The Greek population doubled during the eighth century, resulting in more and larger settlements than previously. The largest settlements, such as Athens and Knossos, might have had populations of 1,500 in 1000 BC; by 700 they might have held as many as 5,000 people. This was part of a wider phenomenon of population growth across the Mediterranean region at this time, which may have been caused by a climatic shift that took place between 850 and 750, which made the region cooler and wetter. This led to the expansion of population into uncultivated areas of Greece and was probably also a driver for colonisation abroad.
Ancient sources give us little information on mortality rates in archaic Greece, but it is likely that not many more than half of the population survived to the age of 18: perinatal and infant mortality are likely to have been very high. The population of archaic Greece would have consequently been very young – somewhere between 40% and two-thirds of the population might have been under 18. By contrast, probably less than one in four people were over 40, and only one in 20 over the age of 60.
Evidence from human remains shows that the average age at death increased over the archaic period, but there is no clear trend for other measures of health. The size of houses gives some evidence for prosperity within society; in the eighth and seventh centuries, the average house size remained constant around 45–50 m2, but the number of very large and very small houses increased, indicating increasing economic inequality. From the end of the seventh century, this trend reversed, with houses clustering closely around a growing average, and by the end of the archaic period the average house size had risen to about 125 m2.