Markandeyapurana 49.27

49.27

prāyaśaḥ kalpavṛkṣāste saṃbhūtā gṛhasaṃjñitāḥ /
sarve pratyupabhogāśca tāsaṃ tebhyaḥ prajāyate //

As the people died in the course of time, so their prosperity gradually perished everywhere; and when it had altogether perished, men fell down from the sky. Those kalpa trees were commonly produced which are called houses; and they brought forth every kind of enjoyment to those people. At the beginning of the Tretā age the people got their subsistence from those trees. Afterwards in the course of time passionate affection[4] sprung up suddenly among them. By reason of the occurrence of passionate affection menstruation occurred month by month, and conception frequently took place.