Avian clutch size of increasing clutch size with increasing latitude. The proximate and ultimate causes for this pattern have been a subject of intense debate involving the ideas of group and individual selection. David Lack observed a direct relationship between latitude and avian clutch size. Birds near the equator laid approximately half as many eggs as those that resided in northern temperate habitats. He observed an increasing clutch-size from the equator towards the poles (something he referred to as the “latitude trend”) for many passerine (perching) birds, near-passerine (tree-dwelling) birds and in various other groups: Strigiformes, Falconiformes, Ciconiiformes, Laridae, Ralliformes, Galliformes, Podicipedifomes, and
Birds' Head Haggadah illuminated manuscripts from the 13th and 14th centuries depict humans with animal heads in keeping with this prohibition. Notably, the Leipzig Machzor, copied by the same scribe who copied the Birds' Head Haggadah, features human-looking faces with noses resembling curved beaks. Epstein theorizes that the choice of birds' heads for the Jewish figures in the Birds' Head Haggadah hints at the spiritual and national characteristics of the Jewish people. He argues that the beaked visages in the manuscript are not birds' heads at all, but the heads of griffins. The legendary griffin – the body of which resembles both a