Lead author here. It's true that longer sentences will have longer dependency length on average. That was one of the big methodological problems with previous p

Lead author here. It's true that longer sentences will have longer dependency length on average. That was one of the big methodological problems with previous papers that tried to show this. In the paper, we deal with this by doing stats on dependency length growth rate as sentences get longer, rather than averaging dependency lengths from sentences of different length. I'm sure that among the 7000 languages of the world there are some that don't minimize dependency length. But I'd be content showing it's an overwhelming tendency rather than a true "universal"!