Similarity | Wallace | Darwin
natural history collecting in childhood | plants & beetles | beetles
different species separated by rivers | monkeys, insects & birds in Amazon (Rio Negro) | rheas in Patagonia (Rio Negro)
similar species across oceans | trogons (S. America & Malay) | mockingbirds, finches (American mainland & Galapagos)
species similarities & differences in archipelago | cockatoos, bird-wing butterflies & others (Malay) | tortoises, finches (Galapagos)
Malthus, On Population | 1846 reading | 1838 leisure reading