right side, casting doubt on the hypothesis that spear thrusting was responsible for the observed asymmetry.”
The assumption is that Neandertals were right handed in the majority instead of left handed, like modern man. Maybe Neandertals were left handed in the majority. Do they know, or did they make an unwarranted assumption?
If they’d found that Neandertal were primarily left-handed, it wouldn’t help the “we aren’t related to them” crowd — lefthandedness would then be seen as more evidence that we are. :’)
It’s a safe assumption that N was mostly right-handed because of these characteristics (the more heavily developed right) in surviving remains. Other than modern, recently-deceased humans, Neandertal remains are the most numerous in the fossil record. IOW, there *may* have been more left-handed Neandertals, but the right-handed ones made all the weapons and left all the remains — not likely.