Why we have got different types of bodies? Why we haven't got, everyone, the same type of body? Somebody is fat, somebody is very thin, somebody white, somebody black, somebody very beautiful, somebody very ugly. There are so many varieties of bodies. Why? Saṅghāṭa. This is combination, color combination. There are three guṇas. Prakṛteḥ kriyamāṇāni guṇaiḥ karmāṇi sarvaśaḥ (BG 3.27). As you are associating with the guṇas, you are getting different types of body.
That is, Kṛṣṇa is explaining here, that mahā-bhūtāny ahaṅkāra. The ahaṅkāra is very important thing. False ahaṅkāra and real ahaṅkāra. Ahaṅkāra means law of identity. "I am Indian," this is ahaṅkāra. "I am American," this is ahaṅkāra. "I am rich man," this is also ahaṅkāra. "I am poor man." There are so many ahaṅkāras, law of identification. So this ahaṅkāra is the basis of getting a type of body, And... This is the subtle basis, ahaṅkāra. Mano buddhir ahaṅkāra. There are eight material elements: bhūmir āpo 'nalo vāyuḥ khāṁ mano buddhir eva ca (BG 7.4). That is stated in the seventh chapter. This earth, water, fire, air, sky, mind, intelligence, and ahaṅkāra. This is creating my different types of body.