Selon la théorie essentiellement typologique de S. Trimingham concernant l'islamisation en Afrique occidentale, trois types d'islamisation ont eu cours, d'ordre commercial, clerical et militaire, mais les deux premiers restent les plus fondamentaux. Ce sont pourtant surtout les activités commerciales plus ou moins liées au commerce à longue distance qui ont constitué la base de l'islamisation jusqu'à la formation d'Etats islamiques au Moyen âge comme les Empires du Ghana, du Mali, du Songhay et du Kanemou-Bornou. Mais l'islam y resta marginal et, selon la terminologie de Trimingham, au niveau de “class religion”, sa sphère se limitant à certains groupes commerciaux plus ou moins étrangers aussi bien qu' à une partie de la population appartenant à la couche sociale et politique supérieure accessible aux premiers groupes. Qualifiant cette islamisation superficielle, Trimingham emploie deux termes très significatifs: “imperial cult” et “cult of the trading and clerical classes”. L'Afrique occidentale a pourtant connu un changement radical lors du jihad peul aux XVIIIe-XIXe siècles. L'islamisation devenue militaire se développa, pourtant, dans son essence, sur la prise d'initiative des groupes cléricaux indigènes-torobé. Le militarisme islamique s'explique plutôt par le prosélytisme puritaniste de ces groupes. La théocratie islamique des Etats peul ainsi apparus annonce l'Ere islamique du “state religion”. Cette théorie typologique de Trimingham, bien qu'acceptable sur le fond, présente certains points discutables. Dans le numéro précédent de ce Journal, M. Takezawa critique, à tort, Trimingham sur sa négligence de l'islamisation commerciale et sur sa méthode “historiste”. Mais au contraire, s'il y a des points discutables, us concernent plutôt sa méthode trop “typologique” ou trop structurale et la négligence, conséquence de sa méthode, à propos du rôle peul dans le jihad peul. Celui-ci doit être considéré dans ses phénomènes totaux. Plus particulièrement, la collaboration ayant exists, bien que plus ou moins antagoniste et tendue, entre les groupes cléricaux dirigeants (torobé ou toronkawa) et les peul éleveurs, leurs rapports dynamiques sont à élucider.
Socio-ecological characters of gorillas in the Kahuzi and the Virunga regions were compared, in relation to environmental factors. A lower population density was estimated for Kahuzi than Virunga. A complex mosaic of primary and secondary montane forests, bamboo forest, and Cyperus swamp in Kahuzi provided a greater variety of gorillas' food items than the relatively simple vegetation of Virunga. Although no difference was detected in the day journey length between both areas, gorillas in Kahuzi tended to range in wider areas, feeding mainly on the leaves or bark of several species of vine, while gorillas in Virunga ranged over small areas feeding on various parts of several herb species. Seasonal food items such as bamboo shoots or fruits stimulated gorillas to shift their ranges between primary and secondary vegetation in Kahuzi. These conditions were possibly responsible for the different frequency of inter-unit encounters between the Kahuzi (low) and Virunga (high) gorillas. Ranging of the Kahuzi gorillas might be affected by the amount and distribution of food resources, while ranging of the Virunga gorillas tended to be affected by social factors at inter-unit encounters. Social structure and its maintenance mode based on female transfer between social units and on male emigration from their natal groups, were almost the same for both areas. There was no difference in group size, age-sex composition per population or per group between the Kahuzi populations and the 1959-60 Virunga population reported by Schaller (1963), but were recognized significant differences between the latter and the 1982 Virunga population. It is suggested that a reduction of National Park size and human disturbance such as cattle raising or poaching might have initiated this social change within the Virunga population in the early 1970's: The reduction of habitat brought the higher density of social units, which increased number of inter-unit encounters in several isolated areas. Inter-unit interactions stimulated male emigration or female transfer to produce lone males or newly-formed groups, and thus decreased group size. Lone males and newly-formed groups increased agonistic interactions between social units, which probably prevented maturing males from participating in violent interactions between prime adult males, and possibly has recently led them to form multi-male groups or all-male groups. Evidence of infanticide observed only in Virunga also implies that competition among male gorillas has recently increased there. These factors suggest the social and behavioral flexibility of gorillas to environmental changes in the montane forest.
After independence in 1961 the institution of agricultural finance in Tanzania were improved based on the idea of Arusha Declaration which stressed on Ujamaa Socialism and reorganized into a new system which aimed to overcome colonial economic strategies which existed. The branches of financial institutions were established mainly in cash crop regions so that more farmers can be lent loans than in the previous period because the government has the perspective which agricultural development is necessary for industrialization. But in spite of the above improvement the agricultural loan has been concentrated to the commercial agriculture and therefore possibility of agricultural development as whole in Tanzania has been blocked. On the other hand, there has been rapid growth of population in Tanzania, where food-production per person has decreased and govermment must import the food. That means the policy of stresseing on commercial crops for industrial development and getting foreign exchange cause a bad circulation: Ignoring subsistence crops cause the food shortages, on the other hand this stagnation of subsistence food crop production affect the condition of the peasants because they have little possibility of receiving agricultural loans. Agricultural loan for peasants is stagnant in the statusquo and they can't extend production. Agriculture in Tanzania must look for the possibility of development under difficult conditions. In that case, the role of agricultural loan institution is important, in future, the policy of loan has to change in order to improve regional differentiation and we hope this system to a better one and stress on subsistence crop production. In addition more long term loans have to be provided than short term loan, by this achievement Tanzania can establish long term economic strategy including industrialization.