Why peacock? Why not horse? After all the Arab valued the horse far more than the peacock in their lives.

Therefore the usage of the word peacock must have some other meaning. This Rahi (Author) has spiritual ‘experience’ with birds that has find its counterpart in form of genome ‘data’:

“Relative to other birds (and indeed, all tetrapods), hummingbirds exhibit small and minimally variable genome sizes. This observation is consistent with the hypothesis that the metabolic demands of powered flight, which are extreme in these hovering birds, have played a role in the evolution of reduced genome sizes of birds, probably through the intermediate of cell size.”

Source: “The smallest avian genomes are found in hummingbirds”, T. Ryan Gregory, Proc. R. Soc. B. 

67:19. Didn’t they look ‘Ila (at/towards) the bird(s) above them Sāff-āt and Ya-Qbidh-na, what preserves/maintains/holds them (birds) other than Al-Rahman

أَوَلَمْ يَرَوْا إِلَى الطَّيْرِ فَوْقَهُمْ صَافَّاتٍ وَيَقْبِضْنَ مَا يُمْسِكُهُنَّ إِلَّا الرَّحْمَنُ

Sāff-āt: In the language of the Arab also means to cleanse or purify or remove anything extra or unnecessary, and indeed the genome of the birds have removed all the unnecessary ‘junk’ or ‘repetitive’ DNA in order to become genomically much smaller than most other mammalian or otherwise species. You might want to translate this word into ‘cull’ or ‘culling’.

Ya-Qbidh-na: Which really means to constrict or shrink in size might be translated, properly in this case, into compressed or shrunken. Which after the culling of the DNA in the bird genome, the resultant creature with compressed genome needs much less energy to maintain its living and its motility therefore the high-metabolic flight ranging from the hummingbird to largest migratory birds became possible.

Remark: The non-flying birds have much larger genome than the flying ones e.g. hummingbird genome is 0.91 pg while the ostrich is 2.16 pg. 

The birds were in the darkness of ‘Adam (Non-Being) and the Nur shone upon them and they become Wujud (Being) but they followed the light in a different path than any other creature, and they came close to Allah in a different sort of proximity and that nearness was manifested into our world via two projections:

1. Flight

2. Condensed genome

Therefore something very intimate and special took place between Allah and the flying birds! And what incident was of spiritual nature in the Malakut (Spiritual Realm) the choice of peacock points to this special relationship.