Mesopotamia

Climate.

The climate of Mesopotamia is continental in type with great extremes, and Mesopotamia and the Persian gulf are among the hottest places on the face of the globe. The mean annual range is nearly F in Baghdad, where the hottest month August has a mean temperature of 92.5°, a temperature as high as 123° having been recorded. The coldest month is January with a mean temperature of 48.8, the lowest recorded temperature being 19°. Except near the Persian gulf the humidity is low, making the extreme heat of summer less oppressive. The rainfall is usually under ten inches, falling mostly during the winter months, June to October inclusive being practically rainless, al though on the hills there is a larger precipitation. On the plain irrigation is absolutely necessary for the crops, rain only falling on an average of 26 days in the year.

In this hot dry land the winds are of importance, both for the relief they bring to the intense heat and for the dust storms they cause. The prevailing north-west wind, the Shamal, blows both summer and winter, sometimes blowing with great strength dur ing the heat of the day.

There is no exact information at present about the climate of Mesopotamia in ancient times.

Such evidence as there is suggests that, within historic times at least, there has been no great change, such variations in the siting of cities and so on being rather due to an alteration in the direction of the rivers than to an actual change in climate. It is certain that in palaeolithic times the region was much wetter and no doubt at this time the dry wadis which lead down from the Arabian plateau carried water. The tributaries of the Tigris may have changed slightly (see TIGRis) but insufficiently to warrant the suggestion that the desiccation is not of great antiquity, at least as far back as the Neolithic age.

Flora and Fauna.

While it may be said that Mesopotamia forms part of the region called by P. A. Buxton the "Palaearctic Desert" there are considerable differences in the flora and fauna of the different parts. Northern Mesopotamia, the region through which the rivers flowed previous to the accumulation of the deltaic region, has a Mediterranean flora and fauna. It seems probable that wheat and barley are here close to their original wild home. On the whole the region is treeless, although there are trees on some of the hills. In southern Mesopotamia other conditions prevail. The rainfall is not really insufficient to support a consider able amount of vegetation but owing to the physical qualities of the soil, a very fine silt, combined with a high temperature and strong winds the evaporation is excessive. Under these circum stances the regions between the rivers often approach to more truly desert conditions than the north Syrian desert. As an example the unirrigated regions near Kish are in places absolutely devoid of vegetation and at one point in an area of about a square mile the only living plant found was a bush of Christ's thorn.

Where however irrigation is practised and the water is allowed to drain off so that an excess of salts is not accumulated the soil produces good crops and after the crops abundant weeds of culti vation and a thorny flora of various species of a wide distribution in the palaearctic desert region. These weeds are extensively used for fire wood, a clear indication of the meagre floral resources of the country. The country is practically treeless, the only timber being supplied by the stems of the date palm, which grows along the rivers. There are also low beds of poplar. The vegetation along the rivers amounts to an extended oasis, although in places even the river banks are extraordinarily desolate. One of the characteristics of Mesopotamian vegetation as a whole is the com paratively few number of species which occur, a great contrast to the flora of the American desert. Secondly in common with all deserts the Mesopotamian vegetation shows a convergence of form between different species so that plants only distantly related are superficially similar. Thirdly, and this feature is also common to most deserts, the line which divides the green fertile land and the desert is very sharply marked, and the introduction of water by irrigation rapidly produces a marked change in the vegetation.

The fauna has as yet been imperfectly studied. Among large mammals the cheetah is not uncommon on the desert, the only other mammals of any size being various species of gazelles and antelopes. The lion so prominently figured on Assyrian bas-reliefs is said to exist, but recent records are uncertain. The wild ass is rare. Among the carnivora other than those mentioned the hyaena and species of wolves have been reported. The jackal is not un common and in certain regions wild pig abound. The desert hare is very common and where caves exist there are bats. Small mam mals are extremely common, especially jerboas and their allies. Among the birds the ostrich reported as quite common by Xenophon is practically if not entirely extinct. The birds of prey are well represented, including the vulture, raven, owl and various species of hawks. In the steppe region the buzzard is very com mon, there are various species of sandgrouse and, where there is open water, ducks and geese ; the black partridge is abundant near water. Among the reptiles one of the commonest and most inter esting is the little lizard Agama. The details of the smaller animals are not yet worked out. P. A. Buxton has noted the fact that whereas in the stony desert the pebbles shelter a host of woodlice, millipedes, centipedes, spiders, scorpions, earwigs, cockroaches, crickets, beetles, bugs and ants and lice in southern Mesopotamia a similar fauna is found in the leaf-bases of the palm trees. Apart from technical lists the most interesting account of plant and animal life in Mesopotamia is found in P. A. Buxton, Animal Life in Deserts, London 1923.