First of all i would like to say this is only one of my many theories on the senjus' ability, and for those of you who cannot treat it as such should not comment with flaming.
Well anyway i think that the origin of the sages powerful body is the jubi. I think that before he sealed it within him all he had was the eyes, and after he sealed it within himself its own chakra and power merged with him naturally, also in the manga it is said in the manga after he sealed the beast in he attained immeasurable chakra and power. its kind of like naruto when he learned to control the chakra of kurama he gained an ability similar to hashirama.
i think what made the senju strong was their high chakra levels and their mastery of all forms of shinobi skills, they were called "the clan with a thousand skills". and as for their dna i think they naturally had a huge amount of lifeforce similar to what naruto had when in kyubi mode, basically giving them the ability to use jutsu on the same level as naruto in that mode. and what made hashirama special was his ability to fuse earth and water.
Well anyway i think that the origin of the sages powerful body is the jubi. I think that before he sealed it within him all he had was the eyes, and after he sealed it within himself its own chakra and power merged with him naturally, also in the manga it is said in the manga after he sealed the beast in he attained immeasurable chakra and power. its kind of like naruto when he learned to control the chakra of kurama he gained an ability similar to hashirama.
i think what made the senju strong was their high chakra levels and their mastery of all forms of shinobi skills, they were called "the clan with a thousand skills". and as for their dna i think they naturally had a huge amount of lifeforce similar to what naruto had when in kyubi mode, basically giving them the ability to use jutsu on the same level as naruto in that mode. and what made hashirama special was his ability to fuse earth and water.
