Glory be to god, today I have seen with these my own eyes, in vivo evidence of the wonderful molecular theory of de Selby, reported in the Dalkey Archive by the learned Father Flan O'Brien.
I was waling by the river in Cambridge when a bicycle went past with an adult home sapiens on it, unsurprisingly, you might observe, but then, right behind, was a much smaller bicycle with a much smaller human, who I can only surmise was a child of the larger human.
One must assume that when the child climbed on the bike, the admixture of molecules casued it to become more childlike, and, further, because of the familial relationship between the human in front, and the child behind, the foremost bike evolved a hand to reach out and hold the rearmost bicycle, just as its rider might do on foot.
Mirabile dictu, the first evidence. An interesting experiment suggests itself, which would be to see if placing the child on a bike in front of its riding parent would systematically work in the same way, or would the riders and bikes turn around to go the other way.
of course, were the council to improve the road surface, as de Selby reports, the problem might go away.