Al-Jakiz’s View on Biological Evolution
After a long study of animals, Al-Jahiz was the first to put forward his view of biological evolution in his Book ofAnimals, which contains the germs of many later evolutionary theories (animal embryology, evolution, adaptation, animal psychology and sociology) "11".
First of all, al-Jahiz’s attempts were made in a truly scientific spirit to classifV animals in a linear series, beginning with the simplest and continuing to the most complex; and at the same time, he arranged them into groups having marked similarities; and these groups were divided into sub-groups to trace the ultimate unit in the species "12"
An early exponent of the zoological and anthropological sciences, al- Jahiz discovered and recognized the effect of environmental factors on animal life; and he also observed the transformation of animal species under different factors. And in many remarkable passages of his book, he also described for us the struggle of existences for survival, its aim and mechanisms and value in a scientific way, as well as in a folkloric way. As to know the mechanistiis of evolution, al-Jahiz described three mechanisms. These are Struggle for Existence, Transformation of species into each other, and Environmental Factors.
Let us now see the mechanisms, as briefly as possible.
Struggle for Existence: al-Jahiz placed the greatest weight on evolution by the struggle for existence, or, in a larger sense, by natural selection. It operates in conjunction with the innate desire for conservation and permanence of the ego. According to al-Jahiz, between every individual existence, there is a natural war for life. The existence are in struggle with each other. Al-Jahiz’s theory of struggle for existence may accordingly be defined as a differential death rate between two variant class of existence, the lesser death rate characterizing the better adapted and stronger class. And for al-Jahiz, the struggle for existence is a divine law; God makes food for some bodies out of some other bodies’ death. He says, “
The rat goes out for collecting his food, and it searches and seizes them. It eats some other inferior animals, like small animals and small birds. . . it hides its babies in disguised underground tunnels for protecting them and himself against the attack of the snakes and of the birds. Snakes like eating rats very much. As for the snakes, they defend themselves from the danger of the beavers and hyenas; which are more powerful than themselves. The hyena can frighten the fox, and the latter frightens all the animals which are inferior to it. ...
this is the law that some existences are the food for others. . . . All small animals eat smaller ones; and all big animals cannot eat bigger ones. Men with each other are like animals. . . God makes cause of some bodies life, “ "13" from some bodies death and vice versa. And according to al-Jahiz, the struggle does not exist only between the members of different species, but also between the members of the same species "14".
From what al-Jahiz has said, we can make an assertion that God has created Nature in a prodigal reproductive character and He has also established a law, which is the biological struggle for existence in order to keep it within a limited ratio. Otherwise, the disorder could appear in Nature and it could lose some of its riches and species. We can see the germs of Darwin’s and the Neo-Darwinian’s theory of Natural Selection in this remarkable passage which we have mentioned above. Transformation of Species: Al-Jahiz, as later Lamarck and Darwin, for example, believes that the transformation of species and mutation is possible. The transformation operates in conjunction with the effect of environmental factors. And he asserted that the original forms branched out into new forms of species by gradually developing new characteristics which helped them to survive environmental conditions. He says, “People said different things about the existence of al-miskh (the original form of quadrupeds) "15". Some accepted its evolution and said that it gave existence to dog, wolf, fox and their similars. The members of this family came from this form (al-miskk).” "16"
And, he adds that God’s will and power is the main causal factor in the transformation, and God can transform any species into another at any time He wants. So al-Jahiz defends the transformation of species and mutation, due to different factors, including God’s will’7, as we have said above. Here al-Jahiz got some of his material from the sayings of different learned men. As for the effect of environmental factors on species, al-Jahiz believes that the food, climate, shelter and other factors have some biological and psychological effects on species. And for him, these factors also lead the species to a hard struggle for survival. In a changed environment, there is also a change in some characters having survival value. The process of changing characters in succeeding generations makes the organisms better adapted to their environment. They thus survive and get a chance to breed and transmit their characteristics to their offspring. So, al-Jahiz based his theory upon the notion of the use and disuse of organs in the adaptation of animals to their environment.
Al-Jahiz says, “Without doubt, we have seen that some Nabatheen navigators resembled the ape in some geographical environment, likely we have also seen some people from Morocco and have found them as like as
al-maskh "
18", except for a little difference.... And it is possible that the polluted air and water, and dust made this change in the character of these Moroccans. . . . If this effect goes on more and more in them, those changes in their bristles, ears, colours, and form (similar to the ape) increase more.... “ "19"
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