Summations Only

Because some speculative ideas lack any evidence.
Otherwise, where should we stop?We could spend the next 100 years teaching someone all the different unevidenced origins of life - 100 different aliens dropping seeds of life; 1000 different gods calling forth life; 10000 different wizards waving their wands.
The number of "what if"s are almost endless.
So, in science, we stick to things we have evidence of. Evidence.
Always evidence. Despite your beliefs, yes - it can be scientific.
Experiments can be done; results can be measured; things can be learned. But some variables are known.
Ultimately, we may never find out the exact way that life originated on Earth, but we can investigate the different ways that life can originate.Edited by Panda, : No reason given.Edited by Panda, : No reason given.

There is no rush. This is not like a chat room - there is no penalty for taking a day or a week to reply.
The main thing that will attract criticism is poorly thought-out responses.So - take your time.
A single good post is worth a dozen one-liners.Edited by Panda, : No reason given.

Shrews are too small for human brains?Then what is preventing larger animals from having a human brain?