As population grew, so did its environmental imprint, including forest clearing by burning, building of "heiau" at agricultural sites, and the decline of indigenous plants. The paleo-environmental data show that during 1450-1778 the construction of "heiau" slowed dramatically, as did the clearing of land for agriculture. Accordingly, the estimated population in 1778 was 110,000-150,000. It is believed relying on the archaeological data and oral traditions, that the social organizations evolved after the initial settlement as the population increased. During the initial settlement and growth phase on the island the social organizations were characterized by semi-independent chiefdoms organized as single nonegalitarian corporate units on each island, which is essentially the same as ancestral Polynesian society. During the expansion inland and growth phase which lasted until about 1500–1550, the formation of basic ahupua'a land units which saw the widening of the gap between chief and commoner as the concept of kinship increased within the local community with the formation of ali'i and maka'ainana classes. The significant reduction of population in the 16-17th century was a result of warfare and conquest among competing chiefs as well as the rise of Aikāne (homosexual) relations. Liloa originated the practice of "moe āikane", the sexual relationship between males in the late 15th century.