Imagining microtubules as self-created magical prime movers of biology and evolution in general is something I will leave to you. Most rational folks involved realize they are 'simply' an integral feature of extremely complex and interconnected cell machinery, with zero real evidence they ever had any existence preceding or in any way separate from existent cell physiology. The whole is not only far greater than the sum of the parts, it is necessary from the outset. You will furiously disagree. Fine. Just actually leave miocrotubules out of it here. Having flogged that obsession to death elsewhere across many threads. Stick to the actual thread topic.