Let us presuppose a universe adjacent to our own, that has collided non-catastrophically with our own on a number of occasions, causing an exchange of matter including humans in the most recent collissions.
Humans have formed a civilisation in this alternate universe, which has bigger, cooler stars, approximately the same goldilocks zones and a slightly higher average temperature on alternate Earth. Humans can survive there, though not as optimally as a natively evolved lifeform.
What might cause the development of a society that emphasises research and development of the life sciences over materials technology, and ultimately result in a transhumanist society as the technology matures?
Collissions between the universes have been occurring since the end of the pre-cambrian era, with increasing frequency and duration. The most recent collissions were around a million years ago, 10,000 years ago, and around 1500 years ago. Humans or pre-humans would have been exchanged each time.
Due to the pre-cambrian collision, there will be life on alternate Earth that is biologically compatible with humans, but will have had billions of years in which to evolve. We may suppose that collissions and exchanges have occurred at around every major time of change in the nature of life on Earth.
I don't need to deemphasise the other sciences, I merely want to emphasise a drive toward genetic transhumanism.
Aside from my stated restrictions, any conditions or societies an answerer deems necessary or unnecessary may be deemed to exist or not as required, provided that their occurrence or failure to occur can be justified.