Charles Darwin took justifiable pride in his powers of observation. In his autobiography written towards the end of his life, he wrote:
On the favourable side of the balance, I think that I am superior to the common run of men in noticing things which easily escape attention, and in observing them carefully.
Yet even Darwin’s legendary attention to detail occasionally let him down. Such as on 15th September 1832, when he managed to travel an entire day with gauchos in Patagonia without realising the people wearing chaps weren’t all chaps:
The Spaniards, whom we some time since thought were Indians, have been employed hunting for us & have generally bivouacced near the coast. — They offered to lend me a horse to accompany them in one of their excursions; of this I gladly accepted. — The party consisted of 9 men & one woman; the greater number of the former were pure Indians, the others most ambiguous; but all alike were most wild in their appearance & attire. — As for the woman, she was a perfect non descript; she dressed & rode like a man, & till dinner I did not guess she was otherwise. —
Apparently, Charles Darwin didn’t have much of an eye for the ladies.